Exposure to the opioid antagonist naltrexone throughout gestation alters postnatal heart development. Journal   Biology of the neonate. Citation   Biol Neonate. 82(3):207-16 Publication date   2002 Authors   McLaughlin PJ Investigators   Patricia J. McLaughlin Grant agencies   National Heart, Lung, and Blood Institute Grants   NHLBI HL-53557 MeSH headings   Heart Naltrexone Narcotic Antagonists Prenatal Exposure Delayed Effects MeSH qualifiers   growth & development administration & dosage Abstract   The influence of endogenous opioid blockade by naltrexone during prenatal life on postnatal heart development was studied in rats. Pregnant Sprague-Dawley rats received daily injections of 50 mg/kg naltrexone (NTX) or saline throughout gestation; offspring were cross-fostered at birth to mothers not receiving NTX. In general, NTX-treated offspring weighed more than controls throughout preweaning life, whereas heart weights were often increased from age-matched controls up to 35 days. Biochemical analyses of nucleic acids and protein demonstrated that DNA and protein content were increased throughout development in NTX-treated animals relative to controls. Morphometric analyses revealed increases in total area of the heart and myocardial area in NTX-exposed rats relative to control levels. These data suggest that endogenous opioids function to regulate cardiac growth during the prenatal period, and that disruption of this process has long-term implication for cardiac biology. Medline ID   22259401