Specific radioimmunoassay of alpha-melanocyte-stimulating hormone in rat plasma.

A sensitive, specific and reproducible radioimmunoassay was developed for the measurement of alpha-melanocyte-stimulating hormone (alpha-MSH) in the blood plasma of rat. The assay method is based on a sensitive antiserum raised against alpha-MSH in rabbit. The serum is highly specific to alpha-MSH; a HPLC study of an extract of rat plasma showed that the immunoreactivity was given by alpha-MSH. The basal level of alpha-MSH, measured after a simple extraction with ethanol, was found to be 168.3 +/- 16.3 pg/ml (mean +/- SEM). Ether and lysine-vasopressin appeared to be potent stimuli for the peripheral release of alpha-MSH.