BASAL AND SCOPOLAMINE-EVOKED RELEASE OF HIPPOCAMPAL ACETYLCHOLINE FOLLOWING TRAUMATIC BRAIN INJURY IN RATS

This study employed in vivo microdialysis in awake, freely-moving Spra gue-Dawley rats to examine acetylcholine (ACh) release in the dorsal h ippocampus at 14 days following lateral controlled cortical impact. Ex tracellular levels of ACh were measured prior to and after an intraper itoneal administration of scopolamine (1 mg/kg), which evokes ACh rele ase by blocking autoreceptors. At 14 days post injury there were no di fferences in basal ACh levels. However, injury produced a significant reduction in scopolamine-evoked ACh release. The data suggest that cho linergic neurotransmission remains chronically compromised, and thus m ay contribute to previously documented post traumatic spatial memory d eficits.