Double labelling immunohistochemistry on the nerve fibres of retractor clitoridis muscle of the sow

Double labelling immunohistochemistry was used to study the occurrence and co-localization of tyrosine hydroxylase (TH) with several biologically active substances such as vesicular acetylcholine transporter (VAChT), neuronal nitric oxide synthase (nNOS), calcitonine gene related peptide (CGRP), leu-enkephaline (LENK), neuropeptide Y (NPY), substance P (SP) and vasoactive intestinal polypeptide (VIP) in the retractor clitoridis muscle (RCM) of adult sows. Double immunofluorescence method revealed that nerve terminals immunoreactive (IR) for the combination of TH and NPY were frequent, while the co-localization of TH with other markers were not found. Fibers singularly IR to the different tested substances were also documented. In particular, in decreasing order to density, IR to TH, NPY, CGRP, VIP, SP, VAChT, LENK were found.