Gonadotrophin release in hypogonadal and normal mice after electrical stimulation of the median eminence or injection of luteinizing hormone releasing hormone.

Electrical stimulation of the median eminence, using parameters known to cause the release of LH in normal male mice, failed to elicit any gonadotrophin response in nypogonadal (hpg) male mice. Administration of 40 ng synthetic LH releasing hormone (LH-RH) resulted in release of LH from the pituitary gland of hpg mice, although the response was significantly lower than that of normal mice. These results were consistent with the hypothesis that the hypogonadal state of the hpg mouse results from a functional basence of LH-RH in the hypothalamus rather than from a lack of response of the pituitary gland to the releasing hormone.