Quantification of the depressive effects of diazepam on the guinea pig righting reflex

The effects of 5 mg/kg/day diazepam (IP for 21-39 days) on righting reflex latency (RRL) and neuronal activity in the medial vestibular nucleus (MVN) were investigated in guinea pigs. Diazepam treatment increased the RRL relative to vehicle-injected controls (p < 0.05, ANOVA); although the average RRL in the diazepam-treated animals did decrease over time, this decrease was not statistically significant and therefore evidence of tolerance was not obtained. MVN slices were removed from diazepam-treated animals and recordings were made from MVN neurons in vitro. The average resting activities for MVN neurons in slices from diazepam-treated animals and uninjected animals from a previous study were not significantly different.