Time course for recovery of water maze performance and central cholinergicinnervation after fluid percussion injury

This study further investigates the possible connection between postconcuss ive cognitive impairment and damage to forebrain cholinergic innervation. M oderate parasagittal fluid percussion injury was delivered to adult male ra ts. Water maze performance and synaptosomal choline uptake was measured at various times following injury. Water maze learning was severely impaired b etween 1 and 5 weeks, but recovered to normal by 10 weeks. Synaptosomal cho line uptake was significantly decreased by 15-27% in the ipsilateral hippoc ampus and parietal cortex 3 and 7 days following injury, but not by 3 weeks or thereafter. Choline acetyltransferase was also significantly decreased in the ipsilateral cortex at 3 and 7 days with subsequent recovery. This st udy shoes that parasagittal fluid percussion injury causes significant impa irment in water maze learning and ipsilateral forebrain cholinergic innerva tion. Both of these parameters recover spontaneously, but with different ti me courses.