Effect of diazepam in circadian rhythm of activity and in novelty induced hyperactivity in the genetically hypertensive rats of Koletsky type and in the normotensive rats of Wistar strain.

The experiments were performed in the younger adult normotensive rats of Wistar strain and in the genetically hypertensive rats of Koletsky type. Motor activity was traced under regime 12 h light/12 h dark (light on at 6 A. M., light off at 6 P. M.). The activity was traced from 10 h A. M. during 24 hours by pneumoactograph described by Weggemenn. In the control genetically hypertensive males of Koletsky type phase advance was found when compared with the normotensive rats of Wistar strain. This phase advance in the former animals is missing under acute diazepam treatment (0.5 mg/kg). In control animals the novelty induced hyperactivity shows in the genetically hypertensive males of Koletsky type the lower rate of habituation than in the normotensive males of Wistar strain, i. e., the former animals show "sustained activity" in new environment. Novelty induced hyperactivity was alleviated in both strains of rats by the acute diazepam treatment; the effect of the latter drug was more expressive in the normotensive rats of Wistar strain.