Aging, cardiac proenkephalin mRNA and enkephalin peptides in the fisher 344 rat

James L. Caffrey, Marvin O. Boluyt, Antoine Younes, Barbara A. Barron, Lydia O’neill, Michael T. Crow, Edward G. Lakatta

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54 Scopus citations


Cardiac proenkephalin (PENK) mRNA, methionine-enkephalin (ME) and leucine-enkephalin (LE) were determined from 2 days of age through senescence in Fisher 344 rats. Tissues were collected at 2 days, 2 weeks, 1, 2, 3, 7, 19, and either 22 or 27 months of age. Hearts were dissected, extracted and assaysed for ME and LE by radioimmunoassay (RIA) or for PENK mRNA by Northern blot analysis with a cDNA probe. Relative left ventricular (LV) PENK mRNA was low in 2 day animals and increased slowly between 2 weeks and 3 months of age. LV PENK mRNA then rose five to six-fold between 3 and 27 months of age. LV ME measurements were high in neonatal animals, declined to a nadir during development and then rose again as the animals matured and advanced in age. The pattern for right ventricular (RV) ME was similar. Atrial ME, also high at 2 days, declined thereafter and remained low. LE measurements in LV, RV and the atrial followed patterns similar to those described for ME. To evaluate for peptides contributed by cardiac nerves, 3, 7 and 22-month-old animals were acutely sympathectomized for 24 h with 6-hydroxydopamine. No decline in LV ME and LE was observed in the 6-hydroxydopamine treated animals. These data suggest several conclusions regarding mycardial enkephalinergic systems: (a) tissue enkephalin and PENK mRNA with advancing age, (b) tissue enkephalins may not strictly correlate with the relative abundance of PENK mRNA, and (c) most myocardial enkephalins are non-adrenergic in origin. The age-associated patterns in both PENK mRNA, ME and LE suggest that physiological, maturational or behavioral events between 3 and 7 months of age initiate the up-regulation and subsequent expansion of cardiac enkephalinergic systems.

Original languageEnglish (US)
Pages (from-to)701-711
Number of pages11
JournalJournal of Molecular and Cellular Cardiology
Issue number6
StatePublished - Jun 1994


  • Aging
  • Cardiac opioid peptides
  • Enkephalins
  • Proenkephalin messenger RNA

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine


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