Effects of MK-771, A TRH analog,on pentobarbital-induced alterations of cholinergic parameters in discrete regions of rat brain

MK-771 (l-pyro-2-aminoadipyl-histidyl-thiazolidine-4-carboxamide) was administered intraventricularly to conscious and pentobarbital-narcotized rats. In the conscious rats MK-771 did not affect the regional levels of acetylcholine (ACh) or the rate of sodium-dependent high-affinity choline uptake (HACU). MK-771 was found to antagonize pentobarbital-induced elevations of ACh levels in the cortex, hippocampus and striatum. MK-771 also reversed the depressant effects of pentobarbital on the HACU of the cortex and hippocampus. Striatal HACU was unaltered by the administration of pentobarbital or the combination of pentobarbital and MK-771.