Reboxetine in a neuroendocrine challenge paradigm: evidence for high cortisol responses in healthy volunteers scoring high on subclinical depression

This paper investigates if the highly selective norepinephrine reuptake inhibitor reboxetine leads to a dose-dependent cortisol release and if this response depends on personality dimensions related to clinical depression in healthy volunteers. Twenty-four male subjects received placebo, 2 mg, or 4 mg reboxetine in a balanced, randomized cross-over study. Cortisol was measured in saliva at six different time-points according to the kinetics of the drug. Furthermore, several measurements of cardiovascular parameters, emotional states, and possible side-effects were obtained. Subjects were divided into two groups scoring above or below the median of a depressiveness questionnaire scale [n = 11, low (D -); n = 13, high (D +)]. Results clearly demonstrated, that reboxetine stimulates cortisol release. Whereas blood pressure was not affected, heart rate increased after 2 and 4 mg but not dose dependently. Subjects reported more non-specific arousal while the dimensions of tiredness-wakefulness and positive-negative emotional states were not affected by the drug. Somatic complaints were low and only non-specific complaints were statistically elevated but of negligible amount. Subjects classified as D + can be characterized as high responders to the drug. This is especially true not only for cortisol increases but also for changes in heart rate and some ratings on physical complaints. Hot flushes, sweating and a throbbing sensation in blood vessels in the head were observed in D + but only with the 4 mg dose. The results clearly demonstrate that reboxetine stimulates cortisol release and heart rate and that this is particularly pronounced in subjects scoring high on depression-related personality dimensions. Reboxetine, therefore, is a promising tool for investigating neuroendocrine response to noradrenergic challenge tests. The question whether increased responses in D+ are due to an up-regulation of receptor sensitivity as a consequence of low norepinephrine supply is discussed.