EFFECTS OF LOSARTAN INFUSED INTO HIPPOCAMPAL CA1 AREA ON EXPLORATORY BEHAVIOUR OF RATS

The effects of the specific antagonist of angiotensin II (Ang II) type I (AT1) receptors losartan, infused uni- or bilaterally into the hippocampal CA1 area of male Wistar rats, on exploratory behaviour were examined. Microinjected bilaterally at a dose of 100 rig, losartan significantly decreased the horizontal and vertical movements (Opto Varimex apparatus). Microinjections of losartan into the left CA1 area suppressed the exploratory activity, while right-side losartan administration did not affect it, compared to the respective controls. The effect was more pronounced when losartan was infused into the left-side as compared to the right hippocampal CA1 area. The main finding was the presence of hippocampal asymmetry in exploratory behaviour to unilateral microinjections of losartan depending on the microinjected hemisphere, suggesting different distribution of AT1 receptors in left and right CA1 hippocampal area.