Experimental drugs and/or plant extracts are often dissolved in solvents, i
ncluding propylene glycol. Nevertheless, there is evidence for psychoactive
properties of this alcohol. In this study we found that in the hole-board
test 10% propylene glycol did not modify the head-dipping behavior. However
, 30% propylene glycol induced an increase in the number of head-dips (46.9
+/- 2.37 compared to 33.83 +/- 4.39, P<0.05, ANOVA/Student-Newman-Keuls),
an effect comparable to that obtained with 0.5 mg/kg diazepam (from 33.83 /- 4.39 to 54 +/- 3.8, P<0.01, ANOVA/Student-Newman-Keuls). These results d
emonstrate that 30% propylene glycol has significant anxiolytic effects in
this model and therefore cannot be used as an innocuous solvent.