Hormonal and Subjective Responses to Intravenous m-Chlorophenylpiperazine in Women With Seasonal Affective Disorder

BACKGROUND: There is emerging evidence of serotonergic dysfunction in patients with seasonal affective disorder (SAD). We examined central serotonergic function in female patients with SAD (fall-winter pattern) by means of neuroendocrine and subjective responses to the postsynaptic serotonin receptor agonist m-chlorophenylpiperazine. METHODS: Using a double-blind, randomized, placebo-controlled design, we assessed neuroendocrine and subjective responses to m-chlorophenylpiperazine (0.1 mg/kg intravenously) and placebo in 14 unmedicated female patients with SAD in the depressed state and 15 female normal controls. All testing was done in the fall-winter months and during the follicular phase of the menstrual cycle. Plasma prolactin and cortisol levels were used as neuroendocrine measures, while subjective responses were assessed by means of visual analog scales of 10 mood states. RESULTS: On the basis of net responses to m-chlorophenylpiperazine (placebo effects subtracted from drug effects), patients with SAD exhibited blunted prolactin responses and less sadness than normal controls in response to the drug. When order of presentation of drug and placebo was taken into consideration, altered "calm" and "high" responses were also found in the patient group. CONCLUSION: Evidence of dysfunction at or downstream to central serotonergic receptors in female patients with SAD confirms and extends findings from previous research.