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H. A. BERN

A study of the respiration of rat ventral prostate has been carried out with special reference to the effect of added carbohydrate and certain sex steroids.

The average Q o2 value for rat ventral prostate was 9·1. When this tissue was examined 48 hr after castration, there was a significant decrease in the average Q o2 value to 7·1. The rate of respiration remained the same in the absence and in the presence of added glucose or fructose.

A high concentration of testosterone, 50 μg/ml., inhibited the oxygen consumption of ventral prostate; oestradiol had a less pronounced effect. With lower concentrations of testosterone, such as 0·5 μg/ml. or 0·005 μg/ml., variable results were obtained, but the average Q o2 value did not differ significantly from that established for the ventral prostate alone. The addition of testosterone to the ventral prostate from castrate rats did not increase the respiration.

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K. KOHMOTO and H. A. BERN

SUMMARY

Mammotrophic (i.e. mammogenic and/or lactogenic) activity of mouse placentae of different stages (4–19 days of pregnancy) was examined using organ co-culture of placental explants with mammary tissue. The test mammary tissues were taken from midpregnant (11–12 days) nulliparous A/Crgl mice and cultured in a synthetic medium (Waymouth's) supplemented with insulin (5 μg/ml) and aldosterone (1 μg/ml). The responses of mammary gland to placental explants were judged histologically, and were compared with those seen after the addition of ovine prolactin (5 μg/ml). With placentae from 6- to 19-day pregnant animals, distinct mammotrophic activity was seen, with the appearance of eosinophilic secretion in the mammary alveolar lumina, whereas with 4- or 5-day-old 'placentae', no mammotrophic activity was detected. Inasmuch as growth hormone does not substitute for prolactin in mammary gland development and function in the A/Crgl mouse, it can be concluded that a prolactin-like factor is present in the mouse placenta. The influence of placentae on mammary gland was further analysed by transplantation of placental fragments to mammary fat pads. Local lobuloalveolar development was prominent in some instances in the area around the placental transplants.

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D. H. RAMSEY and H. A. BERN

SUMMARY

Ovine prolactin injected subcutaneously for 2 days stimulated an increase in fluid uptake in vitro by everted gut sacs from male Sprague—Dawley rats. Four intestinal segments from each rat were incubated, but only two of the four segments tested showed a prolactin-stimulated increase in fluid transfer in intact rats. In adrenalectomized—nephrectomized rats all four sacs showed an increased fluid transfer after prolactin treatment. Sacs incubated for 1 h in glucose—Ringer solution containing 0·1 mg ovine prolactin/ml did not show an increased water transfer as compared with controls incubated in medium containing albumin. Dietary changes seemed to alter the sensitivity of the gut to prolactin.

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S. S. Madsen and H. A. Bern

ABSTRACT

The effect of ovine GH (oGH) in vivo and recombinant bovine insulin-like growth factor-I (rbIGF-I) in vitro on gill Na+,K+-ATPase activity was investigated in two seasonal experiments conducted during the parr–smolt transformation period of coho salmon.

In 1991, when fish were held under a photoperiod of 12 h light: 12 h darkness, the stimulatory effect of oGH (1 μg/g) on gill Na+,K+-ATPase in vivo decreased at the time of expected parr–smolt transformation. Gill Na+,K+-ATPase from control fish was insensitive to rbIGF-I in vitro from February to June, whereas GH treatment induced sensitivity to rbIGF-I (100–1000 μg/l) in vitro in February and March, but not later in development.

In 1992, when fish were held under natural conditions, oGH (4 μg/g) stimulated gill Na+,K+-ATPase in vivo from February to July. There was, however, a pronounced developmental change in sensitivity of gill Na+,K+-ATPase to rbIGF-I in vitro. In February, gills from control fish were insensitive, but oGH treatment in vivo induced sensitivity to rbIGF-I in vitro (100–1000 μg/l). In April and May, control fish were sensitive to rbIGF-I in vitro. This sensitivity was not further potentiated by oGH treatment in vivo. In June, gills from control or oGH-treated fish were not sensitive to rbIGF-I in vitro, but in July exogenous oGH again induced gill tissue sensitivity to rbIGF-I at 1000 μg/l. Both studies showed that rbIGF-I stimulates gill Na+,K+-ATPase directly; an ability that may depend on priming by endogenous or exogenous GH. This supports the role of IGF-I as an endocrine mediator for GH action during parr–smolt transformation.

Journal of Endocrinology (1993) 138, 23–30

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G. SHYAMALA, T. MORI and H. A. BERN

SUMMARY

Neonatal treatment of female mice with oestrogen or androgen induces persistent vaginal cornification, which may be dependent or independent of ovarian hormones according to the amount administered. The concentration of oestrogen-binding protein in the cytoplasm and in the nuclear fraction was measured in the uterus and vagina of mice treated neonatally with either steroid alone or in combination with prolactin. Vaginal oestrogen responsiveness (dependence) of mice treated with low and high doses of steroids was correlated with oestrogen receptor content. Neonatal treatment with prolactin in combination with the low dosage steroid treatments favoured development of ovary-independent cornification and a concomitant decrease in oestrogen receptors in about 50% of the mice studied.

