Neurohormonal responses to D-fenfluramine in healthy elderly subjects. A placebo-controlled study

Considering age-related changes in serotonin (5HT) function, we examined no rmative data of prolactin (PRL) and cortisol (CORT) responses to D-fenflura mine (D-FEN) in healthy elderly subjects. Twenty-three healthy male and fem ale volunteers aged 60-86 participated in a single-blind, placebo-controlle d, fixed-order, crossover-design challenge test. Two baseline PRL and CORT values and the responses of these hormones to 30 mg of oral D-FEN and place bo over a 4 h period were measured on two separate sessions. PRL and CORT r esponses were significantly greater following D-FEN than after placebo. Pea k PRL responses (maximum change from baseline following D-FEN) were relativ ely robust compared to peak CORT responses. Peak PRL concentration was posi tively correlated with plasma D-nor-FEN concentration. Gender and aging had no effect on hormonal responses in the elderly. Although the weight adjust ed dose used in this study was higher than the therapeutic dose of D-FEN, P RL responses were modest and only two participants experienced side effects . D-FEN is a safe serotonergic probe and PRL responsivity to D-FEN is a rel iable index of central 5HT function in the elderly. An age-related decline in serotonergic function must be considered in determining the dose require ment for maximal hormonal responses to D-FEN challenge tests in the elderly . (C) 2000 Elsevier Science Ltd. All rights reserved.