[Effects of lidocaine on impairment of learning and memory function and cholinergic system caused by cerebral...

To investigate the effects of lidocaine on impairment of learning and memory function and cholinergic system caused by cerebral microsphere embolism in rats.

Healthy male Wister rats were randomly divided into the following groups. (1) Control group. (2) 600 microsphere group and 900 microsphere group, in which 600 or 900 microspheres were injected into the right internal carotid artery, respectively. (3) 600 treatment group and 900 treatment group, in which 600 or 900 microspheres were injected into the right internal carotid artery, respectively, and lidocaine was given. Water maze tasks were tested for 5 consecutive days from the 7th postoperative day. The rats were then decapitated and regions of cerebral cortex, hippocampus, and striatum were selected. The activities of choline acetyltransferase and cholinesterase and the binding activity of muscarinic receptor were determined.

(1) The latency periods were significantly longer in the 900 microsphere group than in the control group and in the 600 microsphere group. (2) The percentages of effective search strategy were significantly lower in the 600 and 900 microsphere groups than in the control group. They were significantly higher in the 600 and 900 treatment groups than in the corresponding microsphere groups. (3) The activities of choline acetyltransferase of cerebral cortex were significantly lower in the 900 microsphere and two treatment groups than in the control group. They were also significantly lower in the 600 and 900 treatment groups than in the corresponding microsphere groups. Those of striatum were all significantly lower in the microsphere and treatment groups than in the control group. (4) The activities of cholinesterase of cerebral cortex were significantly lower in the 900 microsphere group than in the control and 600 microsphere groups. They were significantly higher in the 900 treatment group than in the 900 microsphere group. Those of hippocampus were all significantly lower in the microsphere and treatment groups than in the control group. (5) The binding activities of muscarinic receptor of cerebral cortex were significantly lower in the 900 microsphere and two treatment groups than in the control group. They were also significantly lower in the two treatment groups than in the corresponding microsphere groups. Those of hippocampus and striatum were all significantly lower in the microsphere and treatment groups then in the control group. They were also significantly lower in the 600 or 900 treatment group than in the corresponding microsphere group.

Cerebral microsphere embolism caused significant and quantity-dependent impairment of learning and memory function and cholinergic system in rats. Lidocaine alleviated learning and memory dysfunction caused by cerebral microsphere embolism, but further inhibited the parameters of central cholinergic system.