Arginine administration inhibits hippocampal Na(+),K(+)-ATPase activity and impairs retention of an inhibitory avoidance task in rats.

In the present study we investigated the effect of acute administration of L-arginine (Arg) on hippocampal Na(+),K(+)-ATPase activity and on retrieval of step-down inhibitory avoidance in adult rats. The action of L-NAME on the effects produced by Arg was also tested. Sixty-day-old rats were treated with a single intraperitoneal injection of saline (group I, control), arginine (0.8 g/kg) (group II), L-NAME (2 mg/kg) (group III) or arginine (0.8 g/kg) plus L-NAME (2 mg/kg) (group IV). Na(+),K(+)-ATPase activity was significantly reduced in arginine-treated rats; this effect was prevented by L-NAME. Retrieval of the avoidance task was also significantly impaired by arginine, whereas the simultaneous injection of L-NAME prevented this effect. Present data strongly indicate that in vivo Arg administration reduces both Na(+),K(+)-ATPase activity and memory modulation in rats probably through NO formation.