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Hossein Hosseinzadeh, Marjan Nassiri Asl, Siavash Parvardeh, Seyed Mohammad Tagi Mansouri
Med Sci Monit 2005; 11(3): BR88-94
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 gap junctions 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 µg/side), scopolamine (3 µg/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 signifi cantly 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 fi nal test trial, in which the platform was removed.
Conclusions: 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.