Sexual dimorphism in insulin sensitivity and susceptibility to develop diabetes in rats

in Journal of Endocrinology

The goal of this study was to evaluate gender-related differences of some metabolic determinants of insulin sensitivity and of susceptibility to the effects of diabetes. Changes in body weight, blood glucose, and serum insulin concentrations were compared between female and male Wistar rats in prepubertal, pubertal, and adult stages of life. A diabetic model was induced by streptozotocin (STZ) under nicotinamide protection in both sexes and metabolic patterns were evaluated during the next 4 weeks. Finally, the pancreases were processed for morphometric analysis. In the three age groups, at similar blood glucose levels, higher fasting serum insulin levels were found in female as compared with age matched male rats. After STZ treatment, female rats show lower insulin and higher glucose levels, and a worse survival rate as compared with male rats. The more severe disease phenotype observed in female animals is associated with a more dramatic perturbation of pancreatic islet morphology. Significant differences exist in insulin sensitivity between sexes, females being less sensitive to insulin than males at all age groups and more susceptible to the rapid development of a more severe form of diabetes than males.

Abstract

The goal of this study was to evaluate gender-related differences of some metabolic determinants of insulin sensitivity and of susceptibility to the effects of diabetes. Changes in body weight, blood glucose, and serum insulin concentrations were compared between female and male Wistar rats in prepubertal, pubertal, and adult stages of life. A diabetic model was induced by streptozotocin (STZ) under nicotinamide protection in both sexes and metabolic patterns were evaluated during the next 4 weeks. Finally, the pancreases were processed for morphometric analysis. In the three age groups, at similar blood glucose levels, higher fasting serum insulin levels were found in female as compared with age matched male rats. After STZ treatment, female rats show lower insulin and higher glucose levels, and a worse survival rate as compared with male rats. The more severe disease phenotype observed in female animals is associated with a more dramatic perturbation of pancreatic islet morphology. Significant differences exist in insulin sensitivity between sexes, females being less sensitive to insulin than males at all age groups and more susceptible to the rapid development of a more severe form of diabetes than males.

Introduction

Diabetes mellitus is a common metabolic disease. Type 2 diabetes is rapidly becoming pandemic, and although the origin of this disease is not entirely clear, it is accepted that insulin resistance is important in its pathogenesis and that defects in insulin secretion by pancreatic β-cells lead to hyperglycemia and the onset of diabetes (King et al. 1998, Wild et al. 2004). It is interesting that the proportion of diabetes is higher in women than in men (King et al. 1998). Recent studies in young populations show that 5-year-old girls and female adolescents show higher insulin resistance than boys (Hoffman et al. 2000, Murphy et al. 2004). It has been proposed that sex-related genes could be important in explaining this difference (Murphy et al. 2004).

Different rodent models also show differences in insulin sensitivity and secretion between genders. For example, glucose-induced insulin secretion by isolated pancreatic islets from female Wistar rats at 4, 8, and 21 days of age is twofold higher than the respective secretion in males (Lopes Da Costa et al. 2004). Also, the spontaneous incidence of type 1 diabetes in the non-obese diabetic mice is 85% in females and 25% in males (Hawkins et al. 1993, Winer et al. 2002).

In this study, we analyzed differences between sexes in blood glucose concentration and serum insulin levels at different ages in Wistar rats. We also measured differences between both sexes in some metabolic and morphologic parameters in a diabetic rat model induced with streptozotocin (STZ) and nicotinamide (Masiello et al. 1998).

Materials and Methods

Materials

Reagents were obtained from the following sources: STZ, nicotinamide, mouse anti-rat glucagon, Triton X-100, propidium iodide, sodium citrate, and salts from Sigma-Aldrich; rat insulin ELISA (ALPCO Diagnostics, Windham, NH, USA); Paraplast (Sherwood Medical Co., St Louis, MO, USA); insulin-antiserum (ICN, Irvine, CA, USA), fluorescein isothiocyanate (FITC)-conjugated goat anti-guinea pig IgG, CY5-conjugated goat anti-mouse IgG (Jackson Immunoresearch Laboratories, West Grove, PA, USA).

Animals

Groups of 12 prepubertal (21 days), 12 pubertal (45 days), and 12 adult (2 months) female and male Wistar rats were obtained from the local animal facility, housed separated by sex, maintained in a 14 h light (0600–2000):10 h darkness cycle, and allowed free access to standard laboratory rat diet and distilled water. Animals were handled according to the National Institutes of Health Guide for the Care and Use of Laboratory Animals (NIH No. 85-23, revised 1985). All methods used in this study were approved by the Internal Council and the Animal Care Committee of The Institute of Cellular Physiology, Universidad Nacional Autonoma de Mexico (UNAM).

Insulin sensitivity

Insulin sensitivity was assessed using fasting insulin and glucose, as described by McAuley et al. (2001). These parameters have been validated as an appropriated single laboratory measure to describe insulin sensitivity in individuals (Laakso 1993, McAuley et al. 2001).

