Effect of muscarinic ligands on the electrical activity recorded from the hippocampus: a quantitative approach.
The electrical activity of the hippocampus was recorded from the CA 1 region in rats anaesthetized with halothane and the effects of compounds assessed following their intravenous injection. Quantification of the effects was achieved following on-line fast Fourier transformation of the signal. The electrical activity recorded from the hippocampus of the halothane-anaesthetized rat demonstrated identical characteristics to that recorded from the freely-moving animal. Three types of activity could be distinguished: rhythmical slow wave activity (RSA or theta); large amplitude slow wave activity (LIA); and small amplitude fast wave activity. Muscarinic agonists induced RSA with a consequent reduction in power. The effects were dose-dependent and were reversibly antagonized by scopolamine, but not methyl-scopolamine, indicating that the effects are mediated centrally by muscarinic receptors. The results show that, in halothane anaesthetized rats, a muscarinic RSA occurs which is unrelated to movement or behavioural arousal.
D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D001115:Arecoline / Q000494:pharmacology; D001971:Bromocriptine / Q000494:pharmacology; D004594:Electrophysiology; D006624:Hippocampus / Q000187:drug effects*; D007275:Injections, Intravenous; D008297:Male; D019832:N-Methylscopolamine; D009475:Neurons, Afferent / Q000502:physiology; D010095:Oxotremorine / Q000494:pharmacology; D010275:Parasympathetic Nervous System / Q000502:physiology; D010277:Parasympathomimetics / Q000494:pharmacology*; D051381:Rats; D011976:Receptors, Muscarinic / Q000187:drug effects*; D012602:Scopolamine Derivatives / Q000494:pharmacology; D013238:Stereotaxic Techniques
D010277:Parasympathomimetics; D011976:Receptors, Muscarinic; D012602:Scopolamine Derivatives; D001971:Bromocriptine; D001115:Arecoline; D010095:Oxotremorine; D000661:Amphetamine; D019832:N-Methylscopolamine