Has active immunization against gonadotrophin-releasing hormone any effecton testis innervation in the pig? - An immunohistochemical study

The innervation of porcine testes was studied in intact animals and in boar s undergoing active immunization against gonadotrophin-releasing hormone (G nRH) by means of immunohistochemistry using antibodies to tyrosine hydroxyl ase (TH), dopamine P-hydroxylase (D beta H), vasoactive intestinal polypoly peptide (VIP), neuropeptide Y (NPY), synaptosome-associated protein of 25 k Da (SNAP 25) and protein gene product 9.5 (PGP 9.5). Moreover, the distribu tion of luteinizing hormone (LH) receptors in clusters of Leydig cells was also investigated. To identify these cells easily, either the NADPH diaphor ase histochemical technique or the Mayer counterstaining procedure was appl ied. Differences in the distribution pattern and relative density of partic ular subsets of intratesticular nerve fibres were observed in immunized boa rs as compared to those found in the intact animals. In the testes of non-t reated animals, only single TH-immunoreactive (TH-IR) nerve fibres were obs erved. However, many DBH-IR nerve terminals surrounded blood vessels in the tunica albuginea and parenchyma. Very scarce VIP-IR nerves occurred only i n the tunica albuginea, mainly in close vicinity to blood vessels. Immunore activity to NPY occurred in single nerve fibres. Immunoreactivity to SNAP-2 5 and PGP 9.5 was found in single nerve fibres distributed mainly in the tu nica albuginea. The interstitial cells were heavily stained for LH-receptor s and NADPH-diaphorase. In the testes of immunized animals, only single TH- IR nerve fibres, scattered mainly in the tunica albuginea, were observed. S ome TH-IR nerve terminals were also encountered in the parenchyma of the or gan, where they were always associated with blood vessels. D beta H-IR nerv e fibres formed a dense network distributed throughout the testis in associ ation with the capsule, vasculature and interstitium. Some fibres were obse rved to run between seminiferous tubules. VIP-IR nerve fibres were located in the neighbourhood of blood vessels in the tunica albuginea and parenchym a. Only single VIP-IR nerves were found between seminiferous tubules. Numer ous NPY-IR nerve fibres occurred in the tunica albuginea and parenchyma of the organ. SNAP-25-IR and PGP 9.5-IR nerve terminals formed a dense network distributed throughout the testis and many fibres were observed between se miniferous tubules. Interstitial cells were very weakly stained for LH rece ptors or NADPH-diaphorase.