Insulin tolerance test

Rats were injected intraperitoneally with insulin (1 U/kg body weight) and glucose was measured in the tail vein 0, 15, 30, and 60 min after injection, using an automatic glucometer (Precision, QIDTM, MediSense, Inc., Abbott Laboratories Company). This test was always performed at 1100–1400 h (Goren et al. 2004).

Glucose tolerance test

Rats were fasted overnight (16 h) and injected intraperitoneally with glucose (2 mg/kg); 0, 15, 30, 60, and 120 min after injection, glucose was measured in tail vein blood with a glucometer (Goren et al. 2004).

Assessment of abdominal fat

Prepubertal female and male Wistar rats were killed by sodium pentobarbital (60 mg/kg) overdose. In male rats, epididymal fat pads were removed and weighed, whereas in female rats, parametrial and retroperitoneal fat pads were removed and weighed together.

Diabetic model

Three independent groups of ten young adult male and female rats received a single i.p. dose (87.5 mg/kg) of nicotinamide dissolved in saline solution. After 15 min, β-cell destruction was induced by a single i.p. dose (90 mg/kg) of STZ, dissolved in citrate buffer (pH 4.5) immediately before use. In parallel, a control group of animals received vehicles of both substances. A pilot group of five male and five female adult rats received a single nicotinamide i.p. dose (175 mg/kg), dissolved in saline solution. After 15 min, β-cell destruction was induced as described above. Also parallel controls received vehicles.

Blood extraction and glucose and insulin measurements

For the next 4 weeks, we measured once a week, in the morning, body weight, blood glucose, and serum insulin concentrations. Rats were previously fasted for 4 h (from 0700 to 1100 h) and anesthetized with ether before blood extraction by intraorbital retrobulbar plexus puncture. Sera were obtained and stored at −20 °C until assayed.

Blood glucose concentrations were determined as described above. Only nicotinamide- and STZ-treated rats with blood glucose concentrations above 16 mmol/l were included in the study.

To determine the insulin concentration in the sera samples, we used an ultra sensitive rat insulin ELISA as instructed by the fabricant. The absorbance of the enzymatic reaction was measured at 450 nm in an ELISA reader (Bio Rad). All determinations were performed in duplicate. Assay sensitivity by this method was 10 pg/ml and the total interassay coefficient of variation was 3.2%.

Morphometric analysis

After 4 weeks, animals were anesthetized with sodium pentobarbital (40 mg/kg) and the pancreases were removed for morphometric and immunohistochemical analysis. Finally, animals were killed by cervical dislocation.

The pancreases from six control and six diabetic rats of each sex were removed, fixed overnight in 4% paraformaldehyde in PBS, dehydrated, and embedded in Paraplast. Four serial sections 5 μm thick were selected, each 100 μm from each tail pancreas, and mounted on slides. Paraffin sections were deparaffinized, rehydrated, permeabilised, and subsequently incubated overnight with guinea pig anti-porcine insulin antibody (1:4000) as recommended by the technical bulletins suppliers. Then, sections were incubated with a second FITC-conjugated goat anti-guinea pig IgG antibody for insulin detection (1:100), then incubated for 4 h with mouse anti-rat glucagon (1:6000) and a second CY5-conjugated goat anti-mouse IgG (1:100). Sections were counterstained with propidium iodide at 10 μg/ml to facilitate nuclear identification.

Sections were observed by confocal microscopy using a Bio Rad MRC-1024 system, equipped with a Kr/Ar laser attached to an inverted Nikon Diaphot TMD 300 microscope, with an oil-immersion 40× objective (Nikon Corporation, Tokyo, Japan). Iris aperture, gain, and laser power remained fixed in each session, FITC was excited with a 494 nm wavelength, and emitted light was band-passed with a 520 nm filter, while CY5 was excited with a 650 nm wavelength, and emitted light was band-passed with a 670 nm filter. Confocal images were viewed and processed using Confocal Assistant 4.02 (Todd Clark University of Minnesota, MN, USA).

The following controls were performed to achieve a reliable double immunostaining. (1) Negative control of antibodies: experimental protocols were carried out without the addition of primary or secondary antibody. (2) Antisera specificity controls were performed by overnight preadsorbing anti-insulin and anti-glucagon antibodies with their respective antigens, followed by the same protocol. No fluorescent signal could be detected in either control (not shown).

The percentages of β- and α-cell areas in the pancreas were calculated by dividing insulin-positive or glucagon-positive areas in one section by the total area of this section and multiplying this ratio by 100. As described above, only islets containing 15 or more endocrine cells were measured (Xu et al. 1999).

Morphometric measurements were performed using a manual optical picture image analyzer; Laser Pix program Bio Rad version 4.0.0.13 on a projected image of the histological sections of the pancreas. Nearly 140 islets per rat were analyzed.

