Reduction in infarct size by local estrogen does not prevent autonomic dysfunction after stroke

Am J Physiol Regul Integr Comp Physiol. 2001 Dec;281(6):R2088-95. doi: 10.1152/ajpregu.2001.281.6.R2088.

Abstract

Systemic estrogen administration in male rats has been shown to normalize the autonomic dysfunction and reduce the infarct size after permanent middle cerebral artery occlusion (MCAO). Therefore, the present investigation determined if local microinjection of estrogen at the site of the infarct also promoted recovery of autonomic function and reduction of the infarct size. 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. The right middle cerebral artery was permanently occluded using bipolar coagulation. Local microinjection of estrogen into the insular cortex before MCAO significantly reduced the infarct size but did not attenuate the MCAO-induced autonomic dysfunction. Injection of ICI-182,780 alone significantly increased infarct area; however, the greater infarct area was not associated with enhanced autonomic dysfunction. These results suggest that within the insula, endogenous estrogen activity can affect the extent of MCAO-induced cell death, but extracortical central nervous system sites may be responsible for mediating the beneficial effects of estrogen on the autonomic disturbances.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autonomic Nervous System / drug effects
  • Autonomic Nervous System / physiopathology*
  • Baroreflex / physiology*
  • Blood Pressure / physiology
  • Brain Infarction / drug therapy*
  • Brain Infarction / physiopathology
  • Caudate Nucleus / drug effects
  • Caudate Nucleus / physiopathology
  • Estrogens / administration & dosage
  • Estrogens / pharmacology*
  • Heart Rate / physiology
  • Male
  • Microinjections
  • Middle Cerebral Artery / physiopathology
  • Phenylephrine / pharmacology
  • Pulse
  • Putamen / drug effects
  • Putamen / physiopathology
  • Rats
  • Rats, Sprague-Dawley
  • Regression Analysis
  • Stroke / physiopathology*
  • Vagus Nerve / physiopathology

Substances

  • Estrogens
  • Phenylephrine