| Abstract: | Following a single injection of oestradiol benzoate (15 mug/100 g body weight) postpubertally castrated and oestrogen-primed female rats showed a distinct surge of LH secretion, while castrated and androgen-primed females displayed a diminished and delayed surge of LH secretion. On the other hand, postpubertally castrated and oestrogen-primed male rats exhibited only a slight, but significant surge of LH secretion, whereas castrated and androgen-primed males did not display any surge of LH secretion following oestrogen injection. In view of these findings the evocability of a positive oestrogen feedback action on LH secretion is dependent on the sex hormone level during the critical hypothalamic differentiation phase and the functional (priming) phase as well. |
