Blunted serotonin-mediated activation of the hypothalamic-pituitary-adrenal axis in chronic fatigue syndrome.

We examined 5HT1a-mediated ACTH release in patients with chronic fatigue syndrome (CFS) using a between-subjects design. Patients attending a specialist outpatient clinic for CFS, who fulfilled CDC criteria, together with age- and sex-matched healthy comparison subjects, were recruited. Subjects had a cannula inserted in a forearm vein at 0830 h and were allowed to relax until 0900 h, when baseline bloods for ACTH and cortisol were drawn. They were then given ipsapirone 20 mg PO and further blood for hormone estimation was taken at +30, +60, +90, +120 and +180 min. Baseline ACTH and cortisol levels did not differ between the two groups. Release of ACTH (but not cortisol) in response to ipsapirone challenge was significantly blunted in patients with CFS. We conclude that serotonergic activation of the hypothalamic-pituitary-adrenal axis is defective in CFS. This defect may be of pathophysiological significance.