TRANSIENT DECREASE IN CALBINDIN IMMUNOREACTIVITY OF THE RAT FASCIA-DENTATA GRANULE CELLS AFTER REPEATED ELECTROCONVULSIVE SHOCKS

Changes in hippocampal calbindin immunoreactivity were investigated af ter repeated electroconvulsive shocks. Adult rats were subjected to 10 , 20, or 36 electroconvulsive shocks (50 mA, 0.5 seconds), given as on shock per day, 5 days a week. The rats were sacrificed and processed for calbindin immunohistochemistry 1, 2, and 30 days after the last el ectroconvulsive shock. In the rats receiving 10 or 20 electroconvulsiv e shocks, a selective reduction of the calbindin immunoreactivity of t he dentate granule cell bodies, dendrites, and messy fibers was noted 1 and 2 days after the last electroconvulsive shock. After 36 electroc onvulsive shocks there was an almost complete loss of calbindin immuno reactivity from the granule cell bodies and dendrites, and the calbind in immunoreactivity of the messy fibers was markedly reduced. Thirty d ays after the last of 36 electroconvulsive shocks, the calbindin immun oreactivity was back to normal. Besides demonstrating pronounced chang es associated with repeated electroconvulsive shocks, the results conf irm the transient nature of these changes.