Search Results

You are looking at 81 - 90 of 1,206 items for :

  • brain development x
  • All content x
Clear All
Restricted access

N. Torres, M. Fanelli, A. L. Alvarez, D. Santajuliana, S. Finkielman, and C. J. Pirola

ABSTRACT

Betamethasone was administered on alternate days to rats, and the role of the central cholinergic system in the development of hypertension assessed. After 15 days of treatment the systolic blood pressure of treated rats was significantly higher than that of control rats. Peripheral administration of atropine but not of methyl atropine reduced systolic pressure in glucocorticoid-treated rats and had no effect in controls. Therefore, [3H]quinuclidinyl benzylate binding, sodium-dependent high-affinity choline uptake and choline acetyltransferase studies were performed in the septal area, anteroventrolateral medulla (AVLM), anterior hypothalamic preoptic area (AH/PO) and hypothalamus. The density of muscarinic receptors was increased in the hypothalamus and AVLM of treated rats without significant changes in affinity. Choline acetyltransferase activity significantly decreased in the AVLM and increased in the AH/PO. In addition, a decrease in the hypothalamus and an increase in the AH/PO of sodium-dependent high-affinity choline uptake was observed in glucocorticoid-treated rats. These results suggest the presence of an enhanced muscarinic cholinergic activity in several brain nuclei in rats with glucocorticoid-induced hypertension. This activation could be due to pre- and post-synaptic hypersensitivity.

Journal of Endocrinology (1991) 129, 269–274

Restricted access

S. D. Holman and J. B. Hutchison

ABSTRACT

The effects of testosterone propionate (TP) on brain mechanisms involved in the sexual differentiation of ultrasonic vocalizations were examined in Mongolian gerbils (Meriones unguiculatus). Treatment of neonatal females with TP fully masculinized the rate of emission of the upsweep precopulatory ultrasound during adult sexual interactions with oestrous females. Intracranial implantation of small crystals of TP mixed with cholesterol (65 ng) into females 1–15 h after birth also masculinized the upsweep vocalization emitted in adulthood. Implants of TP positioned in the hypothalamic area had a significantly greater masculinizing effect than TP implants outside this region, or pure cholesterol implants. Two other sexually dimorphic vocalizations, the modulated (mainly precopulatory) and unmodulated (mainly copulatory) calls were masculinized by systemic TP, but intracranial TP had no significant masculinizing action on these calls. Genital structures of females which received neonatal injections of TP were strongly virilized in that their clitorides were lengthened and male-type cornified spines were present on the glans. Females which had received intracranial implants of TP were not virilized peripherally in adulthood. We conclude that testosterone or its metabolites have a direct hypothalamic effect on the development of masculine upsweep vocalizations. Because the other vocalizations were insensitive to intracranial TP, the underlying neural tissues may have different thresholds of response to androgen.

J. Endocr. (1985) 107, 355–363

Free access

C Clapp, FJ Lopez-Gomez, G Nava, A Corbacho, L Torner, Y Macotela, Z Duenas, A Ochoa, G Noris, E Acosta, E Garay, and G Martinez de la Escalera

Formation of new capillary blood vessels, termed angiogenesis, is essential for the growth and development of tissues and underlies a variety of diseases including tumor growth. Members of the prolactin hormonal family bind to endothelial cell receptors and have direct effects on cell proliferation, migration and tube formation. Because many angiogenic and antiangiogenic factors are produced by endothelial cells, we investigated whether endothelial cells expressed the prolactin gene. Here we show that bovine brain capillary endothelial cells (BBCEC) in culture express the full-length prolactin messenger RNA, in addition to a novel prolactin transcript, lacking the third exon of the gene. In addition cultures of BBCEC synthesize and secrete prolactin-like immunoreactive proteins with apparent molecular masses of 23, 21 and 14 kDa. The prolactin-like nature of these proteins in supported by the observation that Nb2-cells, a prolactin-responsive cell line, were stimulated to proliferate when co-cultured with endothelial cells and this stimulation was neutralized with prolactin-directed antibodies. Finally, consistent with a possible autocrine effect of endothelial-derived prolactins, polyclonal and monoclonal prolactin antibodies specifically inhibited basal and basis fibroblast growth-factor-stimulated growth of endothelial cells. Taken together, the present findings support the hypothesis of the prolactin gene being expressed in endothelial cells as proteins that could act in an autocrine fashion to regulate cell proliferation.

Restricted access

P. SÖDERSTEN

Male rats were treated daily with 100 μg of the anti-oestrogen ethamoxytriphetol (MER-25) or oil during the first 10 days of life and tested for lordosis behaviour and mounting behaviour as intact adults, after castration and after castration and oestradiol benzoate or testosterone propionate treatment. The MER-25-treated rats showed higher levels of lordosis behaviour than oil-treated rats in all four treatment groups. Under each of these endocrine conditions, except after castration alone, the MER-25-treated rats showed a reduced capacity to ejaculate. Treatment of the neonatal rat with MER-25 reduced body weight in adulthood but did not change the weight of the accessory sexual glands, the testes, the number of cornified papillae on the glans penis or plasma testosterone concentrations during development. The response of the accessory sexual glands and cornified papillae on the glans penis to treatment with oestradiol benzoate or testosterone propionate after castration in adulthood was unaffected by treatment with MER-25. It is suggested that formation of oestrogen in the neonatal male rat brain from testosterone in the circulation inhibits the capacity to show lordosis behaviour and facilitates the capacity to ejaculate in response to gonadal hormone treatment in adulthood.

