Effects of psychosocial stimuli on plasma renin activity in rats

The effects of two types of psychosocial stimuli on plasma renin activity (PRA) were studied in unanesthetized rats, blood being collected by decapitation. Thirty minutes of exposure to a novel environment ("open field") produced statistically significant increases of PRA in rats maintained on either a standard (1% NaCl) or sodium-free diet. No change in plasma renin substrate occurred. Prior treatment with propranolol (approximately 2 mg/kg) reduced the renin response by approximately 50% but did not completely abolish it. Plasma renin activity was also increased significantly by exposure of caged rats to the presence of a hungry cat for 30 min. We conclude that psychosocial stimuli can produce significant increases in renin secretion and that this response is mediated, at least in part, by the sympathetic nervous system.