Corticotropin-releasing factor differentially regulates proopiomelanocortin messenger ribonucleic acid levels in anterior as compared to intermediate pituitary lobes of rats.

Chronic subcutaneous infusion of small doses (0.1 microgram/h) of ovine corticotropin-releasing factor (oCRF) into rats for 8 days resulted in differential alteration of proopiomelanocortin (POMC) mRNA levels in the individual pituitary lobes: In the anterior lobe POMC mRNA levels, quantitated by hybridisation using a 32P-labelled POMC cDNA probe, increased by about 80%, whereas in the intermediate/posterior lobe a marked decrease to about 30% of the initial levels was observed. Significant changes were found not earlier than 3 days following commencement of administration.