title: Diphenylhydantoin facilitation of labile, protein-independent memory.
abstract: Diphenylhydantoin (DPH 10(-4)M) administered subcutaneously to chicks 5 min after a one-trial passive avoidance learning task successfully counteracted amnesia induced by pretreatment 5 min before learning with ouabain or cycloheximide (CXM). Biochemical assays confirmed that in chick forebrain homogenate DPH at concentrations of 1 and 5 X 10(-4)M enhanced Na+/K+ ATP'ase activity. Since both DPH and ouabain inhibit post-tetanic potentiation, the results support the hypothesis of an initial labile phase of memory based on sodium pump (Na+/K+ ATP'ase) activity. DPH was less effective in counteracting ouabain-induced amnesia if administered later than 10 min after learning and CXM-induced amnesia if administered later than 30 min after learning. This suggests that the effect of DPH on CXM-induced amnesia is through enhancement of Na+/K+ ATP'ase activity. It was suggested that the possible hyperpolarization of membrane potential associated with sodium pump activity may serve to mark the labile memory trace, enabling formation of a more permanent trace through protein synthesis.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000647:Amnesia / Q000139:chemically induced / Q000188:drug therapy; D000818:Animals; D002645:Chickens; D003513:Cycloheximide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000187:drug effects*; D010042:Ouabain; D010672:Phenytoin / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D010042:Ouabain; D010672:Phenytoin; D003513:Cycloheximide; D000251:Adenosine Triphosphatases