Statistical analysis

All data are presented as the mean±s.e.m.; n denotes the number of the evaluated subjects. Statistical significance was assessed by one-way ANOVA followed by Fisher’s multiple range tests and P-values less than 0.01 were considered statistically significant (Stat view 4.57.0.0, Abacus Concepts Inc., Berkeley, CA, USA).

Results

Metabolic development

Body weight, blood glucose, and serum insulin were measured and compared between female and male, pre-pubertal (21 days), pubertal (45 days), and adult (2 months) rats (Table 1).

As described above, pubertal and adult males were nearly 20% heavier than females (Engelbregt et al. 2000). In contrast, we found no difference in body weight in prepubertal rats between sexes. However, interestingly, the percentage of abdominal fat at this developmental stage was significantly higher in females (4.3±0.07%) than in males (2.09±0.3%).

Fasting blood glucose values were similar between sexes at all stages. However, glucose concentration in prepubertal animals was 20% higher (Table 1) and insulin concentration was lower, when compared with pubertal and adult rats.

At the three developmental stages studied, fasting insulin concentration in females was 45% higher compared with males (Table 1).

Glucose tolerance test

This test was performed in animals that had fasted for 16 h (Fig. 1A and C) and reflects insulin-stimulated glucose clearance and inhibition of glucose release by the liver (Goren et al. 2004). We did not observe differences between the sexes in glucose values. As described above, compared to pubertal rats, prepubertal rats showed higher glucose concentrations.

Insulin sensitivity test

We evaluated insulin sensitivity with an insulin tolerance test (Fig. 1B and D). A pharmacological dose of insulin was injected to non-fasted rats. At 15 min, a similar decrease in plasmatic glucose was observed in both sexes. However, at 30 and 60 min after injection, male glucose concentrations were 20% lower, compared to females. These observations suggest that prepubertal female rats are less sensitive to insulin than males (Fig. 1B). A similar response was observed in pubertal female rats (Fig. 1D).

Diabetic model

To further explore sex differences in insulin sensitivity, we developed an experimental diabetic model using STZ (95 mg/kg) and nicotinamide (87.5 mg/kg; see Methods), and compared the metabolic patterns between sexes during 4 weeks of diabetes development.

Previously, the same amount of STZ combined with a higher concentration of nicotinamide (175 mg/kg) was used in a pilot group. In this experiment, no changes were observed in body weight in experimental animals, compared to controls (not shown). Only one female and male developed hyperglycemia before week 5 and all the animals survived more than 8 weeks. In order to have less protection to STZ toxic effect, we decided to use a lower nicotinamide dose (87.5 mg/kg).

In diabetes loss of body weight and hyperglycemia are observed

While body weight in control males increased throughout the experiment, it did not significantly change in control females. In contrast, diabetic males did not gained weight and a 13% mean reduction was observed in diabetic females (Fig. 2A).

All the experimental animals developed hyperglycemia. However, female glucose values were higher than male values. As shown in Fig. 2B, this increase was significantly progressive throughout the experiment.

Serum insulin concentration and animal survival decreased in diabetic rats

Figure 2C compares serum insulin concentration in control and diabetic animals. Clearly, diabetic animals secreted less insulin than their respective controls, the major decrease, of nearly 80%, being observed in females.

Interestingly, while 88% of diabetic males survived the first week of treatment, only 63% of the females remained alive. This tendency prevailed throughout the experiment (Fig. 2D).

Changes in pancreatic β-cells mass

After 4 weeks of treatment, we compared pancreatic islet morphology and insulin and glucagon distribution in control and diabetic animals. Figure 3A and B shows that control islets from both sexes are rounded and composed of nearly 80% β-cells, located predominantly in the core of the islets. Most of the α-cells were surrounding β-cells and represented nearly 10% of the cells in the islets.

We observed many differences between pancreatic tissue obtained from female and male controls that can be summarized as follows: (a) mean islets area in females was 40% higher than in males (Fig. 3A). (b) Areas occupied by β- and α-cells in pancreas of females were nearly 22 and 50% higher respectively when compared with males (Fig. 3B and C). (c) Islet size and number in females was nearly 20% higher than males (Table 2).

Pancreatic islets in diabetic animals of both sexes were scarce, elongated and disorganized, as shown in Fig. 4C and D. In the islets that were not destroyed by the treatment, α-cells were located in the core, filling up the space previously occupied by β-cells (Fig. 4 and Table 2).

Discussion

We observed sexual dimorphism in insulin sensitivity, function and morphology of prepubertal, pubertal, and adult rat pancreatic islets, and susceptibility to develop diabetes. To our knowledge, this is the first report showing that serum insulin levels are higher in normal prepubertal, pubertal, and adult females than in age-matched males.

Further, we observed that females have more and bigger islets than males. However, both sexes showed similar fasting blood glucose concentrations. Moreover, plasmatic glucose response to an insulin challenge, which directly reflects insulin sensitivity of peripheral tissue, was lower in females than in males (Fig. 1).

