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

Research output: Contribution to journalArticlepeer-review

Abstract

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
Volume26
Issue number6
DOIs
StatePublished - Jun 1994

Keywords

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

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

Fingerprint Dive into the research topics of 'Aging, cardiac proenkephalin mRNA and enkephalin peptides in the fisher 344 rat'. Together they form a unique fingerprint.

Cite this