5-HT AGONIST-INDUCED CHANGES IN PERIPHERAL IMMUNE CELLS IN HEALTHY-VOLUNTEERS - THE IMPACT OF PERSONALITY

The present study was conducted to investigate the relationship betwee n the serotonergic neurotransmitter system and migration patterns of p eripheral lymphocytes. Altogether 40 healthy male volunteers were give n either a single dosage of the 5-HT1a-receptor agonist ipsapirone (10 mg) or a placebo (n=20 each) in a double-blind randomized trial. Bloo d samples were drawn 55, 90 and 110 min after drug intake (baseline) a nd were analyzed for the number of peripheral lymphocytes. Furthermore , saliva samples were obtained at 13 defined time points which were an alyzed for cortisol concentrations. Personality traits impulsivity, ps ychoticism and boredom susceptibility) were measured by questionnaires to investigate personality related differences in levels of serotoner gic responsiveness. Analyses of covariance indicated that ipsapirone l eads to highly significant reductions of peripheral CD4 + cells (T-hel per/inducer-cells). This was significantly correlated to the ipsapiron e-induced release of cortisol in a time-dependent manner. Furthermore, subjects scoring high on impulsivity, psychoticism and boredom suscep tibility could be identified as being more responsive to the 5-HT agon ist, indicated by their larger reduction in T-helper cells and greater cortisol release. This was hypothesized to be either due to their sub sensitivity of presynaptic or supersensitivity of postsynaptic 5-HT1a- receptors.