Behavior during hippocampal microinfusions: Anticholinesterase-induced locomotor activation

Abstract

Awake, unrestrained rats received direct bilateral infusions of the cholinesterase inhibitor, echothiophate, into the dentate gyrus during a 40-min experimental session in a holeboard/activity chamber. Additional animals were similarly tested during intrahippocampal infusions of a novel cholinesterase inhibitor, NBD-AP-MPF. The computerized behavioral pattern monitor recorded the animals' locomotor activity, holepoking, and rearing in a manner that permitted the reconstruction and analysis of their sequential patterns of movement. Both echothiophate and NBD-AP-MPF infusions produced dose-dependent increases in locomotor activity that were accompanied by increased holepoking and rearing. The hyperactivity induced by anticholinesterase infusions was qualitatively similar to the atropine-sensitive effects of infusions of the cholinergic agonist, carbachol, as previously reported. Dye infusions revealed that spread of the infusate was restricted to the dentate gyrus of the anterodorsal hippocampal formation. The locomotor activation caused by the echothiophate infusions into the dentate gyrus were interpreted as indicative of a role for the cholinergic septo-hippocampal pathway in the release of motor responding.