Effects of a new thyrotropin-releasing hormone analogue administered in rats 1 week after middle cerebral artery occlusion.

Abstract
We observed the effects of a new thyrotropin-releasing hormone analogue, YM-14673 (N alpha-[[(S)-4-oxo-2-azetidinyl]carbonyl]-L-histidyl-L-prolinamide dihydrate) on behavioral changes in 26 rats subjected to middle cerebral artery occlusion. The administration of 0.1 mg/kg i.p. YM-14673 was started 1 week after occlusion and was repeated daily for 2 weeks. YM-14673 significantly accelerated the recovery of neurologic deficits and ameliorated the disturbance of passive avoidance learning. Thus, YM-14673 improved behavioral response in a model of chronic focal cerebral ischemia. The availability of a chronic middle cerebral artery occlusion model for the evaluation of drugs is also discussed.