Toru Egashira, Fusako Takayama and Yasumitsu Yamanaka
Department of Pharmacology, Oita Medical University, 1-1, Idaigaoka, Hasama-machi, Oita 879-55, Japan
Abstract: Cerebral hypoperfusion was chronically induced in aged rats via permanent bilateral occlusion of common carotid arteries (2VO). Marked reduction of the Bmax value of the muscarinic receptors (mAChR) in both the cortex and striatum and the Vmax value of choline acetyltransferase (ChAT) activity in the cortex, hippocampus and striatum were observed as compared with those of control aged rats. No significant changes in mAChR and ChAT activity were observed between young control rats and young 2VO rats. One month post-surgery in aged rats, daily doses of bifemelane (10 mg/kg) or aniracetam (50 mg/kg) were administered orally over a 4-week period. Administration of bifemelane significantly increased Bmax values and decreased apparent Kd values for 3H-quinuclidinyl benzilate (QNB) in mAChR in the striatum. Chronic administration of bifemelane or aniracetam also enhanced ChAT activity in the cortex, hippocampus and striatum. In particular, administration of bifemelane resulted in a significant increase in Vmax values of ChAT in all three brain regions, while no significant change in Km values for ChAT was observed. These results suggest that bifemelane is responsible for this activity, thereby enhancing the functioning system of CNS cholinergic neurons of cerebral hypoperfused aged rats.
Keywords:
Aged rat, Permanent bilateral occlusion of common carotid arteries, Muscarinic receptor,
Choline acetyltransferase, Bifemelane, Aniracetam