title: The effects of alpha 2 agonists and antagonists on hippocampal theta activity in the freely moving rat.
abstract: The alpha 2 agonists detomidine and xylazine were given to freely moving rats implanted with bilateral hippocampal recording electrodes. These alpha 2 agonists produced virtually continuous type 2 (immobility) theta. Type 1 (movement) theta was attenuated with these drugs. Subsequent administration of atropine sulfate eliminated all theta in the hippocampus. Other animals were given the alpha 2 antagonist tolazoline. This drug had no effect on type 1 theta but animals showed an increase in the production of type 2 theta during sensory stimulation. These type 2 theta responses habituated both within and between trials. Tolazoline was ineffective as a blocking agent for the effects of detomidine. Preadministration of atropine sulfate blocked the effects of detomidine on type 2 theta but not on the elimination of type 1 theta. Results are discussed in terms of alpha 2 modulation of the cholinergic and serotonergic systems.
authors.affiliation: Department of Psychology, University of Calgary, Alberta, Canada.
authors.forename: R S
authors.initials: RS
authors.lastname: Sainsbury
authors.forename: L A
authors.initials: LA
authors.lastname: Partlo
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D013826:Theta Rhythm / Q000187:drug effects*; D014043:Tolazoline / Q000494:pharmacology; D014991:Xylazine / Q000494:pharmacology
chemical_list: D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D007093:Imidazoles; D014991:Xylazine; D001285:Atropine; C041255:detomidine; D014043:Tolazoline