Sleep, depression and the effects of antidepressant drugs

We have investigated the modifications of paradoxical sleep (PS) induced by antidepressant drugs acting on two different neurotransmitters, noradrenaline (NA) and serotonin (5-HT). Desipramine (DMI) decreased PS in the rat and this effect was reduced by pretreatment with alpha-methyl-paratyrosine (aMPT), but unmodified by parachlorophenylalanine (pCPA). Indalpine (IND), which inhibits specifically the reuptake of 5-HT, also decreased PS; this effect was enhanced by pretreatment with aMPT and decreased by pretreatment with pCPA. Taken together, these results suggest that DMI and IND decrease PS by enhancing the extracellular concentration of NA and 5-HT respectively. In addition, they evoke the possibility of interaction between 5-HT and NA systems, with an inhibitory effect of 5-HT on NA systems.