Effects of eicosapentaenoic acid (20:5 omega 3) on stress reactivity in rats.

This study examined the effects of eicosapentaenoic acid (EPA) on cardiovascular responses to isolation stress in male rats. Group-reared rats, on a fat-free diet, were given olive oil (OL), or EPA in OL (1.47 X 10(-7) mol/hr) via 8 week osmotic pumps, or a dummy pump (DUM), 2 weeks prior to a 4 week isolation period. Blood pressure (BP), heart rate, and body weight were monitored weekly and pressor responses to i.a. norepinephrine and angiotensin were assessed at the end of the study. BP increased during stress in all animals vs. pre-stress conditions, but was attenuated by EPA (p less than 0.001). Heart rate also increased during stress in all groups, but was greater in the EPA group (p less than 0.001). In contrast, body weight gain during stress was similar in DUM and EPA groups, but depressed by OL (p less than 0.001). Vascular response to norepinephrine was enhanced by EPA vs. DUM and OL, whereas the response to angiotensin was similar in EPA and DUM groups, but reduced by OL. These data suggest that EPA may attenuate cardiovascular responses to psychological stress.