Lower insulin sensitivity in females could be partially explained by the presence of higher fat proportions in females than in males (Schwartz & Porte 2005). In relation to their weight, we observed more abdominal fat in female prepubertal rats than in males. Other authors previously reported that this difference is present throughout life (Clegg et al. 2003). Abdominal and visceral adiposity has been linked to insulin resistance and metabolic syndrome. Adipocytes from this region produce more cytokines and show differences in metabolic activity compared with fat of other regions (Giorgino et al. 2005).

Prepubertal girls are more resistant to insulin than boys (Hoffman et al. 2000). Girls under 5 years show higher insulin levels, but similar blood glucose concentrations, than boys (Murphy et al. 2004). The ‘EarlyBird Study’ (Wilkin et al. 2004) shows that insulin resistance is inherited from mothers not from fathers and this agrees with the ‘DECODE Study Group’ (2003), which suggests that females are intrinsically more insulin resistant than males throughout life. Also in non-primate animal models, it had been observed that maternal obesity induced impaired glucose tolerance only in female offspring (Han et al. 2005).

Adipose tissue is an endocrine organ that secretes hormones such as leptin and adiponectin (Kershaw & Flier 2004). Leptin levels can be high in obesity due to insulin and leptin resistance by their different targets (Lazar 2005). Interestingly, leptin production and secretion is higher in female rats than in matched males (Pinilla et al. 1999, Engelbregt et al. 2000, Smith & Waddell 2003) and after STZ treatment, serum leptin levels decrease (Havel et al. 1998, 2000). This can be explained because there is a loss of weight and fat in diabetic animals.

On the other hand, estrogens and testosterone modulate pancreatic hormone secretion (Faure et al. 1988, Nadal et al. 1998, Sutter-Dub 2002, Morimoto et al. 2005). It has been reported that estrogens increase electrical activity and modulate insulin secretion (Nadal et al. 1998) and also decrease glucagon secretion by preventing low glucose-induced [Ca]i oscillations in α-cells (Ropero et al. 2002). In addition, variations in serum insulin level and insulin mRNA in pancreas during the estrous cycle has been observed, suggesting that sexual steroid hormones modulate insulin secretion (Morimoto et al. 2001).

We observed that diabetes development in response to STZ treatment under nicotinamide protection is more severe in female rats than in males, because females developed the disease faster.

Diabetic males did not gain weight as did their matched-controls and a progressive disproportion in this parameter was observed during the experiment. Interestingly, when animals of both sexes began losing weight the risk of dying increased and females presented lower survival rates compared with males and with female controls (FCs).

Moreover, females showed more damaged β-cells and fewer, smaller pancreatic islets and accordingly, higher hyperglycemia and less serum insulin concentration than males.

In order to compare responses to males and females, we did the same experiments in castrated rats (unpublished results). One week after the treatment, castrated animals showed higher levels of hyperglycemia (26±0.7 mmol/l) than diabetic males (20±2 mmol/l) and females (21±1 mmol/l). This observation is in accordance with previous results where we found that testosterone protects rat pancreatic β-cells against STZ-induced apoptosis (Morimoto et al. 2005).

Despite showing similar blood glucose concentration between sexes at all ages and in all the conditions studied, after 5 and 16 h of fasting and in fed animals, healthy females have more and bigger pancreatic islets, and higher serum insulin concentrations. The following factors could be implicated in the sexual dimorphism in insulin sensitivity: (1) insulin secretion is higher in females than in males at all ages studied. Since insulin stimulates glucose uptake and metabolism in adipose tissue, the greater fat-to-lean mass ratio seen in females of all ages, as previously observed, may be significant. (2) As shown in other studies, genetic background and (3) sex steroids might influence insulin biosynthesis or/and action, as well as β-cell survival. More studies are needed to entirely answer these questions.

After 4 weeks of diabetes, females show less and smaller pancreatic islets, and less serum insulin concentration than both FCs and diabetic males, and consequently, diabetic females have higher blood glucose values and lower survival rate than male diabetic rats, indicating a more severe response to the same treatment.

These results contribute to our understanding of the sexual differences in glucose homeostasis and may contribute to the future development of new and better therapeutic strategies for treating diabetes mellitus.

Table 1

Metabolic status of development in female and male rats

PrepubertalPubertalAdult
MaleFemaleMaleFemaleMaleFemale
Data represent mean±s.e.m. for at least 12 rats in each condition. *P<0.01 with respect to male age matched; †with respect to pubertal and adult.
Body weight (g)82±4†87±5†253±7209±4*303±3278±5*
Blood glucose (G) (mmol/l)9±0.03†9±0.02†7±0.037±0.027±0.027±0.03
Serum insulin (I) (pmol/l)14±3†47±16*†110±9160±12*104±10151±9*
I/G ratio (pmol/mmol)1.6±1†5.2±1*†14.7±122.2±1*14.5±120.2±1*
Table 2

Morphometric measurement of pancreatic islets in control and diabetic female and male rats

