NEUROMODULATION OF FRONTAL AND TEMPORAL CORTEX BY INTRAVENOUS D-FENFLURAMINE - AN [O-15]H2O PET STUDY IN HUMANS

This study assessed the modulatory effect of a serotonergic agonist, d -fenfluramine, on localized neuronal firing as indexed by changes in r egional cerebral blood flow (rCBF). Previously, we reported the effect of oral d,l-fenfluramine on neuronal activity as measured by change i n [F-18]fluorodeoxyglucose uptake. Improvements in the current study i nclude: a more specific serotonin agonist, d-fenfluramine; a more reli able administration route, intravenous; and a one session paradigm mad e possible with the radiotracer [O-15]H2O. Changes in relative rCBF (P < 0.001) were observed: increases within the frontal cortex bilateral ly and decreases within the temporal cortex bilaterally, and left thal amus. Other significant findings were elevated cortisol and growth hor mone; increased euphoria and panic symptoms and decreased tiredness. T hese results support further investigation with intravenous d-fenflura mine to study the net functional effects of serotonergic stimulation i n health and illness.