Interaction of ethanol and the high pressure nervous syndrome in rats

The aim of this study was to determine whether administration of ethanol protects rats against the preconvulsive symptoms of high pressure nervous syndrome (HPNS). Male Sprague-Dawley rats were given either saline or 0.5, 1.5 or 2.5 g/kg ethanol i.p. After injection, the animals were individually exposed to helium-oxygen at 60 atmospheres absolute (atm abs) pressure. The chamber temperature was adjusted to counteract ethanol- and helium-induced hypothermia. Several behavioral parameters were scored continuously during the first 64 min after injection. The time spent in tremor at high pressure was significantly less in the 1.5 and 2.5 g/kg ethanol-treated groups. The number of jerks was significantly lower in the 2.5 g/kg ethanol-treated group. The two highest doses of ethanol induced a characteristic pattern of unsteady locomotion, which was returned to normal in the 1.5 g/kg group at 60 atm abs. Other behavioral effects of ethanol, such as depression of total motor activity, were also reduced. These results indicate that ethanol can significantly ameliorate some of the adverse symptoms of HPNS in freely moving rats.