A direct effect of the pineal on the accessory sex organs in light deprived male rats.

One day after surgery groups of pinealectomized and sham-pinealectomized animals were placed in continuous darkness, and killed 0, 20, 40, 60, 80 and 100 days later. The data revealed that the sham-pinealectomized group exposed to constant darkness differs from pinealectomized group by showing lower dihydrotestosterone (DHT) concentrations, bw, accessory sex organ wt and levator ani muscle wt. No statistically significant differences were found in plasma LH, FSH and testosterone concentrations or pituitary or testes wt. The results indicated that the accessory sex organ wt were not correlated with the plasma gonadotropin and testosterone levels but they were with DHT. The data are consistent with the idea that some pineal principle acts directly on accessory sex organs in the rat.