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Biomedical subjects

B D Goldman

Publications and source records attributed to B D Goldman.

At least 127 records · Page 7Linked to original sources
PubMed1977

Developmental changes in serum luteinizing hormone, follicle stimulating hormone and androgen levels in males of two inbred mouse strains.

A comprehensive developmental study of serum LH, FSH and androgen concentrations was carried out in male mice of two inbred strains. Gonadotropic hormone (GTH) levels rose 10-15 days prior to the pubertal increase in serum androgen with FSH preceding LH in this regard. In both strains GTH titer rose to a peak at 30 or 35 days and then steadily declined to adult levels which were strain-specific. Serum androgen was detected at low, relatively steady levels until the pubertal increase between 30 and 50 days postpartum. The results are interpreted as supporting the hypothesis that a shift in feedback sensitivity, occurring at about 20 days of age, may be involved in the onset of puberty in the male mouse.

Age Factors↗
PubMed1977

Effect of melatonin administered during the night on reproductive function in the Syrian hamster.

Syrian hamsters were maintained on a long photoperiod (lights on 0600-2000 h) and injected daily with melatonin (10 microgram per injection) for 6-7 weeks. Females injected at 2000 h or 0400 h ceased estrous cyclicity, and males treated similarly at these times had reduced testis weights by the sixth week of treatment. Daily administration of the same dosage of melatonin at 2400 and 0100 h failed to interrupt estrous cyclicity or reduce testis weight. These observations suggest that exogenous melatonin administered at 2000 h or 0400 h may be temporally adding to endogenous circulating melatonin, inducing gonadal quiescence.

Animals↗
PubMed1976

Suckling and LH-induced progesterone secretion in lactating hamsters (Mesocricetus auratus).

The effects of suckling and LH upon serum progesterone levels in lactating hamsters were investigated. Diurnal rhythms in serum levels of progesterone and LH occur throughout lactation in the hamster and these levels are normally higher between 15.00 and 17.00 than between 8.00 and 12.00 (lights on 6.00-20.00). Hamsters injected with 10 mug of LH at 8.00 on day 9 of lactation had higher levels of serum progesterone 2 h after injections than did vehicle-injected controls. Suckling was also found to induce an increase in serum progesterone concentrations. 30 min of suckling from 10.30 to 11.00 on days 10 or 11 of lactation resulted in increased serum levels of progesterone and prolactin, but had no measurable effect upon serum LH levels in animals bled at 11.00. However, suckling for 30 min from 15.00 to 15.30 had no effect upon serum progesterone levels, although it did result in increased titers of both serum LH and prolactin at 15.30. Ovariectomy on day 7 of lactation resulted in lowered levels of serum progesterone at 11.00 on day 11 of lactation and abolished the suckling-induced increase in serum progesterone concentrations. These findings suggest that in the lactating hamster (1) suckling bouts stimulate progesterone secretion from the ovaries, and (2) the diurnal rise in serum progesterone levels is stimulated in part by the increase in serum levels of LH.

Animals↗
PubMed1976

Regulation of serum gonadotropins by photoperiod and testicular hormone in the Syrian hamster.

Male hamsters were maintained on long (14L:10D) or short (10L:14D) photoperiods. The serum concentrations of LH and FSH were reduced in the animals kept on the short photoperiod, and these animals had atrophied testes and sex accessories. Serum gonadotropin concentrations increased following castration in both long and short photoperiods, but gonadotropin secretion was inhibited by much smaller doses of testosterone in the males maintained on the short photoperiod as compared to males kept on a long photoperiod. The levels of testosterone required to suppress serum gonadotropin levels in castrated animals corresponded reasonably well with the serum androgen levels observed in intact males, suggesting that serum androgen is a major regulator of gonadotropin secretion in the male hamster.

Androgens↗
PubMed1976

Effect of melatonin on the reproductive systems of male and female Syrian hamsters: a diurnal rhythm in sensitivity to melatonin.

Hamsters were maintained on a long photoperiod (14L:10D) and were injected once daily with melatonin (10-25 mug) or sesame oil. Males which received melatonin during the afternoon (e.g., 6.5-13.75 h after lights-on) showed regressed testes and decreased levels of serum LH and FSH after several weeks of treatment. Injections of the oil vehicle or injections of melatonin given in the morning (3 h after lights-on) had no detectable effect on testicular size or on serum gonadotropins. Females which received melatonin during the afternoon became acyclic after several weeks of treatment and showed a diurnal pattern of LH secretion. The acyclic females required 4-6 weeks to resume estrous cyclicity following termination of the melatonin injections. The effects of melatonin on gonadal function and on serum gonadotropin concentrations in both sexes were similar to the previously observed effects of prolonged exposure to short photoperiods. These results indicate that chronic daily injections of melatonin can depress reproductive function in hamsters and that the effectiveness of the injections is dependent upon the time of day at which they are administered.

