Paradoxical Sleep Deprivation and the Immobility Response in the Rat: Effects of Desipramine and Phentolamine

A series of experiments was conducted on the presumption that instrumental deprivation of paradoxical sleep (PS) has an effect comparable with that of antidepressant drug treatment in a behavioral paradigm, Porsolt's forced swim test. After long-term PS deprivation, we studied the duration of immobility, which can be markedly reduced by antidepressant drugs, using both the platform and the pendulum technique. In addition to a small common effect for PS deprivation, differences confirming the platform-pendulum controversy were also detected. Nonspecific platform effects are considered to explain these differences. In a second experiment it was shown that the small PS deprivation effect can be enlarged by desipramine treatment, suggesting similarities in the underlying mechanisms. In the third experiment, just before the end of the deprivation, phentolamine, a drug that blocks the rebound of PS, was administered. It reduced the effect of pendulum PS deprivation, suggesting that PS propensity is an important factor in the reduction of duration of immobility.