Structural and functional investigations of the murine cavernosal nerve: a model system for serial spatio‐temporal study of autonomic neuropathy

Abstract

used in sterile conditions. Nerve conduction velocity for the cavernosal nerve was assessed from a point 2 mm below the main (major) pelvic ganglion after stimulating the nerve at the crus penis; multi-unit averaging techniques were used to enhance the recording of slow-conduction activity. Recordings from the DNP were obtained over the proximal shaft after stimulation at the base of the penis. RESULTSStep-serial sections of the cavernosal nerve revealed numerous ganglion cells in the initial segments and gradually fewer myelinated fibres at distal levels. At the point of crural entry, the nerve contained almost exclusively unmyelinated axons. As it descended the penile shaft, the nerve separated into small fascicles containing only one to four axons at the level of the distal shaft. In the corpus cavernosum, vesicle-filled presynaptic axon preterminals were close to smooth muscle fibres, but did not seem to be in direct contact. Immunohistochemical evaluation of NOS1 activity showed intense staining of the fibres of the DNP and most of the neurones in the main pelvic ganglion. There was also scattered NOS1 activity in the nerve bundles of the corpus cavernosum. Electrophysiology identified activity in C fibres on the cavernosal nerve and in A α -A δ fibres in the DNP. CONCLUSIONThese results show that it is possible to perform integrated cavernosal pressure monitoring and ultrastructural and electrophysiological studies in this model. These yielded accurate data about the erectile status of the penis, and the state of unmyelinated and myelinated fibres in the DNP and cavernosal nerves of the same animal. This study provides a useful template for future studies of experimental diabetic autonomic neuropathy.

Regeneration of the cavernous nerve by Sonic hedgehog using aligned peptide amphiphile nanofibers

“…In order to examine the function of SHH in the pelvic ganglia and CN, electron microscopy (EM) was performed on CN’s of adult Sprague Dawley rats that had their pelvic ganglia treated bilaterally with either 5E1 SHH inhibitor (n=3, disrupts binding of SHH to its receptor Patched) or mouse IgG (n=3), which was used as a control, via Affi-Gel beads. Control CN morphology consisted of both myelinated and un-myelinated fibers depending on the distance from the pelvic ganglia [33] (Figure 2c). The myelinated fibers are distinguished from non-myelinated fibers visually by the dark myelin sheath, which surrounds the fibers and appears as a circle in cross-section.…”

Effects of hyperglycemia on rat cavernous nerve axons: A functional and ultrastructural study

“…The majority of unmyelinated fibers are postganglionic parasympathetic and sympathetic axons originating in the major pelvic ganglia (MPG). A recent ultrastructural study in control rats confirmed the abundance of postganglionic cells in the proximal segment of the CN and described the scarcity of unmyelinated fibers in the distal third of the penis shaft (Schaumburg et al, 2007). In contrast, approximately 40% of the axons in the dorsal nerve of the penis (DNP), a sensory branch of the pudendal nerve, are myelinated (Hulsebosch and Coggeshall, 1982).…”

“…As previously described (Schaumburg et al, 2007), animals were placed in the supine position, and the bladder, prostate and abdominal aorta exposed through a midline abdominal incision. ICP and status of induced erectile function were monitored in 5 of the hyperglycemic animals immediately prior to tissue harvest using procedures previously described (Christ et al, 2006; Rehman et al, 1997).…”

“…The integrity of cavernous nerve (CN) is critical for normal erectile function; even minor surgical impairment of this nerve can lead to impotence (Klotz, 2004; Walsh and Donker, 2002). The CN is principally composed of unmyelinated axons with a few scattered myelinated fibers (Schaumburg et al, 2007). The myelinated fibers range in diameter from 1–8 µm, with 2 µm as the most common value; they originate in the dorsal root ganglia (DRG) or sympathetic chain and course through the pelvic or hypogastric nerves prior to entering the CN (Dail et al, 1989; Purinton et al, 1973).…”

Visualization of prostatic nerves by polarization-sensitive optical coherence tomography

“…Birefringent property of nerves is from two sources: microtubule arrangement of nerve axons themselves and their alignment, and myelin sheath surrounding the nerve axons. The prostatic nerves consist of both myelinated and unmyelinated nerve fibers and their composition varies on different sections [66,67]. Therefore, both sources might contribute to birefringence in the prostatic nerves.…”