Release of Gonadotropins Induced by Amygdaloid Stimulation in the Rat

Abstract

The amygdaloid nuclei were stimulated by iron deposits or by implanting crystalline carbachol in rats in persistent estrus induced by continuous illumination. Both electrochemical and chemical stimulation produced ovulatory response from the medial nucleus or the basolateral complex of the amygdala. Also, chemical stimulation of the bed nucleus of the stria terminalis was effective in inducing ovulation. Negative responses were observed by stimulating other areas or when the stria terminalis was found to be damaged by the electrode tract. The ovulatory response was blocked by transection of the stria terminalis but not by interruption of the ventral amygdalofugal fibers. Injection of atropine, reserpine or urethane was not effective in blocking ovulation inducedby amygdaloid stimulation. Plasma LH was found significantly higher 5 hr after chemical stimulation of the basolateral amygdaloid complex in ovariectomized rats primed with estradiol benzoate as compared to controls. Also, electrochemical amygdaloid stimulation in estrous or diestrous rats produced an increase in plasma LH. On the contrary, no effect was found in male rats whether intact or castrated and primed with estrogen or testosterone. Plasma FSH was also found to increase significantly after amygdaloid stimulation in ovariectomized estrogenprimed rats. The results are consistent with the idea that the amygdala exerts a stimulatory effect on the release of LH and FSH. (Endocrinology84: 132, 1969)