Animal model of anxiety: effect of acute diazepam treatment in the older adult genetically hypertensive rats of Koletsky type and in the older adult rats of Wistar strain.

The experiments were performed in the older adult (10-14 months of age) normotensive rats of Wistar strain and in the genetically hypertensive rats which developed Koletsky; the experiments were performed in both sexes. The behavior of control and diazepam treated rats were traced in the holeboard and in the elevated plus-maze. In the control animals when compared to the normotensive rats of both sexes show increase in total time of locomotor-exploratory activity in holeboard. In control animals the lowest level of directed exploration was found in the genetically hypertensive males. The control genetically hypertensive males show also the highest aversion towards open space and hight in the elevated plus-maze. Diazepam increases directed exploration in the genetically hypertensive rats of both sexes; directed exploration in the normotensive rats is not influenced by diazepam or this drug caused decrease. Diazepam shows no effect in between-session habituation of directed exploration in the normotensive rats of both sexes; in the genetically hypertensive rats under diazepam treatment instead of between-session habituation of directed exploration there appears in the second session elevation of directed exploration. Diazepam treatment alleviates in the first session aversion towards open space and hight in the elevated plus-maze only in the genetically hypertensive rats of both sexes and in the normotensive males. In the second session statistically significant alleviation of aversion towards open space and hight was attained in both strains of rats, in both sexes and under the both doses of diazepam. Considering the different markers of aging, stress plasma corticosterone and/or diazepam induced hypothermia show tighter age dependence in the genetically hypertensive rats than in the normotensive rats of Wistar strain. On the other hand, the effect of diazepam on aversion towards open space and hight show closer age dependence in the latter type of rats.