The effects of carbenoxolone on spatial learning in the Morris water maze task in rats.

BACKGROUND

High-frequency oscillations (ripples) are proposed to be involved in memory consolidation. Ripple oscillations persist in the absence of chemical synaptic transmission and inhibitors of gapjunctions were shown to block high-frequency oscillations in hippocampal slices. In this study we investigated the effects of carbenoxolone, as a gap-junction blocker, on spatial learning in the rat. Cognitive performance was assessed using the Morris water maze (MWM).

MATERIAL/METHODS: Adult male rats were bilaterally cannulated into the CA1 region of their hippocampus. Carbenoxolone (1.23, 2.46, 4.92 microg/side), scopolamine (3 microg/side), and saline were injected through the cannulas before 4 consecutive training trials and one test trial that conducted 24 h after the training trials with the platform removed.

RESULTS

The results showed that carbenoxolone could significantly reduce the percentages of time spent, distance traveled, and entry into Q2 (the target quadrant) compared with the control group. The carbenoxolone group failed to use a selective search strategy during the final test trial, in which the platform was removed.

CONCLUSION

The results of this study suggest that carbenoxolone as a gap-junction channel blocker can decelerate the learning performances of rats in a spatial memory task, such as the MWM, that requires the integrity of the hippocampus.