EFFECT OF LOSARTAN MICROINJECTED INTO HIPPOCAMPAL CA1 AREA ON ANXIETY-LIKE BEHAVIOUR IN RATS

The effect of losartan (antihypertensive drug), angiotensin1 receptor (AT1) antagonist, microinjected uni- and bilaterally into the hippocampal CA1 area on anxiety of male Wistar rats was studied, using the elevated plus-maze test. It was found that bilateral microinjections of losartan (100 mu g) into CA1 area exerted anxiolytic effect. Losartan showed differential effects depending on the side of administration. Losartan infused only into the left-side increased the number of the open arms entries, prolonged the time spent there and increased the ratio open/total entries, reducing the time spent into the closed arms suggesting anxiolytic effect. These findings suggest that the inhibition of hippocampal AT1 receptors by losartan exert anxiolytic effect. The data show also an asymmetry of the AT1-related anxiolytic-like behaviour of the left and right hippocampal CA1 area, which might be due to a different distribution of AT1 receptors in the two hemispheres.