Objective: To study the dynamic function of hypothalamic 5-hydroxytryptamine receptors in patients with postviral fatigue syndrome.
Design: Prospective comparison of patients with postviral fatigue syndrome with two control groups.
Setting: Department of neurology, University of Glasgow, Southern General Hospital; department of psychiatry, St James's Hospital, Dublin.
Subjects: 15 patients with postviral fatigue syndrome, 13 age and sex matched healthy subjects, and 13 patients with primary depression.
Main outcome measures: Serum prolactin concentrations before and one, two, and three hours after administration of buspirone.
Results: Because of the effects of sex hormones on prolactin secretion data for men and women were analysed separately. There was no significant difference in baseline prolactin concentrations between patients with postviral fatigue syndrome and healthy subjects or those with primary depression. However, the percentage difference between peak and baseline values was significantly higher in patients with postviral fatigue syndrome than the control groups (one way analysis of variance: women, p = 0.003; men, p = 0.004).
Conclusions: The results suggest upregulation of hypothalamic 5-hydroxytryptamine receptors in patients with postviral fatigue syndrome but not in those with primary depression. The buspirone challenge test may therefore be useful in distinguishing these two conditions. Larger studies are required to explore the potential value of drugs acting on central 5-hydroxytryptamine receptors in the treatment of patients with the postviral fatigue syndrome.