Influence of L-prolyl-L-leucyl-glycine amide on growth hormone secretion in normal and acromegalic subjects.
Melanocyte Release-Inhibiting Peptide (MRIP-I) did not affect circulating levels of ACTH, LH, FSH, TSH,ORL, betaMSH and insulin when iv infused (5.0 mg in 5 min plus 0.4 mg/min for 70-115 min), while it significantly reduced serum GH response to hypoglycemia in normal subjects and lowered serum GH levels in acromegalics. There was no correlation between the fall in serum GH after MRIP and after dopaminergic drugs in acromegaly. These data are compatible with either a direct suppressive action exerted by MRIP-I at pituitary level or an extra-pituitary effect not involving dopaminergic pathways. It can be spec-lated that since labelled MRIP-I accumualtes in the pineal and melatonin blunts GH response to hypoglycemia, the pineal gland might be involved in the MRIP-I-induced suppression of GH secretion.
D000172:Acromegaly / Q000503:physiopathology*; D000224:Addison Disease / Q000503:physiopathology; D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D002986:Clinical Trials as Topic; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D013006:Growth Hormone / Q000378:metabolism*; D006801:Humans; D007037:Hypothyroidism / Q000503:physiopathology; D007328:Insulin / Q000097:blood; D007986:Luteinizing Hormone / Q000097:blood; D009075:MSH Release-Inhibiting Hormone / Q000494:pharmacology*; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000097:blood; D010902:Pituitary Gland / Q000187:drug effects*; D010903:Pituitary Gland, Anterior / Q000187:drug effects*; D011388:Prolactin / Q000097:blood; D013972:Thyrotropin / Q000097:blood
D007328:Insulin; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013972:Thyrotropin; D013006:Growth Hormone; D009074:Melanocyte-Stimulating Hormones; D009075:MSH Release-Inhibiting Hormone