Immuno-electron microscopic study of tyrosine hydroxylase in the cat urinary bladder and proximal urethra

The distribution and density of tyrosine hydroxylase (TH)-immunoreactive nerves in the cat urinary bladder and proximal urethra were similar to those of glyoxylic acid fluorescent nerves. Both TH-immunoreactive and fluorescent nerve fibres markedly decreased after 6-hydroxydopamine treatment. Hence, immuno-electron histochemistry of TH was employed to investigate adrenergic termination to the muscle layers of the cat urinary bladder and proximal urethra. A total number of 3728 TH-immunoreactive axon terminals in the lower bladder body, lateral bladder base, trigone, bladder neck and proximal urethra were examined. In the bladder base (the lateral bladder base, trigone and bladder neck) and proximal urethra, most of the TH-immunoreactive axon terminals (57.1-89.2%) lay outside smooth muscle cell fascicles, while most (69.7%) in the bladder body were inside muscle cell fascicles. The proportions of TH-immunoreactive axon terminals accompanying non-TH-immunoreactive axon terminals in the five regions were almost the same (about 70%). The present study demonstrated that the mode of adrenergic termination in the bladder base and proximal urethra notably differed from that in the bladder body, and that approximately 70% of adrenergic axon terminals were associated with non-adrenergic or cholinergic axon terminals in each region.