[Effects of aging and ginsenoside on atrial natriuretic peptide gene expression]

We investigated the levels of atrial natriuretic peptide (r-ANP) gene expression in the atria of rats aged 2-3 months and 14-18 months. In the meantime, we studied the effects of ginsenosides on r-ANP gene expression by determining the content of ANP messenger ribonucleic acid (r-ANP-mRNA). Male and female rats were abdominally injected aqueous solution of ginsenoside (prepared from ginseng stems and leaves (G-SL) and ginseng roots (G-R) 50 mg/kg body weight, once a day, for 7 days. Atrial total RNA was extracted by cold phenol method. The specificity and relative contents of r-ANP-mRNA were determined by using Northern blot and Dot blot hybridization respectively with alpha-32P-labeled r-ANP-cDNA probe. The results showed that the r-ANF-mRNA levels in male and female rats at the age of 14-18 months were about 15% and 60% of those in male and female rats at the age of 2-3 months. G-SL and G-R increased r-ANP-mRNA contents in male rats at the age of 14-18 months by 1 fold and 1.7 folds respectively; whereas they decreased r-ANP-mRNA contents in male rats at the age of 2-3 months. No apparent effects of ginsenosides on ANP gene expression was observed in female rats. These results showed that ANP gene expression is more declined in elder rats and ginseng has certain effects in the aspect of heart endocrine to combat decrepitude.