Desynchronization of carbachol-induced theta-like activities by alpha-adrenergic agents in guinea pig hippocampal slices.
The effect of alpha-adrenergic agents on theta-like activity (TLA) in guinea-pig hippocampal slices was studied. TLA was induced by a cholinergic agent, carbachol. TLA had a frequency of 4.66+/-0.08 Hz (mean+/-S.E.M.) and an amplitude of 96.3+/-8.3 microV in the dentate gyrus (DG). The alpha-adrenergic agents epinephrine and clonidine increased the frequency and decreased the amplitude of TLA in a concentration-dependent manner. The agents also increased antidromic and orthodromic population spike (PS) amplitudes of the granule cells, but did not have any effect on population EPSP. Another alpha-adrenergic agent, guanabentz, had the same effect as clonidine. The adenylate cyclase inhibitor SQ22536 suppressed the increase in PS amplitude by clonidine. The results suggest that these alpha2-adrenergic agents facilitate the activity of granule cells through the activation of the alpha2-adrenoreceptor and cAMP pathway, and the facilitation causes the desynchronization of TLA.
Natsume
K
K
Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Iizuka, Fukuoka, Japan. natume@bse.kyutech.ac.jp
Kometani
K
K
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D002217:Carbachol / Q000494:pharmacology*; D003000:Clonidine / Q000494:pharmacology; D018891:Dentate Gyrus / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D006143:Guanabenz / Q000494:pharmacology; D006168:Guinea Pigs; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009991:Oscillometry; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013826:Theta Rhythm / Q000187:drug effects*
D000067956:Adenylyl Cyclase Inhibitors; D000316:Adrenergic alpha-Agonists; D004791:Enzyme Inhibitors; C017759:9-(tetrahydro-2-furyl)-adenine; D002217:Carbachol; D006143:Guanabenz; D000225:Adenine; D003000:Clonidine; D004837:Epinephrine