Female Rats Are Less Able to Suppress Learned Fear Than Male Rats after Coronary Ischemia Reperfusion (684.11)

Anxiety is an independent risk factor for cardiovascular morbidity, particularly in perimenopausal women. We found that female rats subjected to permanent coronary artery ligation (CAL) showed an impaired ability to express recall of fear extinction, while males showed increased fear, but normal extinction memory. Females and males showed similar left ventricular dysfunction after CAL. Here, we examined effects of coronary ischemia and reperfusion (I/R), a more relevant model of human myocardial infarction, on fear extinction in male and female rats. Adult female and male Sprague Dawley rats were subjected to sham I/R or 45 min of coronary artery occlusion followed by reperfusion. Eight weeks after I/R, left ventricular function was reduced in both sexes, but males showed a larger decrease in fractional shortening and ejection fraction than females (p<0.05). Females, but not males subjected to I/R, demonstrated impaired fear extinction compared to sham‐ligated rats. Females subjected to I/R also showed increased fear during extinction recall testing compared to sham‐ligated females (P<0.05). We conclude that cycling female rats are more susceptible to the anxiogenic effect of coronary ischemia.