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D. V. SINGH and H. A. BERN

SUMMARY

Intact female BALB/cCrgl mice, 3–4 weeks old, were pretreated with oestrogen and progesterone for 9 days. Whole mammary glands from these mice were cultivated for 5 days in a synthetic medium supplemented with aldosterone (A), prolactin (MH) and insulin (I), with and without thyroxine (T4) at concentrations ranging from 0·01 to 5 μg./ml.

A medium containing 1 μg. A +5 μg.MH +5 μg.I/ml. was generally optimal for lobulo-alveolar development. Addition of thyroxine to this combination resulted in a decrease in development which was highly significant at higher concentrations. However, when cultures were maintained in media containing suboptimal or low amounts of prolactin (1 μg. A + 3 μg. MH +5 μg. I/ml. and 1 μg. A + 1 μg. MH +5 μg. I/ml., respectively), the results indicate two possible effects of thyroxine: lower amounts of thyroxine had synergistic effects, whereas greater amounts had antagonistic effects on lobulo-alveolar development.

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Y Fukazawa, T Iguchi and H A Bern

Abstract

The anococcygeus muscle (AcM) is one of a pair of thin sheets of smooth muscle inserting on the rectum, having a tendinous origin largely on sacral vertebrae. The cross-sectional area of AcM in the juxtarectal region in 90-day-old male mice was significantly larger than that in females of three strains: BALB/cCrgl, ICR/Jcl and C57BL/Tw. The AcM area in female mice showed strain differences: BALB/c>ICR>C57BL. Five daily injections of testosterone into newborn ICR mice from the day of birth significantly increased the areas of AcM in both sexes at 30 days of age, but five daily injections of oestradiol-17β (OE) decreased them. The AcM area in 60-day-old ICR male mice castrated at 30 days of age was significantly smaller than in intact males, and that in ovariectomized females was significantly larger than in intact females. In both sexes, implantation of a testosterone pellet (12 mg) into gonadectomized mice on the day of gonadectomy stimulated the growth of AcM, and implantation of an OE pellet (12 mg) inhibited the growth of AcM. The AcM in both ICR and C57BL strains showed positive androgen receptor and oestrogen receptor immunostaining at 15 days. Female ICR mice exposed neonatally to diethylstilboestrol (DES) had significantly larger AcM than controls; ovariectomy at 30 days of age did not change the AcM area in 60-day-old DES-exposed mice. However, male mice exposed neonatally to DES had significantly smaller AcM than controls; castration at 30 days of age nullified this inhibition. These results suggest that both androgen and oestrogen play an important role in sexual dimorphism of the mouse AcM. Neonatal exposure to DES (but not to oestradiol) had an irreversible stimulatory effect on the AcM area in female mice.

Journal of Endocrinology (1997) 152, 229–237

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B. A. DONEEN, H. A. BERN and CHOH HAO LI

SUMMARY

These studies are concerned with the structural and functional evolution of the ancestrally related pituitary prolactins and somatotrophins. Prolactin-like biological activities of human somatotrophin (hGH) and its peptide fragments were bioassayed in vitro on the mouse mammary gland and the teleost urinary bladder. Plasmin modified-hGH was as active as hGH in both bioassays. The NH2-terminal 134-residue fragment possessed about 10% of the lactogenic and urinary bladder potency of hGH, whereas the CO2H-terminal 51-residue fragment was inactive at the concentrations observed. These results suggest that the same regions of primary structure are responsible for the prolactin-like actions of hGH on the target organs of lower and higher vertebrates. Alteration of the tertiary structure of hGH, human chorionic somatomammotrophin, and ovine prolactin by performic acid oxidation destroys the mammary gland activities of these hormones.

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C. S. NICOLL, H. A. BERN and DONNA BROWN

SUMMARY

The mammotrophic activities of the hypophysis of two teleostean species (Tilapia mossambica and Carassius auratus auratus), the African lungfish (Protopterus aethiopicus), a salamander (Necturus maculosus), a turtle (Pseudemys scripta elegans) and the domestic pigeon (Columba livia) were compared with those of the hypophysis of three laboratory mammals (rat, hamster and guinea-pig) and purified ovine prolactin. Medium from organ cultures of the pituitaries of these vertebrates was tested for mammotrophic activity by an organ-culture assay system using explants of mammary tissue from mid-pregnant A/Crgl mice. The tetrapod adenohypophyses were as effective in the induction of mammary secretion as the ovine prolactin. In contrast the glands of the lungfish and the two teleosts showed only slight mammotrophic influence. The results indicate that a principle possessing effective mammotrophic activity constitutes part of the 'pituitary apparatus' of all classes of tetrapods. Whether lungfish 'prolactin' is tetrapod-like (highly mammotrophic) or teleostean (minimally effective) in its action must still be considered unresolved, because only immature Protopterus were available.

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J. R. MAINOYA, H. A. BERN and J. W. REGAN

SUMMARY

Mucosal fluid, sodium and chloride transfer were measured in everted sacs of rat, guinea-pig and hamster jejunum, and in rat ileum and colon, and in guinea-pig gall bladder. After treatment of the animal with ovine prolactin, a highly significant enhancement of fluid and NaCl absorption was observed in rat, hamster and guinea-pig jejunum. Prolactin treatment caused a significant increase in fluid and NaCl transfer in rat ileum, but not in guinea-pig ileum or rat colon. Prolactin administration had no consistent effect on fluid and NaCl absorption by the guinea-pig gall bladder. The several regions of the mammalian gut appear to differ in their responsiveness to prolactin.