Free access

M Tena-Sempere, J Navarro, L Pinilla, LC Gonzalez, I Huhtaniemi, and E Aguilar

The biological actions of estrogens on target cells are mediated by two nuclear receptors: the estrogen receptor (ER) alpha and the recently characterized ER beta. In the male rat, the physiological role of estrogens involves multiple actions, from masculinization of brain areas related to reproductive function and sexual behavior to regulation of testicular development and function. Paradoxically, however, administration of high doses of estrogen during the critical period of neonatal differentiation results in an array of defects in the reproductive axis that permanently disrupt male fertility. The focus of this study was to characterize the effects and mechanism(s) of action of neonatal estrogenization on the pattern of testicular ER alpha and beta gene expression during postnatal development. To this end, groups of male rats were treated at day 1 of age with estradiol benzoate (500 microg/rat), and testicular ER alpha and ER beta mRNA levels were assayed by semi-quantitative RT-PCR from the neonatal period until puberty (days 1-45 of age). Furthermore, the expression of androgen receptor (AR) mRNA was evaluated, given the partially overlapping pattern of tissue distribution of ER alpha, ER beta and AR messages in the developing rat testis. In addition, potential mechanisms for neonatal estrogen action were explored. Thus, to discriminate between direct effects and indirect actions through estrogen-induced suppression of serum gonadotropins, the effects of neonatal estrogenization were compared with those induced by blockade of gonadotropin secretion with a potent LHRH antagonist in the neonatal period. Our results indicate that neonatal exposure to estrogen differentially alters testicular expression of alpha and beta ER messages: ER alpha mRNA levels, as well as those of AR, were significantly decreased, whereas relative and total expression levels of ER beta mRNA increased during postnatal/prepubertal development after neonatal estrogen exposure, a phenomenon that was not mimicked by LHRH antagonist treatment. It is concluded that the effect of estrogen on the expression levels of ER alpha and beta mRNAs probably involves a direct action on the developing testis, and cannot be attributed to estrogen-induced suppression of gonadotropin secretion during the neonatal period.

Restricted access

M J Pesek and M A Sheridan

Abstract

Somatostatins are a diverse family of peptides that influence various aspects of animal growth, development, and metabolism. Recent work in our laboratory has shown that somatostatins stimulate hepatic lipolysis in rainbow trout. In this study we characterized somatostatin-binding sites in trout hepatic membrane preparations. We also examined changes in binding characteristics brought about by food deprivation. Binding of [Tyr11]-somatostatin-14 (SS-14) was saturable, reversible, and time- and temperature-dependent. Under optimal conditions, [Tyr11]-SS-14 specific binding averaged 5·7 ± 0·3%. While SS-14 and SS-28 (an N-terminally extended form of SS-14 and derived from the same gene as SS-14) displaced [Tyr11]-SS-14 specific binding (ED50 values of approximately 50 nm and 100 nm respectively), salmon SS-25 (containing [Tyr7,Gly10]-SS-14 at its C terminus and presumably derived from a gene different from that giving rise to SS-14/SS-28), except at pharmacological concentrations, did not. Significant specific binding was also detected in brain, esophagus, stomach, upper and lower intestine, pancreas, and adipose tissue. Scatchard analysis suggested the existence of two classes of hepatic somatostatin-binding sites: a high-affinity site with a K d of 23 nm and Bmax of 1·4 pmol/mg protein and a low-affinity site with a K d of 379 nm and Bmax of 4·9 pmol/mg protein. Fasting resulted in reduced growth and elevated plasma levels of SS-14 compared with fed animals. SS-14 binding capacity of the high-affinity class in liver membranes isolated from fasted fish increased by 120% over that from fed counter-parts. No difference in K d for the high-affinity binding class or in either K d or Bmax of the low-affinity class was noted between fasted and fed animals. These data support the role of the liver as a target of somatostatin and suggest that fasting enhances hepatic sensitivity to SS-14 binding.

