ELECTROPHYSIOLOGICAL ACTIVITY OF RAPHE DORSALIS SEROTONINERGIC NEURONS IN A POSSIBLE MODEL OF ENDOGENOUS-DEPRESSION

IT has been proposed that serotoninergic activity is impaired in endog enous depression. We tested this hypothesis in an experimental model, where rats which have been treated with clomipramine during the first month of life exhibit at adult age behavioural and sleep alterations w hich resemble the human disorder. Recording of serotoninergic neurones in the dorsal raphe nucleus revealed no modification of their spontan eous firing, but a reduced inhibitory response to the 5-HT re-uptake b locker citalopram in clomipramine-treated rats as compared to controls . This suggests that neonatal clomipramine treatment results in a long lasting desensitization of somatodendritic 5-HT1A autoreceptors, lead ing possibly to a dysregulation of 5-HT neurone activity in this propo sed model of depression.