Regional brain acetylcholine kinetics: effects of reserpine.

Regional brain acetylcholine (ACh) utilization was estimated from the rate of decline in ACh content following intracerebroventricular injection of hemicholinum-3 (HC-3, 20 μg). Rats were killed by microwave irradiation at various time intervals after HC-3 injection and ACh levels measured by radioimmunoassay. ACh content declined exponentially in all brain areas, with maximum depletion occurring within 30–60 min. The relative order of cholinergic activity in the regions studied was: hippocampus striatum hypothalamus pons-medulla. Endogenous ACh content was reduced by 13–18% in all regions 24 h after injection of reserpine (5 mg/kg, i.p.). Reserpine did not alter either the utilization rates nor the extent of HC-3-induced depletion of ACh. These results indicate a general effect of reserpine on the functional storage capacity of brain ACh.