The combination of several antidepressants is not synergistic on the firing of lateral septal neurons in the rat.

1. Three kinds of antidepressants (clomipramine, sleep deprivation, and electroconvulsive shock) increase the firing rate in the lateral septal neurons of the rat. 2. The acute combination of these treatments, however, did not produce added effects on firing rate of lateral septal neurons in the rat. 3. 24 hours of sleep deprivation blocked the actions of a single electroconvulsive shock. 4. It is concluded that the firstly applied treatment modifies the receptors sensitivity from the very beginning, thus blocking the action of a second treatment.