Control maleControl femaleDiabetic maleDiabetic female
Data represent mean the ±s.e.m. for at least six rats in each condition. *P<0.01 with respect to male control; †P<0.01 with respect to female control.
Islet size (μm2)14 180±132017 156±1311*9174±1224*8073±1055†
Islets in pancreas (each 10 mm2)4.78±0.616.40±0.06*3.10±0.77*2.75±0.52†
Figure 1
Figure 1

Glucose homeostasis in rats at 21 (A, B) and 45 (C, D) days of age. Open circles represent males and closed circles, females. After 16 h of fasting animals were subjected to glucose tolerance test (A, C) and insulin tolerance test (B, D), as described in Materials and Methods. Data represent mean±s.e.m. of at least six rats in each group. *P<0.01 vs male.

Citation: Journal of Endocrinology 190, 2; 10.1677/joe.1.06596

Figure 2
Figure 2

Body weight (A), blood glucose (B), serum insulin (C) and survival (D) was monitored weekly in control and diabetic rats. Data represent the mean±s.e.m. of at least ten rats in each experimental condition. Male control (MC; •), male diabetic (MD; ○), female control (FC; ▪), and female diabetic (FD; □). *P<0.01 vs MC; †P<0.01 vs FC, ‡P<0.01 vs MD.

Citation: Journal of Endocrinology 190, 2; 10.1677/joe.1.06596

Figure 3
Figure 3

Representative histological sections of islets of female (A) and male (B) control rats and islets of female (C) and male (D) diabetic rats, incubated with anti-insulin (green) and anti-glucagon (blue) antibodies conjugated with a fluorescent dye, and counterstained with propidium iodide (red). Scale bar 50 μm.

Citation: Journal of Endocrinology 190, 2; 10.1677/joe.1.06596

Figure 4
Figure 4

Endocrine area in pancreas of male control (MC), female control (FC), male diabetic (MD) and female diabetic (FD) rats. Data represent means±s.e.m. *P<0.01 vs MC; †P<0.01 vs female control.

Citation: Journal of Endocrinology 190, 2; 10.1677/joe.1.06596

We thank Hector Malagon for help with animal care; also to Angelica Zepeda and Alvaro Caso for proofreading and discussion of the manuscript. This study was supported by the following grants: IN211800 and IN203903 from Dirección General de Asuntos del Personal Académico (DGAPA), Universidad Nacional Autónoma de México (UNAM), and D39822-Q from Consejo Nacional de Ciencia y Tecnología (CONACyT). P Vital and M E Larrieta were recipients of a Scholarship grant from CONACYT and DGEP. The authors declare that there is no conflict of interest that would prejudice the impartiality of this scientific work.

References

  • CleggDJ Riedy CA Smith KA Benoit SC & Woods SC 2003 Differential sensitivity to central leptin and insulin in male and female rats. Diabetes52682–687.

    • Search Google Scholar
    • Export Citation
  • DECODE Study Group 2003 Age- and sex-specific prevalences of diabetes and impaired glucose regulation in 13 European cohorts. Diabetes Care2661–69.

    • Search Google Scholar
    • Export Citation
  • EngelbregtMJ Houdijk ME Popp-Snijders C & Delemarre-van de Waal HA 2000 The effects of intra-uterine growth retardation and postnatal undernutrition on onset of puberty in male and female rats. Pediatric Research48803–807.

    • Search Google Scholar
    • Export Citation
  • FaureA Haouari M & Sutter BC 1988 Short term and direct influence of oestradiol on glucagon secretion stimulated by arginine. Diabetes and Metabolism14452–454.

    • Search Google Scholar
    • Export Citation
  • GiorginoF Laviola L & Eriksson JW 2005 Regional differences of insulin action in adipose tissue: insights from in vivo and in vitro studies. Acta Physiologica Scandinavica18313–30.

    • Search Google Scholar
    • Export Citation
  • GorenHJ Kulkarni RN & Kahn CR 2004 Glucose homeostasis and tissue transcript content of insulin signaling intermediates in four inbred strains of mice: C57BL/6 C57BLKS/6 DBA/2 and 129X1. Endocrinology1453307–3323.

    • Search Google Scholar
    • Export Citation
  • HanJ Xu J Epstein PN & Liu YQ 2005 Long-term effect of maternal obesity on pancreatic beta cells of offspring: reduced beta cell adaptation to high glucose and high-fat diet challenges in adult female mouse offspring. Diabetologia481810–1818.

    • Search Google Scholar
    • Export Citation
  • HavelPJ Uri-Hare JY Liu T Stanhope KL Stern JS Keen CL & Ahren B 1998 Marked and rapid decreases of circulating leptin in streptozotocin rats: reversal by insulin. American Journal of Physiology274R1482–R1491.

    • Search Google Scholar
    • Export Citation
  • HavelPJ Hahn TM Sindelar DK Baskin DG Dallman MF Weigle DS & Schwartz MW 2000 Effects of streptozotocin-induced diabetes and insulin treatment on the hypothalamic melanocortin system and muscle uncoupling protein 3 expression in rats. Diabetes49244–252.

