A new measure of the dopamine challenge by bromocriptine for testing personality

The dopaminergic system has been claimed to be associated with measures of Novelty Seeking, Extraversion and Positive Emotionality (Cloninger, 1997, Depue et al 1994). Furthermore, a study on transmitter responsivity and smoking had revealed that an initial increase of the prolactin (PRL) response to bromocriptine was observed in addicted as opposed to nonaddicted smokers (Netter et al 2002). Therefore the present experiment investigated if different aspects of the above personality variables are associated with the initial increase of prolactin preceding its decline upon a bromocriptine challenge. This was tested in a crossover experiment with placebo in 36 males whose prolactin plasma values were determined at 30 minutes intervals. Results revealed that subjects exhibiting the initial PRL incraese scored higher on all of the traits mentioned above than those without the peak.. This may explain why Depue et al, (1994) found a pronounced association of positive emotionality and late prolactin minima. It is discussed if the initial incraese is due to presynaptic receptor activity or special PRL agonistic DA pathways to the pituitary.