Involvement of physiological prolactin levels in growth and prolactin receptor content of prostate glands and testes in developing male rats.

We have investigated the role of physiological prolactin levels in the development of prepubertal male rats. Prolactin GH and testosterone levels, as well as body, ventral prostate and testicular weight, have been analysed in both control and bromocriptine-treated rats between 21 and 60 days of life. Furthermore the role of prolactin in the regulation of its own receptors has also been studied during the same period. In control rats, prolactin levels showed a prepubertal peak of secretion at 25 days of age. At this time GH and testosterone levels were low and did not show any significant variation. After this age, prolactin levels increased more gradually; determinations of GH showed great variation with low levels in most of the rats and very high values in the other animals; testosterone levels remained low until day 35 after which they increased. Simultaneously with the serum prolactin peak on day 25, a decrease in prolactin-binding capacity of ventral prostate glands, was observed and a maximum rate of body, prostate and testicular weight gain was obtained. Furthermore, in rats with pharmacologically suppressed serum prolactin levels (lower than 1 microgram/l), prolactin binding to prostate glands as well as the weight of body, ventral prostate and testes were lower than in control animals. When results were expressed in mg prostate or testes/g body weight, testes from 25-day-old treated rats weighed significantly less than controls. The later stages of development, from days 25 to 60, were characterized by an initial decline in serum prolactin levels at 29 days of age which was followed by a continuous increase until adult values were reached. During this period, prostatic prolactin receptors which were at their lowest value at 33 days of age showed a gradual rise parallel with the observed increase in plasma prolactin levels. When testicular tissue was analysed, no changes in prolactin-binding sites caused by sexual maturation were observed. The present results indicate that physiological prolactin secretion has a specific effect on the normal increase in the prostate, testes and body weight and clearly is also implicated in the regulation of its prostatic receptors at the earlier stages of development.

Levels of luteinizing hormone (LH), follicle-stimulating hormone, and 17 beta-estradiol in response to D-Trp6-LH-releasing hormone during different phases of the menstrual cycle in normal women.

PIP: The response of serum LH, FSH, and 17beta-estradiol (17b-E) to stimulation with D-Tryp6-LH-releasing hormone (LH-RH analog) was measured in 34 normal women. The analog was administered either by vein, muscle, or continuous iv infusion in doses from 1 to 50 mcg during different phases of the menstrual cycle. The increase in LH and FSH to 10 mcg analog was significant (p .05) in all phases of the menstrual cycle by 60 minutes postadministration and lasted for at least 8 hours. 17b-E increased significantly by 8 hours. LH-RH analog was 40 and 21 times more potent than LH-RH in the stimulation of LH and FSH, respectively, during the follicular phase. In the ovulatory phase, LH and FSH responses differed kinetically from their responses in the other phases, and gonadotropin release was both faster and greater. The gonadotropin responses of 3 men when compared with those of the female subjects were almost always smaller (p .05). Because of the greater potency of this LH-RH analog, it may be useful in the treatment of infertility.^ieng