    • Search Google Scholar
    • Export Citation
  • HawkinsT Gala RR & Dunbar JC 1993 The effect of neonatal sex hormone manipulation on the incidence of diabetes in nonobese diabetic mice. Proceedings of the Society for Experimental Biology and Medicine202201–205.

    • Search Google Scholar
    • Export Citation
  • HoffmanRP Vicini P Sivitz WI & Cobelli C 2000 Pubertal adolescent male-female differences in insulin sensitivity and glucose effectiveness determined by the compartment minimal model. Pediatric Research48384–388.

    • Search Google Scholar
    • Export Citation
  • KershawEE & Flier JS 2004 Adipose tissue as an endocrine organ. Journal of Clinical Endocrinology and Metabolism892548–2556.

  • KingH Aubert RE & Herman WH 1998 Global burden of diabetes 1995–2025: prevalence numerical estimates and projections. Diabetes Care211414–1431.

    • Search Google Scholar
    • Export Citation
  • LaaksoM1993 How good a marker is insulin level for insulin resistance? American Journal of Epidemiology137959–965.

  • LazarMA2005 How obesity causes diabetes: not a tall tale. Science307373–375.

  • Lopes Da CostaC Sampaio De Freitas M & Sanchez Moura A 2004 Insulin secretion and GLUT-2 expression in undernourished neonate rats. Journal of Nutritional Biochemistry15236–241.

    • Search Google Scholar
    • Export Citation
  • McAuleyKA Williams SM Mann JI Walker RJ Lewis-Barned NJ Temple LA & Duncan AW 2001 Diagnosing insulin resistance in the general population. Diabetes Care24460–464.

    • Search Google Scholar
    • Export Citation
  • MasielloP Broca C Gross R Roye M Manteghetti M Hillaire-Buys D Novelli M & Ribes G 1998 Experimental NIDDM: development of a new model in adult rats administered streptozotocin and nicotinamide. Diabetes47224–229.

    • Search Google Scholar
    • Export Citation
  • MorimotoS Cerbón MA Alvarez-Alvarez A Romero-Navarro G & Díaz-Sánchez V 2001 Insulin gene expression pattern in rat pancreas during the estrous cycle. Life Sciences682979–2985.

    • Search Google Scholar
    • Export Citation
  • MorimotoS Mendoza-Rodríguez CA Hiriart M Larrieta ME Vital P & Cerbón MA 2005 Protective effect of testosterone. Journal of Endocrinology187217–224.

    • Search Google Scholar
    • Export Citation
  • MurphyMJ Metcalf BS Voss LD Jeffery AN Kirkby J Mallam KM & Wilkin TJ 2004 Girls at five are intrinsically more insulin resistant than boys: the Programming Hypotheses Revisited. The EarlyBird Study (EarlyBird 6). Pediatrics11382–86.

    • Search Google Scholar
    • Export Citation
  • NadalA Rovira JM Laribi O Leon-quinto T Andreu E Ripoll C & Soria B 1998 Rapid insulinotropic effect of 17beta-estradiol via a plasma membrane receptor. FASEB Journal121341–1348.

    • Search Google Scholar
    • Export Citation
  • PinillaL Seoane LM Gonzalez L Carro E Aguilar E Casanueva FF & Dieguez C 1999 Regulation of serum leptin levels by gonadal function in rats. European Journal of Endocrinology140468–473.

    • Search Google Scholar
    • Export Citation
  • RoperoAB Soria B & Nadal A 2002 A nonclassical estrogen membrane receptor triggers rapid differential actions in the endocrine pancreas. Molecular Endocrinology16497–505.

    • Search Google Scholar
    • Export Citation
  • SchwartzMW & Porte D Jr 2005 Diabetes obesity and the brain. Science307375–379.

  • SmithJT & Waddell BJ 2003 Developmental changes in plasma leptin and hypothalamic leptin receptor expression in the rat: peripubertal changes and the emergence of sex differences. Journal of Endocrinology176313–319.

    • Search Google Scholar
    • Export Citation
  • Sutter-DubMT2002 Rapid non-genomic and genomic responses to progestogens estrogens and glucocorticoids in the endocrine pancreatic B cell the adipocyte and other cell types. Steroids6777–93.

    • Search Google Scholar
    • Export Citation
  • WildS Roglic G Green A Sicree R & King H 2004 Global prevalence of diabetes: estimates for the year and projections for 2030. Diabetes Care271047–1053.

    • Search Google Scholar
    • Export Citation
  • WilkinTJ Voss LD Metcalf BS Mallam K Jeffery AN Alba S & Murphy MJ 2004 Metabolic risk in early childhood: the EarlyBird Study. International Journal of Obesity and Related Metabolic Disorders28S64–S69.

