Temporal profile of neurochemical recovery following injury by transient cerebral ischemia.

The effects of transient cerebral ischemia by the four-vessel occlusion model on balance beam performance and regional activity of glutamic acid decarboxylase (GAD) and choline acetyltransferase (ChAT) and muscarinic binding (MusBnd) were evaluated over a six-month postischemia period in 6- and 24-month-old rats. Cerebral ischemia resulted in an early reduction in balance beam performance in young and old rats that partially recovered. GAD in young and old animals and ChAT in old animals and MusBnd in young and old animals were also significantly altered by ischemia. There was partial recovery of each neurochemical marker noted. In some cases the recovery was partially accounted for by the absence of any age-associated changes in the ischemic group. The results of the present study suggest an age-dependent vulnerability to ischemic injury occurs and that aged brain's gamma-aminobutyric and cholinergic systems are capable of measurable recovery.