Animal model of anxiety: the effect of chronic bromocriptine treatment in the genetically hypertensive rats of Koletsky type and in the normotensive rats of Wistar strain.

Experiments were performed in the adult normotensive rats of Wistar strain and in the genetically hypertensive rats developed by Koletsky, i.e., in the strain where it is decreased turnover-rate of diencephalomesencephalic norepinephrine, increased CNS cholinergic activity, cholinergic supersensitivity and reduced stress resistance. The behavior in control and in drugged animals was traced in holeboard and in elevated plus-maze. In the control animals, when compared to the normotensive rats of Wistar strain, the genetically hypertensive rats of both sexes show in the first session elevated locomotor-exploratory activity, lower rate of intrassession habituation of the latter activity; in the genetically hypertensive males in the first session there is reduced percentage of time spent head dipping. The latter type of animals show lower number of entries into centre and in open arms by forepaws and by all four feet in the first session; in the first session time spent in centre and in open arms by forepaws and by all four feet is increased in normotensive males relative to hypertensive ones. Chronic Bromocriptine treatment shows in all traced parameters strain dependence. The drug only in the genetically hypertensive rats reduced total time of locomotor-exploratory activity in both sessions, elevated rate of intrasession habituation of locomotor-exploratory activity in both sessions, elevated directed exploration in hole-board in both sessions, alleviated aversion towards open space and height in the elevated plus-maze in both sessions.