Estrogen-induced recovery of autonomic function after middle cerebral artery occlusion in male rats

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology Vol. 281; no. 5; p. R1531
• Main Authors: Saleh, T M, Cribb, A E, Connell, B J
• Format: Journal Article
• Language: English
• Published: United States 01-11-2001
• Subjects: Animals; Autonomic Nervous System - drug effects; Autonomic Nervous System - physiology; Baroreflex - drug effects; Baroreflex - physiology; Blood Pressure - drug effects; Blood Pressure - physiology; Brain - pathology; Disease Models, Animal; Estradiol - analogs & derivatives; Estradiol - pharmacology; Estrogen Antagonists - pharmacology; Estrogens - pharmacology; Female; Heart Rate - drug effects; Heart Rate - physiology; Infarction, Middle Cerebral Artery - pathology; Infarction, Middle Cerebral Artery - physiopathology; Male; Neuroprotective Agents - pharmacology; Rats; Rats, Sprague-Dawley
• ISSN: 0363-6119
• DOI: 10.1152/ajpregu.2001.281.5.r1531

Several studies have provided evidence to suggest that estrogen results in a significant reduction (approximately 50%) in the size of the ischemic zone in the middle cerebral artery occlusion (MCAO) model of stroke in a rat. The current study was done to demonstrate whether this estrogen-induced reduction in infarct size is associated with normalization of the autonomic dysfunction observed in an acute model of stroke in male rats. Experiments were done in anesthetized (thiobutabarbitol sodium; 100 mg/kg) male Sprague-Dawley rats instrumented to record baseline and reflex changes in cardiovascular and autonomic parameters. Estrogen was intravenously administered 30 min before, immediately before, or 30 min after MCAO. Estrogen administration resulted in a recovery of autonomic function and prevented the detrimental changes in autonomic tone observed following a stroke. In addition, infarct size was significantly increased in the presence of the estrogen antagonist ICI-182,780. These results suggest that both pre- or poststroke estrogen administration prevents or reverses acute stroke-induced autonomic dysfunction and that endogenous estrogen levels in males can contribute to this neuroprotection.