Journal of Endocrinology (1996) 150, 179–186

Restricted access

P. Licht, B. T. Pickering, H. Papkoff, A. Pearson, and A. Bona-Gallo

ABSTRACT

A glycoprotein of neurohypophysial origin was found to have cofractionated with FSH prepared from pituitary glands of the green turtle, Chelonia mydas. Antiserum raised against this preparation contained high antibody titres and affinity for the neurohypophysial component and allowed development of a specific radioimmunoassay to monitor its purification and distribution in the brain. Immunocytochemistry revealed that the glycoprotein was concentrated in the pars nervosa and associated nerve tracts passing through the median eminence to the supraoptic and paraventricular nuclei; similar distributions were observed in turtles and rats. The antiserum to the turtle material bound radiolabelled rat vasopressin (VP)-neurophysin and precipitated precursors of this neurophysin, but it did not cross-react with rat oxytocin-neurophysin. An amino-terminal alanine was also consistent with the structure of rat VP-neurophysin, but the turtle molecule was larger than the corresponding rat molecule. Limited tryptic digests of the turtle glycoprotein contained two components, one of which bound to lysine VP.

Both components contained carbohydrate, but only the one which bound to VP cross-reacted in a radioimmunoassay for rat VP-neurophysin. The apparent surge in plasma immuno-FSH at the time of oviposition previously described in the turtle probably represented release of a neurophysin-like 'carrier' molecule associated with secretion of the neurohypophysial hormone (e.g. arginine vasotocin; AVT) responsible for oviduct contractility. These data suggest that the neurohypophysial glycoprotein represents a partially processed AVT precursor and provide the first biochemical evidence of a mammalian-like biosynthetic pathway for neurohypophysial hormones in a non-mammalian species.

J. Endocr. (1984) 103, 97–106

Restricted access

M Kaouass, P Deloyer, and G Dandrifosse

Abstract

In this study we investigated whether brain-gut peptides are implicated in the activation of the hypophysial-adrenal axis (HAA) in suckling rats treated orally with spermine.

The first group of rats received i.p. injections of bombesin, vasoactive intestinal polypeptide (VIP), somatostatin or neurotensin, starting on day 11 of life, and killed on day 14. The small intestine was removed and analysed for its content of proteins, DNA, polyamines and for its specific activity (SA) of disaccharidases. The second group of rats received one of the hormones cited above and was killed 45 min after the treatment for determination of corticosterone plasma concentration. Rats of the third group were adrenalectomised then treated with bombesin as the first group. The fourth group of rats was orally treated with spermine and sacrificed 2, 3, 4, 6 and 8 h thereafter for analysis of plasma and intestinal concentrations of bombesin.

The i.p. injection of bombesin increased the sucrase and maltase SA in the whole small intestine, while it decreased the lactase SA in the distal part. Intestinal weight and length, contents of DNA, protein, spermidine and spermine, and corticosterone plasma levels were enhanced by bombesin treatment. Somatostatin, neurotensin and VIP were ineffective on all the parameters studied. Adrenalectomy, in bombesin-treated rats, decreased the sucrase and maltase SA in the whole intestine, and decreased the lactase SA in the proximal intestine. It had no effect on intestinal weight and length, and protein content. Oral administration of spermine had no effect on plasma concentration of bombesin, whereas it decreased the content of this peptide in the whole small intestine.

It is possible that bombesin may control intestinal development in suckling rats and be a link between the ingestion of spermine and the liberation of corticosterone by the adrenal glands.

Journal of Endocrinology (1997) 153, 429–436

Free access

SK Peirce, WY Chen, and WY Chen

Human prolactin (hPRL) has been reported to be involved in breast and prostate cancer development. The hPRL receptor (hPRLR) is expressed in a wide variety of tissues in at least three isoforms. In this study, a one-step real time reverse transcription PCR technique was used to determine relative expression levels of hPRLR mRNA in eleven human breast cancer cell lines, HeLa cells, three prostate cancer cell lines and nine normal human tissues. The housekeeping gene beta-actin was used for internal normalization. We demonstrate that hPRLR mRNA is up-regulated in six of the eleven breast cancer cell lines tested when compared with normal breast tissue. Of the cancer cell lines tested, we found that T-47D cells have the highest level of hPRLR mRNA, followed by MDA-MB-134, BT-483, BT-474, MCF-7 and MDA-MB-453 cells. In two breast cancer cell lines (MDA-MB-468 and BT-549), the hPRLR levels were found to be comparable to that of normal breast tissue. Three breast cancer cell lines (MDA-MB-436, MDA-MB-157 and MDA-MB-231) expressed hPRLR mRNA at levels lower than that of normal tissue. In contrast, in all three commonly used prostate cancer cell lines (LNCaP, PC-3 and DU 145), the levels of hPRLR mRNA were found to be down-regulated relative to that of normal prostate tissue. Of nine normal human tissues tested, we found that the uterus and the breast have the highest levels of hPRLR mRNA, followed by the kidney, the liver, the prostate and the ovary. The levels of hPRLR mRNA were the lowest among the trachea, the brain and the lung.

Free access

Hiranya Pintana, Wanpitak Pongkan, Wasana Pratchayasakul, Nipon Chattipakorn, and Siriporn C Chattipakorn

cognitive function in the testosterone-deprived rats. Discussion The major findings of the present study are as follows: i) the condition of obesity in testosterone-deprived rats leads to the development of peripheral insulin resistance, impairment of brain