Effects of precocious pinealectomy and hemicastration on pituitary and plasma LH levels in immature male rats.

In the immature male rat (7 to 28 days of age) precocious hemicastration provokes a marked compensatory testicular hypertrophy accompanied by a significant increase in pituitary LH content, and a non-significant increase in plasma LH level. In pinealectomized and sham-pinealectomized animals, hemicastration had the same effect with some exceptions at certain ages. Pinealectomy alone causes less evident changes in pituitary LH content than hemicastration. Only a transient effect was found, which was more evident in the hemicastrated rats. Plasma LH was only increased in the pinealectomized hemicastrated rats at days 16 and 18. It is concluded that pinealectomy in immature male rats seems to have only a transient stimulatory effect on pituitary and plasma LH levels, which is more striking in hemicastrated rats. So, hemicastration seems to sensitize the animals to the effect of pinealectomy.