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Female rats exposed to long (LD 18:6) or short (LD 6:18) photoperiods from 21 days of age were mated when they reached 55 days of age. On day 2 of gestation animals of each group were either pinealectomized or sham-operated. Lighting regimens were not changed during the course of the study. Male offspring of the four groups of dams were sacrificed on day 70 after birth. Rats that were maintained on long photoperiod had higher testicular testosterone, androstenedione, and dihydrotestosterone content than those raised on a LD 6:18 cycle. Whatever the breeding photoperiod used, maternal pinealectomy induced no modification of reproductive function. Among rats kept in short photoperiod, neonatal pinealectomy (on day 5 after birth) resulted in an enhanced testicular androgen content without any modification of plasma androgen concentration. These results indicate that (1) the previously reported effect of the mother's pineal on pubertal rat testicular function is not present in adulthood and (2) the pineal of the offspring is required to maintain normal testicular androgen content in the adult rat but exerts no influence on circulating androgens.

Female Sprague-Dawley rats, exposed to a long (18L:6D) or a short (6L:18D) photoperiod from 21 days of age, were mated when they reached 55 days of age. On Day 2 of gestation, dams were pinealectomized or sham-operated. Pre- and postnatal photoperiods were identical, and offspring were killed at 15 days of age. Maternal pinealectomy had no effect when rats were kept on 18L:6D. Rats born to sham-operated mothers and kept on 6L:18D had higher testicular testosterone and androstenedione content than offspring raised on the long photoperiod. This stimulatory effect of the short photoperiod was blocked by maternal pinealectomy and was not dependent on the offspring's own pineal since it was observed in both sham-operated and neonatally (on Day 5 after birth) pinealectomized rats. When sham-operated mothers housed on 18L:6D were treated daily during pregnancy and lactation by s.c. melatonin injection, there was an increase in the testicular testosterone content of offspring. It was concluded that when rats are maintained on a 6L:18D cycle the maternal pineal gland enhances the testicular testosterone and androstenedione content in 15-day-old offspring. This effect is probably mediated by maternally derived melatonin. At 15 days of age, the pineal of the offspring had no influence on testicular function.

Female rats were exposed to a short (6L:18D) photoperiod from 21 days of age. On day 2 of gestation, animals were pinealectomized or sham-operated. Lighting regimens were not changed during the course of the study. Male offspring of the 2 groups of rats were sacrificed on days 21 after birth. Pinealectomy of the mother induced the following modifications: a decrease in prostate and seminal vesicle weights, a decrease in testicular testosterone and androstenedione content and in plasma dihydrotestosterone levels. We conclude that when rats are maintained on a 6L:18D cycle the maternal pineal gland stimulates the testicular function in 21-day-old offspring.

Female Sprague-Dawley rats exposed to a short (6L:18D) photoperiod from 21 days of age were mated when they reached 55 days of age. On Day 2 of gestation animals were pinealectomized or sham-operated. On Day 5 after birth male pups of the two groups of dams were either pinealectomized or sham-operated. They were killed at 42 and 49 days of age. In offspring born to sham-operated dams and in those born to pinealectomized mothers, neonatal pineal ablation resulted in increased testicular testosterone and androstenedione content. In sham-operated and neonatally pinealectomized rats removal of the maternal pineal gland induced a decrease in testicular testosterone and androstenedione content. In contrast, after maternal pinealectomy there was a decrease in plasma testosterone and dihydrotestosterone values and testicular dihydrotestosterone content in sham-operated rats but not in those neonatally pinealectomized. We conclude that (1) the pineal glands of the mother and offspring are required to maintain normal testicular testosterone and androstenedione content in the rat, and (2) the pineal of the offspring influences the inhibitory effects of maternal pinealectomy on testicular dihydrotestosterone content and on plasma testosterone and dihydrotestosterone concentration in the offspring.

We studied the effect of hCG, aminoglutethimide and pineal effluent on the basal testosterone secretion by superfused adult rat interstitial cells. The period used to determine the mean rates of release was 120-240 min. after the start of superfusion i.e. when basal secretory rate was stable. A 2 h administration of hCG (10 mUI/ml) induced a rapid increase in testosterone output while aminoglutethimide (100 microM) decreased it. Basal testosterone release was not modified when interstitial cells were superfused with effluent of a chamber containing 1, 2 or 4 pineal glands. These results suggest that pineal secretory products exert no direct acute action on testosterone biosynthesis by rat interstitial cells.

Female rats were exposed to a short (6 L: 18 D) photoperiod from 21 days of age. On day 2 of gestation, animals were pinealectomized sham-operated. Lighting regimens were not changed during the course of the study. Male offspring of the 2 groups of rats were sacrificed on days 30, 42 and 49 after birth. Pinealectomy of the mother induced the following modifications: in 30-day-old offsprings, a decrease in prostatic weight and plasma dihydrotestosterone level; in 42-day-old rats, a decrease in prostatic weight, in testicular androstenedione and dihydrotestosterone content, and in plasma testosterone and dihydrotestosterone levels; in 49-day-old animals, decreased testicular and plasma testosterone and dihydrotestosterone levels. These results indicate that rat testicular function, after exposure to a short photoperiod beginning before conception, is decreased by maternal pinealectomy. The mother's pineal gland may play a part in the control of rat testicular function.

Pinealectomy was performed on rat foetuses aged 16.5 days +/- 8 h. Sham-pinealectomized animals were bred under the same conditions. Animals were killed when 50 or 64-days old. Plasma LH response to Gn-RH (100 ng via carotid artery) was studied in undisturbed adult male rats. 1. Body weight at birth was higher in pinealectomized rats than in sham-pinealectomized animals but, in 50 or 64-day-old body weights were not different. 2. In 50-day-old pinealectomized rats, absolute weights of testis and epididymis were higher than in sham-pinealectomized animals. When organ weights were compared to body weight by analysis of covariance, only the epididymis weight was enhanced by pinealectomy. 3. In 64-day-old animals, foetal pinealectomy did not increase reproductive organ weights. In contrast, prostate weight was decreased after pineal removal. 4. Plasma and pituitary gonadotropins were not modified by foetal pinealectomy. In undisturbed adult male rats, the plasma LH response to Gn-RH administration was identical in pinealectomized rats and in sham-pinealectomized animals. These findings may suggest an inhibitory effect of the pineal and foetal growth, but foetal pinealectomy exerts no gonadal stimulation in the adult male rats.