AGE-DEPENDENT NEUROBEHAVIORAL RESPONSES BY YOUNG AND MATURE ADULT-RATS TO SYSTEMIC KAINIC ACID

Neurobehavioral effects caused by the excitotoxin kainic acid (KA) hav e been characterized by convulsions including 'wet dog shakes' (WDS) w ith accompanying hippocampal degeneration in experimental animals. Acc ordingly, this model has been proposed for putative excitotoxin-mediat ed disorders, such as the temporal lobe epilepsy. There have been repo rts on age-dependent neurobehavioral effects of KA; however, little is known about possible correlations between neuropathology and behavior al responses to KA. The present study demonstrates that mature adult r ats (12 months old) injected subcutaneously (s.c.) with KA (12 mg/kg) had severer damage to the hippocampal formation, i.e. CA3 region, comp ared with KA-treated young adult rats (2 months old). The mature adult animals also exhibited an earlier onset of WDS, a significantly highe r number of WDS (P>0.01), and severer convulsions compared with young adult rats. These findings indicate a positive correlation between KA- induced hippocampal damage and behavioral responses in young and matur e adult rats.