    • Search Google Scholar
    • Export Citation
  • WinerS Astsaturov I Gaedigk R Hammond-McKibben D Pilon M Song A Karges W Arpaia E McKerlie C Zucker P Singh B & Dosch HM 2002 ICA69null Nonobese diabetic mice develop diabetes but resist disease acceleration by cyclophosphamide. Journal of Immunology168475–482.

    • Search Google Scholar
    • Export Citation
  • XuG Stoffers DA Habener JF & Bonner-Weir S 1999 Exendin-4 stimulates both beta-cell replication and neogenesis resulting in increased beta-cell mass and improved glucose tolerance in diabetic rats. Diabetes482270–2276.

    • Search Google Scholar
    • Export Citation

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  • View in gallery

    Glucose homeostasis in rats at 21 (A, B) and 45 (C, D) days of age. Open circles represent males and closed circles, females. After 16 h of fasting animals were subjected to glucose tolerance test (A, C) and insulin tolerance test (B, D), as described in Materials and Methods. Data represent mean±s.e.m. of at least six rats in each group. *P<0.01 vs male.

  • View in gallery

    Body weight (A), blood glucose (B), serum insulin (C) and survival (D) was monitored weekly in control and diabetic rats. Data represent the mean±s.e.m. of at least ten rats in each experimental condition. Male control (MC; •), male diabetic (MD; ○), female control (FC; ▪), and female diabetic (FD; □). *P<0.01 vs MC; †P<0.01 vs FC, ‡P<0.01 vs MD.

  • View in gallery

    Representative histological sections of islets of female (A) and male (B) control rats and islets of female (C) and male (D) diabetic rats, incubated with anti-insulin (green) and anti-glucagon (blue) antibodies conjugated with a fluorescent dye, and counterstained with propidium iodide (red). Scale bar 50 μm.

  • View in gallery

    Endocrine area in pancreas of male control (MC), female control (FC), male diabetic (MD) and female diabetic (FD) rats. Data represent means±s.e.m. *P<0.01 vs MC; †P<0.01 vs female control.

References

  • CleggDJ Riedy CA Smith KA Benoit SC & Woods SC 2003 Differential sensitivity to central leptin and insulin in male and female rats. Diabetes52682–687.

    • Search Google Scholar
    • Export Citation
  • DECODE Study Group 2003 Age- and sex-specific prevalences of diabetes and impaired glucose regulation in 13 European cohorts. Diabetes Care2661–69.

    • Search Google Scholar
    • Export Citation
  • EngelbregtMJ Houdijk ME Popp-Snijders C & Delemarre-van de Waal HA 2000 The effects of intra-uterine growth retardation and postnatal undernutrition on onset of puberty in male and female rats. Pediatric Research48803–807.

    • Search Google Scholar
    • Export Citation
  • FaureA Haouari M & Sutter BC 1988 Short term and direct influence of oestradiol on glucagon secretion stimulated by arginine. Diabetes and Metabolism14452–454.

    • Search Google Scholar
    • Export Citation
  • GiorginoF Laviola L & Eriksson JW 2005 Regional differences of insulin action in adipose tissue: insights from in vivo and in vitro studies. Acta Physiologica Scandinavica18313–30.

    • Search Google Scholar
    • Export Citation
  • GorenHJ Kulkarni RN & Kahn CR 2004 Glucose homeostasis and tissue transcript content of insulin signaling intermediates in four inbred strains of mice: C57BL/6 C57BLKS/6 DBA/2 and 129X1. Endocrinology1453307–3323.

    • Search Google Scholar
    • Export Citation
  • HanJ Xu J Epstein PN & Liu YQ 2005 Long-term effect of maternal obesity on pancreatic beta cells of offspring: reduced beta cell adaptation to high glucose and high-fat diet challenges in adult female mouse offspring. Diabetologia481810–1818.

    • Search Google Scholar
    • Export Citation
  • HavelPJ Uri-Hare JY Liu T Stanhope KL Stern JS Keen CL & Ahren B 1998 Marked and rapid decreases of circulating leptin in streptozotocin rats: reversal by insulin. American Journal of Physiology274R1482–R1491.

    • Search Google Scholar
    • Export Citation
  • HavelPJ Hahn TM Sindelar DK Baskin DG Dallman MF Weigle DS & Schwartz MW 2000 Effects of streptozotocin-induced diabetes and insulin treatment on the hypothalamic melanocortin system and muscle uncoupling protein 3 expression in rats. Diabetes49244–252.

    • Search Google Scholar
    • Export Citation
  • HawkinsT Gala RR & Dunbar JC 1993 The effect of neonatal sex hormone manipulation on the incidence of diabetes in nonobese diabetic mice. Proceedings of the Society for Experimental Biology and Medicine202201–205.

    • Search Google Scholar
    • Export Citation
  • HoffmanRP Vicini P Sivitz WI & Cobelli C 2000 Pubertal adolescent male-female differences in insulin sensitivity and glucose effectiveness determined by the compartment minimal model. Pediatric Research48384–388.

