Physostigmine induces in rats a phenomenon resembling long-term potentiation.
The study dealt with a phenomenon similar to long-term potentiation of hippocampal population spikes that was observed with a high dose of physostigmine given to rats. The population spikes in the dentate granule cells in anesthetized rats were enhanced to 135, 152 and 167% of the control level 60, 120 and 240 min after the administration of physostigmine (0.1 mg/kg i.v.), respectively. The time course of the enhancement was consistent with that of blocked paired pulse inhibition by physostigmine in anesthetized rats. Such a block of paired pulse inhibition was seen at the observation of the long-term potentiation phenomenon to tetanic stimulation (100 Hz, 2 s). Perfusion of physostigmine (10(-5) M) or bicuculline (10(-6) M) elicited second spikes following the population spikes in CA1 pyramidal cells. The second spikes elicited by physostigmine were decreased by scopolamine (10(-6) M) and muscimol (5 x 10(-7) M), while those caused by bicuculline were decreased by muscimol but not by scopolamine. It is suggested that physostigmine induces a long-term potentiation-like phenomenon through a transient, abrupt increase in excitability and the subsequent block of recurrent GABAergic inhibition in the hippocampus.
Ito
T
T
Research Laboratories, Dainippon Pharmaceutical Co., Ltd., Osaka, Japan.
Miura
Y
Y
Kadokawa
T
T
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D004558:Electric Stimulation; D004594:Electrophysiology; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D009118:Muscimol / Q000494:pharmacology; D010830:Physostigmine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012601:Scopolamine / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D009118:Muscimol; D005680:gamma-Aminobutyric Acid; D010830:Physostigmine; D012601:Scopolamine; D000109:Acetylcholine; D001640:Bicuculline