Timing of neuroendocrine responses and effect of m-CPP and fenfluramine plasma levels in OCD.

The present study assesses the timing of and relationship between neuroendocrine response and metabolite blood levels following the partial serotonin (5-HT) agonist m-CPP and the 5-HT releaser/reuptake blocker fenfluramine. Cortisol levels peaked significantly earlier than did prolactin, m-CPP, fenfluramine, or norfenfluramine blood levels by time-to-peak analysis. This earlier cortisol response to both 5-HT agents raises the possibility that peripheral mechanisms may play a role in cortisol release. Since peak m-CPP level correlated even more closely to peak prolactin rise than did peak fenfluramine, this suggests that prolactin response to oral m-CPP challenge is useful in assessing 5-HT function.