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Disruption Of Hippocampal Multisynaptic Networks By General Anesthetics., Min-Ching Kuo, L Stan Leung

Physiology and Pharmacology Publications

BACKGROUND: Previous studies showed that synaptic transmission is affected by general anesthetics, but an anesthetic dose response in freely moving animals has not been done. The hippocampus provides a neural network for the evaluation of isoflurane and pentobarbital on multisynaptic transmission that is relevant to memory function.

METHODS: Male Long-Evans rats were implanted with multichannel and single electrodes in the hippocampus. Spontaneous local field potentials and evoked field potentials were recorded in freely behaving rats before (baseline) and after various doses of isoflurane (0.25 to 1.5%) and sodium pentobarbital (10 mg/kg intraperitoneal).

RESULTS: Monosynaptic population excitatory postsynaptic potentials at the …

Septohippocampal Gabaergic Neurons Mediate The Altered Behaviors Induced By N-Methyl-D-Aspartate Receptor Antagonists., Jingyi Ma, Siew Kian Tai, L Stan Leung

Physiology and Pharmacology Publications

We hypothesize that selective lesion of the septohippocampal GABAergic neurons suppresses the altered behaviors induced by an N-methyl-D-aspartate (NMDA) receptor antagonist, ketamine or MK-801. In addition, we hypothesize that septohippocampal GABAergic neurons generate an atropine-resistant theta rhythm that coexists with an atropine-sensitive theta rhythm in the hippocampus. Infusion of orexin-saporin (ore-SAP) into the medial septal area decreased parvalbumin-immunoreactive (GABAergic) neurons by ~80%, without significantly affecting choline-acetyltransferase-immunoreactive (cholinergic) neurons. The theta rhythm during walking, or the immobility-associated theta induced by pilocarpine, was not different between ore-SAP and sham-lesion rats. Walking theta was, however, more disrupted by atropine sulfate in ore-SAP than …