Androgen modulation of dopamine transporter function in the corpus striatum of male rats /

Abstract

This thesis examined the relationship between the presence or the absence of testosterone on the function of the dopamine transporter system (DAT) in adult male rats. Eighteen male rats were assigned to control, castrated (GNX), and castrated with testosterone replacement (GNX+T) groups. Using an in vitro superfusion technique, the corpus striatum from each rat was divided and treated with dopamine, MPP+, and NMF infusions. Striatal dopamine and DOPAC levels were measured during baseline conditions and after drug infusion. Results of our experiments demonstrated that dopamine and DOPAC recovery were greatest in the GNX rats and were decreased in the intact or the GNX+T animals. Testosterone appears to be an important steroid that modulates the function of the DAT. Testosterone acts to enhance DAT activity while the loss of testosterone reduces DAT function. With respect to activity of neurotoxins (such as MPP+) to cause symptoms of PD, our results suggest that men may be more prone to this disease due to the facilitatory actions of testosterone on the DAT activity. Further experiments are needed to examine in detail the mechanisms of action of testosterone on DAT function and to explore the relationship DAT function and neurodegenerative diseases.