Albert S. Berkowitz

Inhibition of Dunning Tumor Growth by Melatonin

Injections of the pineal hormone melatonin reduced growth and increased doubling time of the R3327H Dunning prostatic adenocarcinoma in the Copenhagen X Fisher rat. This occurred even though testosterone levels (50% of normal) were ostensibly high enough to maintain normal tumor growth. Melatonin may act directly upon the conversion of testosterone to dihydrotestosterone to inhibit tumor growth. Alternatively, a more complicated mechanism may be involved since studies on MCF breast cancer tissue indicate an estrogen requirement for inhibition of growth by melatonin.

Preliminary experince with a combination of clomiphene and variable dosages of menopausal gonadotropins for enhanced follicular recruitment

A combination of clomiphene citrate and human menopausal gonadotropin was employed for enhanced follicular recruitment in an in vitro fertilization program. All patients received 50 mg of clomiphene and 1 ampule of human menopausal gonadotropin daily from cycle day 5 through cycle day 9. Follicular monitoring was begun on day 10 using a combination of ultrasound measurement of follicular size and number and determination of peripheral estradiol levels. Based on the size and number of follicles, the peirpheral levels of estradiol, and the rate of follicular growth and increase in estradiol, human menopausal gonadotropin was continued at a dosage of 1 to 3 ampules/day through the day of human chorionic gonadotropin administration. Human chorionic gonadotropin was administered on the evening of the day the largest follicle reached or exceeded 20 mm in mean diameter if the estradiol levels had been rapidly rising or reaching a plateau and had exceeded a minimal level of 300 pg/ml. Using this protocol, 30 of 33 patients underwent laparoscopy, 29 patients had successful oocyte recovery, and 23 patients underwent embryo replacement, with the establishment of six clinical pregnancies.

Effect of melatonin in vivo upon FSH and LH release from hamster pituitary glands.

The effect of chronic daily afternoon injections of melatonin upon basal and melatonin-modulated release of FSH and LH was investigated in superfused hamster anterior pituitary glands. The basal release rate of both FSH and LH began to decline following the beginning of melatonin injections, and reached a nadir after six weeks. Basal release rate of FSH and LH then began to spontaneously increase and reached a plateau at 13 weeks of injections. The inhibition by melatonin upon FSH and LH release in vitro gradually declined during the period of melatonin injections. After six weeks of melatonin injections the release rate of FSH was no longer suppressed by melatonin superfusion, while the release rate of LH became refractory to melatonin suppression in vitro after nine weeks of melatonin injections. These results demonstrate a change in the release rates of both basal and melatonin-inhibited gonadotropin release during melatonin-induced testicular regression and recrudescence in hamsters.

Fetal alcohol exposure and adult tumorigenesis

Adult rats exposed to prenatal alcohol were evaluated for their susceptibility to either hormone- or chemical-inducing tumors. In the first study, rats exposed to prenatal alcohol displayed an increased propensity to beta-estradiol (E2)-induced adenohypophyseal prolactinoma. The susceptibility was manifest as a potentiated increase in anterior pituitary weight as well as in serum prolactin levels after 1 and 3 weeks but not 5 weeks of hormone treatment. Two weeks after withdrawing the E2-implant, the prolactinoma underwent involution and serum prolactin reversed to baseline levels. The high concentrations of serum corticosterone were also reduced but did not return to baseline levels after E2 removal. In the second study, nitrosomethylbenzylamine (NMBA) was utilized to induce esophageal cancer in adult rats. There were no significant differences in tumor incidence or size between the prenatal alcohol-exposed and the pair-fed cohorts. However, the NMBA-treated prenatal alcohol-exposed rats displayed a marked decrease in thymus: body wt ratio as well as adrenal gland hyperplasia. The results suggest that no single mechanism can account for the variable susceptibility displayed by the prenatal alcohol-exposed rats to chemical carcinogens. Some of the observed changes, however, may be attributable to the long-lasting adverse effects of prenatal alcohol exposure on the well-being of the adult host.

Endogenous luteinizing hormone surges following administration of human chorionic gonadotropin: further evidence for lack of loop feedback in humans.

The existence of inhibitory short- and ultrashort-loop feedback mechanisms for luteinizing hormone (LH), while documented in animals, has been questioned in humans. Since human chorionic gonadotropin (hCG) binds to LH receptors but can be distinguished from LH in immunoassays, it is possible to identify LH surges in the face of exogenously administered hCG. The present study demonstrates LH surges at midcycle in normal volunteers and in women undergoing controlled ovarian hyperstimulation, given hCG. This provides further evidence for lack of loop feedback control of LH secretion in humans.

