Abstract
We have previously reported that chronic administration of not only corticosterone but also aldosterone facilitates spatial memory in adrenalectomized (ADX) rats. In the present study we investigated whether impairment effects on spatial memory occur after continuous blockade of MR, using a Morris water maze procedure to assess spatial memory abilities in ADX rats. The effect of continuous MR blockade was studied following oral administrations of aldosterone dissolved in daily drinking fluid (2.5 μg/ml) with or without injection of MR antagonist spironolactone(50 mg/kg, s.c.) twice a day for 10 days. All rats learned to locate the platform position during the training, as indicated by decreasing escape latencies. However, rats given chronic injection of spironoractone significantly decreased time spent in the platform quadrant during probe test. Furthermore, chronic spironolactone injection increased initial latency to cross the platform location. These findings suggest that continuous blockade of MR impairs spatial memory retrieval but not spatial memory learning. Therefore, continuous MR activation may be involved in spatial memory retrieval. [J Physiol Sci. 2008;58 Suppl:S136]
