Gender Influences the Magnitude of the Inflammatory Response Within Embolic Cerebral Infarcts in Young Rats

Abstract

Background and Purpose The inflammatory response within cerebral infarcts may have an influence on tissue damage. Since old animals with an impaired immune response have decreased inflammation after experimental cerebral infarction, we postulated that female animals with an increased immune response will have an increased inflammatory response after cerebral infarction. Methods Embolic cerebral infarcts were produced by photochemical irradiation of the right carotid artery in 12 female Fischer rats. The inflammatory response within 4-day-old infarcts was quantitated by histology with the use of computer-assisted image analysis and compared with that in 12 male rats from a previous series. Results Severe infarcts had the most pronounced inflammatory response. Female rats had an increased inflammatory response in infarcts of all severity, which was statistically significant in severe cerebral infarcts even after adjustment for infarct size. Severe infarcts in males were significantly larger than those in females. Conclusions Gender influences the outcome of embolic cerebral infarcts after photochemical damage to the carotid artery, both in terms of the magnitude of the inflammatory response and infarct size. There are numerous gender-related differences in neurochemicals, cytokine production, and drug metabolism that may influence tissue damage after stroke and responsiveness to therapeutic intervention. The preponderance of male animals in stroke research may produce results not applicable to female stroke patients. The use of female animals will be required to provide adequate models for the study of stroke in women.