Detection of pro-opiomelanocortin mRNA in human and rat caudal medulla by RT-PCR.

Pro-opiomelanocortin (POMC) mRNA has been localized in the NTS of the rat, but not in the human or other species. Here, we report that RT-PCR amplification of human caudal medulla RNA generated a distinct band on agarose gels corresponding in size and sequence to the predicted 742-bp POMC PCR product. The 742-bp signal was undetectable following amplification of cortex, amygdala or caudate nucleus RNA. An homologous, 678-bp band was amplified from rat caudal medulla and, unexpectedly, from other brain regions. Competitive RT-PCR demonstrated that POMC cDNA from rat cortex, striatum and cerebellum was 17%, 22% and 45% of caudal medulla levels. These data indicate that the POMC gene is expressed in human caudal medulla and suggest that small amounts of POMC mRNA are present in regions other than the hypothalamus and NTS of rat brain.