Mutually independent effects of adrenocorticotropin on luteinizing hormone and XXXX secretion.

@entity35 @entity251 @entity2819 @entity1176
In this study, we examined the effect of ACTH on the sensitivity of the testes to gonadotropin and determined the role of the @entity251 (T) negative feedback system in mediating the inhibitory effect of ACTH on LH secretion in adult male @entity35 . ACTH infusion for 3 days reduced basal levels of serum T and the T response to @entity1176 , but did not alter basal levels of serum LH (immunoreactive) or the LH response to @entity1176 . These effects required the presence of the adrenal glands. Infusion of @entity2819 (B) at a dose that increased serum B concentrations 9-fold had an effect similar to that of ACTH on basal serum T levels and the serum T response to @entity1176 . Basal levels of serum LH and the serum LH response to @entity1176 were not affected by B administration. These data suggest that ACTH administration reduces the sensitivity of the testes to LH, resulting in a lower basal level of T and a reduced T response to @entity1176 . This effect was independent of basal serum LH levels or the LH response to @entity1176 . It appears that B mediates the effect of ACTH on testicular sensitivity to gonadotropin. In another experiment, ACTH administration for 4 days did not alter serum LH values, but reduced serum T levels in sham-castrated male @entity35 . In contrast, ACTH treatment blunted the increase in serum LH after castration by day 2 of treatment, despite the absence of detectable levels of serum T within 6 h after castration. These data suggest that T is not essential for the inhibitory effect of ACTH on LH secretion to occur. They do not support the hypothesis that ACTH enhances the sensitivity of the hypothalamus and/or pituitary to the negative feedback effects of T.