Animals↗
PubMed1975

Influence of neonatal castration or neonatal anti-gonadotropin treatment on fertility, phallus development, and male sexual behavior in the mouse.

Male mice were castrated on the day of birth or were treated with anti-gonadotropin serum (AGS) successively on days 1, 3, and 5 of age. When the adult AGS-treated males were compared with normal rabbit serum (NRS)-treated males with respect to fertility, male sexual behavior, gonadotropin release, body size, and penis size it was found that: (1) fertility of AGS-treated males did not differ from that of NRS-treated males; (2) AGS-treated males showed a significant reduction in penis size, compared with NRS-treated males; (3) both groups showed high levels of male sexual behavior; (4) neither group showed the capacity to support ovulation in ovarian grafts from immature mice. It was also observed that the fertility of female mice treated with AGS on days 1, 3, and 5 of age did not differ from that of control females treated with comparable doses of NRS. Male mice castrated at birth showed a significant reduction in male sexual behavior and penis size compared with males first sham-operated at birth then castrated at 25 days of age. Thus, males castrated at birth were similar to males receiving AGS in infancy, except for sex behavior. The results suggest that the neonatal pituitary in the mouse may not have an important role in the process of sexual differentiation. Previous data for the male rat were compared with those for the mouse.

Animals↗
PubMed1975

Serum gonadotropins and follicular development in the Syrian hamster.

Hamster serum gonadotropins were measured by RIA at 4 h intervals during the estrous cycle. On the afternoon of proestrus both LH and FSH exhibited a surge, but unlike the situation in the rat and mouse FSH returned to "baseline" with LH by early evening of proestrus. Shortly following this return FSH concentrations increased and reached a second peak by noon on estrus which was equal in magnitude and longer in duration than that occurring on proestrus. FSH fell to its lowest levels on diestrus 2 (D2) and early proestrus. Serum gonadotropins were measured by RIA 6 h following unilateral ovariectomy on D2. A slight elevation of LH resulted while FSH increased to a level equal in magnitude to that found during the proestrous surge. In intact females administration of a total of 45 mug FSH in 5 injections on D2 resulted in ovulation of twice the normal number of eggs. The t1/2 of this rat FSH in the male hamster was found to be 122 minutes. The low levels of FSH during the cycle between D2 and proestrus, the large increase in serum FSH following unilateral ovariectomy, and the "doubled" ovulation in intact hamsters following the administration of FSH on D2, suggest that the serum FSH concentration on D2 is critical in determining the number of follicles which will be available for the subsequent ovulation.

Animals↗
PubMed1975

Ovarian control of prolactin secretion during late pregnancy in the rat.

The involvement of the ovaries during late pregnancy in the rat upon serum prolactin was investigated. Ovariectomy on day 17 or day 21 of pregnancy prevented the dramatic rise of prolactin found in sham-ovariectomized animals between days 21 and 23 of pregnancy. While animals ovariectomized on day 17 of pregnancy failed to carry viable fetuses beyond day 19 of pregnancy, rats ovariectomized on day 21 of pregnancy had viable pups in utero on day 23 of pregnancy. These data suggest that the rise in serum prolactin during late pregnancy is stimulated by ovarian factors.

Animals↗
PubMed1975

The relationship between the rat of testosterone infusion and gonadotropin secretion.

Prepubertal and young adult male rats were castrated and continuous intravenous infusions of testosterone were administered for 2-3 days. Blood samples were obtained at various intervals and serum concentrations of FSH and LH were determined. In 43-day-old males a dose of approximately 57 mug/day was required to suppress serum LH to levels observed in intact controls, and FSH was also suppressed at this dose. Within one day after termination of infusions serum LH and FSH concentration had returned to (or exceeded) the levels observed in castrates infused with vehicle only. This was true even after a very large dose of testosterone had been administered (918 mug/day). In 59-day-old males serum LH was suppressed somewhat by 40 mug testosterone/day and further by 200 mug/day. FSH did not appear to be suppressed as readily in these rats as compared to the younger animals. Further experiments in which castrated rats were injected with testosterone or testosterone propionate revealed marked differences in the magnitude and time course of the action of these compounds upon LH release. It is suggested that the rate of metabolism of these steroids is important in limiting their effects, especially when administered by single daily injections. Furthermore, it appears that "recovery" of the hypothalamic-pituitary system from exposure to high concentrations of testosterone is rapid following clearance of the steroid from the blood.

Age Factors↗