[The effects of ischemia and postischemic reperfusion on the brain cholinergic system of the rat]

Using experimental cerebral ischemia induced in rats with 4-vessel occlusion, the effects of 2-hour ischemia (ligation group) and 30-minute ischemia followed by 72-hour reperfusion (reperfusion group) on cholinergic system (ChS) was investigated with acetylcholine receptor (AChR), choline acetyltransferase (CAT) and acetylcholine esterase (AChE) as indicators of ChS in seven sections of the brain. The activity of CAT was reduced just after ischemia and tended to decrease further after reperfusion. CAT is known as the specific enzyme of cholinergic neuron (ChN), so the reduction of activity of CAT probably means that the ischemic change of ChN was irreversible after 30-minute occlusion. The activity of AChE was also reduced just after ischemia but tended to recover after reperfusion. AChE is not specific in ChN, so the activity of this enzyme may also reflect activity of postsynaptic neuron. The recovery tendency of AChE, therefore, may have the meaning that the ischemic change of the postsynaptic neuron was reversible. The number of AChR was found to have the tendency to increase after ischemia in more sections of reperfusion group compared with ligation group, which is supposed to show that compensatory reactive increase of the receptor may be retained after reperfusion.