title: Amnesia-producing drugs affect hippocampal frequency potentiation.
abstract: The effects of intravenous injections of lorazepam, scopolamine and propranolol upon hippocampal potentiation produced by commissural stimulation have been investigated in rats anaesthetized with urethane. Administration of 250 micrograms/kg or 500 micrograms/kg lorazepam significantly delayed the onset of secondary potentiation (frequency potentiation) of the population spikes recorded in subfields CA1 and CA3 of the dorsal hippocampus. Scopolamine also delayed the onset of frequency potentiation in CA1, but only at high dose (10 mg/kg). No other measured parameters of frequency potentiation, paired-pulse potentiation or post-tetanic potentiation were affected by any of the drugs. Lorazepam (greater than or equal to 250 micrograms/kg) and propranolol (3 mg/kg) reduced the severity of hippocampal after-discharge. Rhythmic entrainment of after-discharges was occasionally observed. The results are discussed in relation to the possible link between hippocampal potentiation and memory processes.
mesh_terms: D000647:Amnesia / Q000139:chemically induced*; D000818:Animals; D005071:Evoked Potentials / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects*; D006801:Humans; D008140:Lorazepam / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D012601:Scopolamine / Q000494:pharmacology*
chemical_list: D011433:Propranolol; D012601:Scopolamine; D008140:Lorazepam