Distribution pattern and chemical coding of sympathetic trunk ganglia neurons supplying the boar urinary bladder trigone.

Sympathetic trunk ganglia (STG) neurons projecting to the urinary bladder trigone of the boar were studied by coupling retrograde tracing Fast Blue (FB) and double-labeling immunofluorescence methods. FB-positive neurons were localized in the L1-S3 STG. Immunohistochemical staining revealed the catecholaminergic (tyrosine hydroxylase-/dopamine beta hydroxylase immunoreactivity) phenotype of the majority of FB-positive neurons, which also preferentially expressed neuropeptide Y. In addition, some of the FB-positive dopaminergic perikarya were immunoreactive for calcitonin gene-related peptide, substance P, vasoactive intestinal peptide, vesicular acetylcholine-transporter, neuronal nitric oxide synthase, somatostatin, and leu-enkephalin. Functional hypotheses have been formulated.