Conditioning of Rats to Tumbling Trauma by Electroconvulsive Shock

Rats were made relatively resistant to the lethal effects of tumbling trauma by a previous series of electroconvulsive shocks (ECS). ECS causes an immediate marked rise in the plasma concentrations of adrenaline and noradrenaline, as a result of the electrical stimulation of the sympathetic nervous system. The plasma concentrations of adrenaline and noradrenaline, which are elevated in response to trauma, show a more rapid fall after termination of trauma in the ECS-conditioned animals than in controls. There is no significant alteration in the sensitivity of ECS-conditioned rats to toxic doses of adrenaline and noradrenaline. It is thought that ECS-conditioning, and probably also the conventional drum-conditioning, are brought about by a diminished reactivity of the sympathetic nervous system after its repeated stimulation.