Effect of hypophysectomy and growth hormone replacement on hypothalamic GHRH.
Long-term (7 and 14 days) hypophysectomy resulted in a striking decrease in growth hormone releasing hormone-like immunoreactivity (GHRH-LI) in the median eminence (ME) of adult male rats, evaluated by both radioimmunoassay and immunohistochemistry. Treatment with human GH (125 micrograms/rat, twice daily IP for 14 days) prevented, though partially, depletion of GHRH-LI from the ME, as assessed by both methods. These results demonstrate that circulating GH levels regulate the function of GHRH-producing structures, via a feedback mechanism.
D000818:Animals; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D013006:Growth Hormone / Q000494:pharmacology*; D007016:Hypophysectomy; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology*; D007106:Immune Sera; D008297:Male; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains
D007106:Immune Sera; D007987:Gonadotropin-Releasing Hormone; D013006:Growth Hormone