Refractory hypothalamic adenylate cyclase in anorectic tumor-bearing rats: implications for NPY-induced feeding.
Although isoproterenol stimulated adenylate cyclase activity in hypothalamic membranes taken from freely-feeding, food-restricted or nonanorectic tumor-bearing rats, the response was greatly reduced in anorectic tumor-bearing rats. The addition of NPY to the membrane preparation inhibited adenylate cyclase activity in hypothalamus taken from freely-feeding and food-restricted rats, but NPY-inhibitory activity was significantly reduced in both groups of tumor-bearing rats. These results suggest that cyclic AMP formation is refractory in anorectic tumor-bearing rats, and that NPY-induced inhibition of hypothalamic adenylate cyclase is reduced in tumor-bearing rats prior to the onset of significant anorexia. Therefore, NPY-induced feeding may be reduced in tumor-bearing organisms due to a dysfunction in the cyclic AMP second messenger system.
Chance
W T
WT
Department of Surgery, University of Cincinnati Medical Center, OH 45267, USA.
Balasubramaniam
A
A
Borchers
M
M
Fischer
J E
JE
D000262:Adenylyl Cyclases / Q000187:drug effects*; D000704:Analysis of Variance; D000818:Animals; D000855:Anorexia / Q000201:enzymology* / Q000209:etiology / Q000523:psychology; D000242:Cyclic AMP / Q000096:biosynthesis; D005247:Feeding Behavior / Q000187:drug effects*; D007031:Hypothalamus / Q000187:drug effects* / Q000201:enzymology; D007545:Isoproterenol / Q000037:antagonists & inhibitors*; D008297:Male; D009478:Neuropeptide Y / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344; D012513:Sarcoma, Experimental / Q000150:complications / Q000201:enzymology* / Q000523:psychology
D009478:Neuropeptide Y; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D007545:Isoproterenol