Effect of isatin, an endogenous MAO inhibitor, on acetylcholine and dopamine levels in the rat striatum.

Isatin, an endogenous inhibitor of monoamine oxidase (MAO), has several physiological properties for stress and anxiety following extensive experimental and clinical investigations. We previously identified isatin in the urine and brain of stroke-prone spontaneously hypertensive rats (SHRSP) using gas chromatography mass spectrometry. Lately, isatin was reported to have an inhibitory effect on acetylcholinesterase (AChE). This study elucidated the effect of isatin administered exogenously on the acetylcholine (ACh), choline (Ch) and dopamine (DA) levels of brain tissues in rats. Two hours after intraperitoneal administration of isatin (50 mg or 200 mg), striatal ACh, Ch and DA levels significantly increased Isatin (10(-6) M or 10(-4) M) administration through microdialysis also induced a significant increase in the ACh and DA concentration of perfusate from the rat striatum in a concentration-dependent manner. We were the first to show that isatin significantly increased ACh and DA levels in the rat striatum. These results suggest that endogenous isatin may play a role in regulating the brain levels of ACh with increasing the level of DA.