Distribution of cDNA for melanocortin receptor subtypes in human tissues.

Distribution of cDNA for five individual melanocortin receptor subtypes in 20 different human tissues was determined by PCR using subtype specific primers. PCR products were first visualised by agarose gel electrophoresis and ethidium bromide staining, and specific products were identified for melanocortin 1 receptor (MC1R) in pituitary and testis, for MC2R in adrenal gland, for MC3R in heart, for MC5R in adrenal gland, fat cells, kidney, leukocytes, lung, lymph node, mammary gland, ovary, pituitary, testis and uterus. The MC4R cDNA could not be detected by ethidium bromide staining. More tissues were revealed as positive when the DNA from PCR were hybridised with subtype specific radioactive probes. All the subtypes except MC4R could be detected in testis. MC4R could only be detected in pituitary. This is the first report describing the comprehensive distribution analysis of melanocortin receptor subtype cDNAs in human tissues, and provides a link between individual receptor subtype and diverse biological activities of melanocortic peptides in the respective target tissues.