Ischemic Stroke

The Big Heart Disease Lie

Heart Disease Eating Plan

Get Instant Access

A lower incidence of ischemic stroke occurs in premenopausal women compared to men.5-9 Explanations for this difference include lifestyle, vascular differences,10 direct and indirect effects of estrogen on the blood vessel wall,11-13 and other endocrine in-fluences.14 Similar sex differences in the incidence of stroke have also been documented in animal studies. For example, in one such study, a greater proportion of male gerbils showed clinical signs of stroke during a 3-hour unilateral carotid occlusion than did the females.15

The relative vulnerability of males and females to CNS tissue damage once a stroke has occurred has also been examined. Prior to the 1990s, only a few studies had addressed this issue.10,16,17 With the increased interest over the past decade, there are now numerous studies indicating that the magnitude of injury after experimental ischemia is gender-linked.15,18-20 The early studies focused primarily on survival rate and incidence of lesions following permanent carotid-artery occlusion. Berry et al.,10 for example, found that more male gerbils developed cerebral infarctions after permanent carotid-artery occlusion than did females. Following the same procedure, Payan and Conrad16 found that mortality, as well as the number of brain lesions, was significantly higher in male gerbils compared to females. Sadoshima et al.17 found that length of survival was greater for females than males after permanent bilateral carotid-artery occlusion. In addition, severe ischemic changes in the brain were seen in 50% of the males but only 15% of the females. This group also examined gender

figure 1.1 Comparison of the extent of neuronal preservation at 24 hours after ischemia (3 hours of unilateral carotid occlusion) in hippocampal CA1 and lateral cerebral cortex of male vs. female gerbils. P values were obtained using student's t test (two-tailed). (Originally published in Hall et al., J. Cereb. Blood Flow Metab, 11:292, 1991. Reproduced with permission.)

figure 1.1 Comparison of the extent of neuronal preservation at 24 hours after ischemia (3 hours of unilateral carotid occlusion) in hippocampal CA1 and lateral cerebral cortex of male vs. female gerbils. P values were obtained using student's t test (two-tailed). (Originally published in Hall et al., J. Cereb. Blood Flow Metab, 11:292, 1991. Reproduced with permission.)

differences after temporary bilateral carotid-artery occlusion and found a higher survival rate among females.

More recent studies have shown that, in addition to sex differences in survival after ischemia and occurrence of infarcts, infarct size and degree of neuronal loss also tend to be less in females than in males after ischemic injury. Hall et al.15 examined a subpopulation of stroke-prone gerbils and found that, 24 hours after an equivalent degree of severe incomplete ischemia produced by temporary unilateral carotid occlusion, males demonstrated significantly more neuronal loss in cerebral cortex and the CA1 of the hippocampus than did females. This finding is shown in Figure 1.1. Alkayed et al.,1,8 using a model of temporary (2-hour) middle-cerebral artery occlusion (MCAO), found that both Wistar and hypertensive female rats had smaller infarcts in cortex and caudate putamen than males of the same strain. Zhang et al.,19 using a similar model, also found larger infarct areas in male rats than in females. Moreover, Hall and Sutter20 reported sex differences in ischemic infarct size after permanent MCAO in mice. Once again, brain infarcts were significantly larger in males than in females.

Was this article helpful?

0 0
Your Heart and Nutrition

Your Heart and Nutrition

Prevention is better than a cure. Learn how to cherish your heart by taking the necessary means to keep it pumping healthily and steadily through your life.

Get My Free Ebook


Post a comment