COMPARATIVE EFFECTS OF VALPROATE, ANXIOLYTIC, OR ANXIOGENIC DRUGS ON THE LIGHT DARK AVERSION TEST

The potential anxiolytic-like effects of 200, 300, and 400 mg/kg i.p. of sodium valproate were evaluated in the light/dark aversion test in mice. For comparison, we included the reference anxiolytic drug, diazepam (2.5, 5.0, 10 mg/kg i.p.) as well as putative anxiolytics, i.e., clonidine (0.015, 0.030, 0.060 mg/kg i.p.), verapamil (5, 10, 20 mg/kg i.p.), or anxiogenic drugs, pentylenetetrazol (5, 10, 15 mg/kg i.p.). Results showed that control mice preferred the dark compartment where they spent approximately 70% of their time. After administration of 5 and 1 0 mg/kg i.p. of diazepam or 400 mg/kg i.p. of valproate, the increase in exploratory behavior in the lit area was associated with an increase both in the number of transitions and in the time spent in the lit area. Pretreatment with 0.030 and 0.060 mg/kg i.p. clonidine caused an increase in the time spent in the lit area. Verapamil had no significant effect on both measures of this test. Pentylenetetrazol, in doses which did not cause convulsions, was anxiogenic. In conclusion, these results in the light/dark aversion test are consistent with clinical data showing that valproate, a GABA-agonist, and clonidine, an alpha-2 adrenoceptor agonist, possess anxiolytic properties.