Effects of Castration on the Expression of Neurotrophic Factors in the Vas Deferens and Accessory Genital Glands of the Rat.

Neurotrophic factors constitute a group of growth factor families, which have important effects on survival and differentiation of neuronal cells. The neurotrophin family is composed of nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), neurotrophin (NT)3 and NT 4/5. Neurotrophins act by means of high (TrkA, TrkB and TrkC) and low (p75) affinity receptors on numerous neuronal populations of central and peripheral nervous system. The family of glial derived neurotrophic factor (GDNF) includes, besides the GDNF, neurturin (NTN), persephin (PSP) and artemin (ART). They bind to a common receptor Ret, but the binding specificity is due to a group of proteins (GFRα 1–4). These factors show a trophic effect on dorsal ganglia, motor neurons and autonomic nervous system. The aim of the present study is to evaluate the expression of NGF, BDNF and GDNF in the vas deferens and accessory genital glands of normal and castrated rats. Immunoreactivity to NGF, BDNF and GDNF was observed in all the investigated tracts. Generally, this immunoreactivity seemed to increase in castrated rats. ELISA and RT-PCR were performed to evaluate the levels of BDNF protein and its mRNA. In the normals, the greatest concentration of BDNF was observed in the vesicular gland, the lowest in the prostate. In the castrated, the BDNF concentration significantly decreased in the vas deferens. Conversely, it increased in the vesicular gland and in the ventral and dorsal prostate. BDNF transcripts were detected in both normal and castrated rats. These results suggest that neurotrophic factors are produced by the vas deferens and accessory genital glands and, in normal conditions, they are downregulated by androgens.