Spatial pre-training attenuates hippocampal impairments in rats exposed to intermittent hypoxia

Intermittent hypoxia (IH), such as occurs in sleep apnea, is associated with increased apoptosis and neurobehavioral impairments in rats. To determine whether pre-training (P) modifies the effect of IH on spatial learning, adult male rats were trained in a spatial version of the water maze, exposed to IH or room air (RA) for 14 days, and then trained in a novel spatial task. P-RA had lower initial pathlengths than naive RA (N-RA), which were similar in P-IH and N-IH, indicating an adverse effect of IH on retention of behavioral strategies to solve the maze. However, P-IH acquired the later spatial task faster than N-IH. Pre-training was associated with increased phosphorylation of the cAMP-response element binding protein (CREB) in the hippocampus. Further, IH-induced decreases in CREB phosphorylation were attenuated by pre-training. We conclude that prior exposure to the water maze behavioral requirements attenuates the behavioral deficits occurring after IH exposure.