Hypothalamic-pituitary function in experimental XXXX .

@entity1 @entity249 @entity251 @entity1640 @entity75 @entity1510 @entity134 @entity3566 @entity56 @entity1381 @entity35
In companion studies we have shown that chronic uremic male @entity35 are @entity249 and have lowered basal LH levels. Fertility was restored by either @entity1 @entity3566 ( @entity3566 ) or @entity251 treatment. Testicular steroidogenic responses to @entity3566 in vivo and in vitro were normal or excessive, indicating that @entity1640 was the predominant @entity75 in @entity1381 . Further studies were undertaken to characterize the nature of the central defects in regulation of pituitary LH secretion. Uremic @entity35 have reduced MCRs for @entity35 LH (rLH) (61%), @entity35 FSH (rFSH) (47%), and LHRH (41%). Pituitary gonadotropin and hypothalamic LHRH content were unchanged in uremic @entity35 . Pituitary rLH and rFSH responses to LHRH stimulation in vivo and in vitro were quantitatively normal or excessive, with delayed peaks suggesting that uremic pituitary gonadotrope secretion is deficient due to lack of appropriate hypothalamic LHRH drive rather than intrinsic pituitary defects. Despite reduced pituitary gonadotropin secretion in intact uremic @entity35 , castration induced paradoxical excessive increases in pituitary LHRH binding, serum rLH, and rFSH beyond those of nonuremic controls. Paradoxical postcastration hyperresponses of serum rLH and rFSH were not due to circulating immunoreactive fragments of gonadotropins or undernutrition. Dysfunction of the @entity1381 was further characterized in vivo by lack of rLH responsiveness to @entity1510 and @entity56 to negative testicular feedback in castrate- @entity134 -replaced and intact @entity35 . These data demonstrate that @entity1381 is principally due to aberrant hypothalamic regulation of pituitary LH secretion resembling those of the immature @entity35 or seasonally regressed animal. This recrudescence of the inactive regulatory state in a disease model suggests that common mechanisms are operative in orderly gonadal withdrawal under hostile or inappropriate environments and may underly the reversibility of @entity1 @entity1381 with successful renal transplantation.