Melatonin's differential inhibition of FSH and LH release from hamster pituitary glands

Melatonin initially inhibited FSH secretion from superfused adult male hamster anterior pituitary glands obtained at 8:30 a.m. However, there was a gradual rebound during melatonin superfusion followed by an overshoot above baseline when melatonin was discontinued (morning response). Melatonin continuously inhibited FSH secretion during superfusion of hamster anterior pituitary glands obtained at 3:30 p.m., with a rebound evident only when melatonin was withdrawn (afternoon response). Melatonin continuously inhibited LH secretion from these superfused pituitaries, with a return to baseline levels only upon melatonin withdrawal. Prior pinealectomy or constant light could reverse the FSH morning response to an afternoon response, and late-morning melatonin injections could reverse the FSH afternoon response to a morning response. Neither prior pinealectomy, constant light nor melatonin injections affected melatonin inhibition of LH secretion from superfused pituitary glands. These results suggest that melatonin differentially inhibits FSH and LH secretion from isolated superfused hamster anterior pituitary glands.

Differences in the cyclic nucleotide mediation of luteinizing hormone-releasing hormone action on the rat and hamster anterior pituitary gland

A continuous flow superfusion system which was previously developed in our laboratory was utilized to study the modulation of LH and FSH release by cyclic nucleotides and LHRH from anterior pituitary glands (APG) obtained from rats or hamsters. There was a transient increase in LH and FSH secretion from superfused rat APG in response to superfusion with 1 X 10(-3) M 1-methyl-3-isobutyl-xanthine (MIX), while 1 X 10(-4) MIX M had no effect. Furthermore, a dose of 5 X 10(-5) M MIX did not potentiate the gonadotrophin-releasing effect of 1 X 10(-10) M LHRH. Neither 1 X 10(-3) M 8-Br-cAMP nor 1 X 10(-3) M 8-Br-cGMP mimicked the gonadotrophin-releasing effects of 1 X 10(-9) M LHRH. In the experiments utilizing hamster APG, FSH release gradually increased during superfusion with 1 X 10(-3) M MIX or 1 X 10(-4) M MIX, while LH release was transient but significantly increased in response to superfusion with both doses of MIX. A dose of 5 X 10(-5) M MIX potentiated the effect of a low dose of LHRH (1 X 10(-10) M) upon both LH and FSH secretion. 1 X 10(-3) M 8-Br-cAMP mimicked the effect of LHRH upon LH and FSH released from superfused hamster APG, while 1 X 10(-3) M 8-Br-cGMP was inhibitory. These results suggest that cyclic nucleotides are involved in the mediation of the LHRH-induced release of gonadotropins from the anterior pituitary gland of the hamster, but do not mediate the LHRH-induced release of gonadotropins from the rat anterior pituitary gland.

Undetected ovulation in in vitro fertilization-embryo transfer patients.

A retrospective evaluation was done of 102 consecutive in in vitro fertilization-embryo transfer (IVF-ET) treatment cycles that culminated in surgical intervention for oocyte pickup. In 35% of these patients, a disparity was noted in the number of mature follicles present on the day of human chorionic gonadotropin administration, compared with the day of surgery. This suggests the occurrence of undetected ovulation. An endogenous luteinizing hormone (LH) surge was detected in 14 of these patients. Another cohort showed evidence of early luteinization without a detected endogenous LH surge. Finally, a group without early luteinization was defined. Possible explanations for these outcomes and the implications for success of IVF-ET are discussed.

Influence of the pineal gland on the reproductive system of the male house mouse.

Procedures designed to express pineal-mediated antigonadotropic activity were performed upon male house mice. Neither blinding nor blinding plus olfactory bulbectomy of house mice resulted in testicular involution within 12 weeks. The pineal gland appears to be of little significance to reproduction in the house mouse.

Minimal quantities of FSHβ subunit are released by rat anterior pituitary cells in primary culture

FSH beta in the medium and extracts of cultured rat anterior pituitary cells was quantitated with a heterologous radioimmunoassay utilizing anti-rFSH beta and hFSH beta as the standard and tracer. After 4 days in culture, extracts were prepared from washed cells, cells incubated for 6 h or 24 h in fresh medium or cells incubated for 6 h in the presence of 10(-7) M GnRH. FSH beta/rFSH molar ratios were approximately 0.05, 0.04, 0.21 and 0.35, respectively. The elevation in FSH beta/rFSH molar ratios in 24 h basal and GnRH-treated cultures was due in part to an increase in intracellular FSH beta. Both unstimulated and GnRH-treated cultures contained non-detectable quantities of FSH beta in the medium (less than 0.063 ng/100 000 cells; FSH beta/rFSH molar ratio less than 0.024). Thus, it appears that cultured rat anterior pituitary cells contain a small amount of uncombined FSH beta but that minimal quantities are released. Furthermore, GnRH may increase intracellular quantities of FSH beta but does not induce its release.