Size and time of hormone responses to serotonergic and noradrenergic challenge tests as related to facets of depression

Since controversial results have been reported for hormone responses to serotonergic (5-HT) and noradrenergic (NE) challenge tests in depressives, it was hypothesised that this is due to differences in depressive subgroups. Therefore the present study investigated in healthy subjects, if different aspects of depressiveness are differently related to size as well as to time of drug induced hormone responses .36 healthy male students were tested in a double blind balanced cross-over design. Their cortisol responses to 2mg of the NE reuptake inhibitor reboxetine and 30mg of the 5-HT- reuptake inhibitor citalopram were divided according to size and time of hormone responses into low and high and into early and late responders, and four questionnaire based subscales of depression were used as dependent variables. Results revealed that physical anhedonia was characterized by high and early NE responses, confirming results obtained with reboxetine in patients as well as in healthy volunteers .Social anhedonia was associated with low 5-HT responses, resembling responses of psychopaths, fatigability with early 5-HT- and NE responses and stress reactivity only with early 5-HT responses indicating perhaps specific postsynaptic receptor sensitivities or transporter polymorphisms. So the combined transmitter challenge tests can help to explain response differences of subgroups in healthy subjects by differences in receptor sensitivities related to lack of drive and emotional arousal.