    • Search Google Scholar
    • Export Citation
  • KershawEE & Flier JS 2004 Adipose tissue as an endocrine organ. Journal of Clinical Endocrinology and Metabolism892548–2556.

  • KingH Aubert RE & Herman WH 1998 Global burden of diabetes 1995–2025: prevalence numerical estimates and projections. Diabetes Care211414–1431.

    • Search Google Scholar
    • Export Citation
  • LaaksoM1993 How good a marker is insulin level for insulin resistance? American Journal of Epidemiology137959–965.

  • LazarMA2005 How obesity causes diabetes: not a tall tale. Science307373–375.

  • Lopes Da CostaC Sampaio De Freitas M & Sanchez Moura A 2004 Insulin secretion and GLUT-2 expression in undernourished neonate rats. Journal of Nutritional Biochemistry15236–241.

    • Search Google Scholar
    • Export Citation
  • McAuleyKA Williams SM Mann JI Walker RJ Lewis-Barned NJ Temple LA & Duncan AW 2001 Diagnosing insulin resistance in the general population. Diabetes Care24460–464.

    • Search Google Scholar
    • Export Citation
  • MasielloP Broca C Gross R Roye M Manteghetti M Hillaire-Buys D Novelli M & Ribes G 1998 Experimental NIDDM: development of a new model in adult rats administered streptozotocin and nicotinamide. Diabetes47224–229.

    • Search Google Scholar
    • Export Citation
  • MorimotoS Cerbón MA Alvarez-Alvarez A Romero-Navarro G & Díaz-Sánchez V 2001 Insulin gene expression pattern in rat pancreas during the estrous cycle. Life Sciences682979–2985.

    • Search Google Scholar
    • Export Citation
  • MorimotoS Mendoza-Rodríguez CA Hiriart M Larrieta ME Vital P & Cerbón MA 2005 Protective effect of testosterone. Journal of Endocrinology187217–224.

    • Search Google Scholar
    • Export Citation
  • MurphyMJ Metcalf BS Voss LD Jeffery AN Kirkby J Mallam KM & Wilkin TJ 2004 Girls at five are intrinsically more insulin resistant than boys: the Programming Hypotheses Revisited. The EarlyBird Study (EarlyBird 6). Pediatrics11382–86.

    • Search Google Scholar
    • Export Citation
  • NadalA Rovira JM Laribi O Leon-quinto T Andreu E Ripoll C & Soria B 1998 Rapid insulinotropic effect of 17beta-estradiol via a plasma membrane receptor. FASEB Journal121341–1348.

    • Search Google Scholar
    • Export Citation
  • PinillaL Seoane LM Gonzalez L Carro E Aguilar E Casanueva FF & Dieguez C 1999 Regulation of serum leptin levels by gonadal function in rats. European Journal of Endocrinology140468–473.

    • Search Google Scholar
    • Export Citation
  • RoperoAB Soria B & Nadal A 2002 A nonclassical estrogen membrane receptor triggers rapid differential actions in the endocrine pancreas. Molecular Endocrinology16497–505.

    • Search Google Scholar
    • Export Citation
  • SchwartzMW & Porte D Jr 2005 Diabetes obesity and the brain. Science307375–379.

  • SmithJT & Waddell BJ 2003 Developmental changes in plasma leptin and hypothalamic leptin receptor expression in the rat: peripubertal changes and the emergence of sex differences. Journal of Endocrinology176313–319.

    • Search Google Scholar
    • Export Citation
  • Sutter-DubMT2002 Rapid non-genomic and genomic responses to progestogens estrogens and glucocorticoids in the endocrine pancreatic B cell the adipocyte and other cell types. Steroids6777–93.

    • Search Google Scholar
    • Export Citation
  • WildS Roglic G Green A Sicree R & King H 2004 Global prevalence of diabetes: estimates for the year and projections for 2030. Diabetes Care271047–1053.

    • Search Google Scholar
    • Export Citation
  • WilkinTJ Voss LD Metcalf BS Mallam K Jeffery AN Alba S & Murphy MJ 2004 Metabolic risk in early childhood: the EarlyBird Study. International Journal of Obesity and Related Metabolic Disorders28S64–S69.

    • Search Google Scholar
    • Export Citation
  • WinerS Astsaturov I Gaedigk R Hammond-McKibben D Pilon M Song A Karges W Arpaia E McKerlie C Zucker P Singh B & Dosch HM 2002 ICA69null Nonobese diabetic mice develop diabetes but resist disease acceleration by cyclophosphamide. Journal of Immunology168475–482.

    • Search Google Scholar
    • Export Citation
  • XuG Stoffers DA Habener JF & Bonner-Weir S 1999 Exendin-4 stimulates both beta-cell replication and neogenesis resulting in increased beta-cell mass and improved glucose tolerance in diabetic rats. Diabetes482270–2276.

    • Search Google Scholar
    • Export Citation

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