Chapter 14 Regulation of acetylcholine muscarinic receptors by embryonic septal grafts showing cholinergic innervation of host hippocampus

Abstract

Publisher Summary This chapter describes whether cholinergic innervation by embryonic septal or striatal grafts would result in the regulation of muscarinic receptors in the denervated hippocampus using quantitative autoradiography. The evidence indicates that the cholinergic input from the grafted embryonic septum also makes muscarinic synapses, as the electrophysiological responses are atropine sensitive and in aged rats transplantinduced behavioral recovery is atropine sensitive. Combined pharmacological and electrophysiological studies have shown that cholinergic synapses in the normal hippocampus are of the muscarinic type. The septo-hippocampal cholinergic projection is a particularly useful model for studying the capacity of the transplant to reinnervate the host region. Regulation of muscarinic sites after destruction of the cholinergic system innervating the cortex has been difficult to show. The results show an increase of muscarinic receptors that are shown as down regulated with appropriate cholinergic innervation by grafts of embryonic septal or striatal tissue. This work provides further evidence that the synaptic contacts made by these grafts are functional.