Ischemia/reperfusion-induced changes of hypothalamic-pituitary-adrenal (HPA) activity is opioid related in Sprague-Dawley rat.

The interrelationship between the hypothalamic-pituitary-adrenal (HPA) activity and expression of central opioids is determined in ischemic Sprague-Dawley rats to support the therapeutic role of naloxone against cerebral ischemia. Two-month old rats received bilateral common carotid artery occlusion plus unilateral (right side) middle cerebral artery occlusion for 90 min under the anesthesia, and followed by reperfusion for various times. The plasma contents of adrenocorticotropin (ACTH) and RNA expression levels of proopiomelanocortin (POMC) were then determined in ischemic rats with or without naloxone treatment. Results showed that ischemia stimulates but reperfusion suppresses the activity of HPA axis. The induced expression of POMC at striatum and cortex areas appears to suppress the release of ACTH from the HPA axis. The suppression on the other hand is prevented by naloxone.