Wr. Millington et al., Localization of pro-opiomelanocortin mRNA transcripts and peptide immunoreactivity in rat heart, CARDIO RES, 43(1), 1999, pp. 107-116
Citations number
57
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Objective: alpha-Melanocyte-stimulating hormone (alpha-MSH), beta-endorphin
and other pro-opiomelanocortin- (POMC) derived peptides have been detected
in the heart, but it is uncertain whether they are synthesized by cardiomy
ocytes or by cardiac nerves innervating the heart. The objective of this st
udy was to determine whether POMC peptides are synthesized by cardiomyocyte
s. Methods: Pro-opiomelanocortin peptides were localized in rat heart by im
munohistochemistry using antisera against alpha-MSH, beta-endorphin and alp
ha N-acetyl-beta-endorphin, the predominant POMC peptides found in heart. P
ro-opiometanocortin mRNA was investigated by reverse transcription polymera
se chain reaction (RT-PCR) using primers that discriminate between full-len
gth POMC mRNA and a 5' truncated POMC transcript that is presumed to be non
-functional. Results: alpha-Melanocyte-stimulating hormone, beta-endorphin
and alpha N-acetyl-beta-endorphin immunoreactivities were localized in atri
al myocytes, particularly in the atrial appendages, but not to a significan
t extent in ventricular myocytes. Cardiac nerves were not immunostained. At
rial natriuretic peptide (ANP) immunoreactivity was similarly distributed i
n the adult heart. In neonatal heart, POMC-peptide and ANP immunoreactiviti
es were present in both atrial and ventricular myocytes. RT-PCR amplificati
on showed that full-length POMC mRNA transcripts were present in both atria
l and ventricular tissue and provide evidence that 5' truncated POMC mRNA i
s expressed in heart. Conclusions: These results support the hypothesis tha
t cardiomyocytes synthesize POMC peptides. (C) 1999 Elsevier Science B.V. A
ll rights reserved.