Development of a radioimmunoassay for alpha-melanocyte-stimulating hormone in the rat.
A sensitive and specific radioimmunoassay for alpha-melanocyte-stimulating hormone (alpha-MSH) was developed. Extracts of the neurointermediate lobe of the rat produced displacement curves which were parallel to those obtained with synthetic alpha-MSH. The mean immunoreactive alpha-MSH concentration in neurointermediate lobes from normal adult rats was 2768 +/- 200 (S.E.M.) ng/lobe. This accounted for approximately 78% of the MSH activity of the neurointermediate lobe as measured by bioassay. Much lower levels of immunoreactive alpha-MSH were found in the anterior lobe of the rat. Extracts of rat serum and plasma also contained immunoreactive alpha-MSH and the mean level was found to be 237 +/- 20 pg/ml. This was slightly lower than the level measured in rat plasma by bioassay. Increased levels of alpha-MSH were found in plasma of rats 1 and 3 h after a single injection of trifluoperazine and after 1-5 min of ether anaesthesia. These changes were reflected by decreases in the alpha-MSH content of the neurointermediate lobe.
D000324:Adrenocorticotropic Hormone; D000818:Animals; D003366:Cosyntropin; D003429:Cross Reactions; D004986:Ether / Q000494:pharmacology; D005260:Female; D007106:Immune Sera; D007457:Iodine Radioisotopes; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000032:analysis* / Q000097:blood; D010902:Pituitary Gland / Q000032:analysis / Q000187:drug effects; D011817:Rabbits; D011863:Radioimmunoassay / Q000379:methods*; D051381:Rats; D014268:Trifluoperazine / Q000494:pharmacology
D007106:Immune Sera; D007457:Iodine Radioisotopes; D004986:Ether; D003366:Cosyntropin; D014268:Trifluoperazine; D000324:Adrenocorticotropic Hormone; D009074:Melanocyte-Stimulating Hormones