Elsevier

Brain Research

Volume 455, Issue 1, 5 July 1988, Pages 110-114
Brain Research

Evidence that activation of in vitro hippocampal θ rhythm only involves muscarinic receptors

https://doi.org/10.1016/0006-8993(88)90119-9Get rights and content

Abstract

The present study was conducted for two purposes: the first was to evaluate whether activation of nicotinic receptors in the hippocampal formation in vitro (slice) preparation was capable of producing type 2 (atropine-sensitive) θ rhythm. The cholinergic nature and involvement of muscarinic receptors in this type of θ has been previously well documented. The second purpose was to determine whether perfusion of a number of (other) putative neurotransmitters shown to be present in the hippocampal formation could elicit type 1 (atropine-resistant) θ in the slice preparation. Further experiments were conducted to determine if these agents interacted in any manner with cholinergically-induced type 2 θ. Electroencephalic (EEG) θ activity was not induced by nicotine, providing evidence for an exclusive muscarinic receptor involvement in this cholinergically-induced type 2 θ. In addition, θ activity was not elicited by the application of γ-aminobutyric acid (GABA), glutamate, norepinephrine, dopamine or serotonin. The application of any of these agents did not significantly alter the production of cholinergically-induced θ. These results suggest that type 1 θ originates in regions extrinsic to the hippocampus, or is the result of the interaction of several neurotransmitters on different receptors.

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*

Present address: Department of Animal Physiology, The University of Lodz, Poland.

**

Present address: Department of Psychology, The University of Calgary, Canada.

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