Histologic and Physiologic Analysis of the relationship between the Dorsal Nerve of the Penis and the Corpus Cavernosum: A new tract on the innervation of penile erection?

¹Tepecik Training and Research Hospital, Urology Clinic
²Celal Bayar University, Dept of Histology
³Celal Bayar University, Dept of Physiology
⁴Bozyaka Training and Research Hospital, Urology Clinic
⁵Celal Bayar University, Dept of Urology

PURPOSE: To understand the role of the penile dorsal nerve in the erection mechanism by studying its histological and physiological relationship with the corpus cavernosum after the finding that it gives branches into the corpus cavernosum.
MATERIALS-METHODS: Ten Wistar albino rats, 4-5 months old weighing between 300-400gr were used. The rats were sorted into the electrical activity(n=6) and the intracavenous pressure(n=4) groups. Na-pentobarbital was used for anesthesia(intraperitoneal, 80-90 mg/kg). By microdissection, the dorsal nerve was prepared and hook electrodes were placed bilaterally. For intracavernous pressure measurement; poliethylen catheter washed with heparin was attached to a 23 G cannula inserted into the right corpus cavernosum.
Stimulation protocol:Monophasic square pulses generated by the stimulator were transferred via bipolar hook electrodes(amplitude 7 V, frequency 16Hz, signal duration 5msec).
Signal recording:After amplification, the pressure was recorded as numeric values. EMG signals were filtered after amplification. Filtration parameters were:10kHz Lowpass-300Hz Highpass. Signal sampling was 4000 samples/sec.
Analysis: Mean intracavernous pressure values and the amplitudes of electrical activity before and after the electrostimulation were compared as mean absolute values.
To inhibit any possible efferent interaction by the cavernous nerves, the dorsal nerve was transected more proximally and the procedure was repeated immediately.
Histologic Evaluation:Following routine fixation and parafinization, penile tissues were stained for primary antibodies against eNOS, iNOS and nNOS using indirect immunohistochemical methods. Immunereactivity was examined by two independent researchers and grouped as weak(+), moderate(++) and strong(+++).
RESULTS: After electrostimulation; the decrease in the electrical activity of the intracavernous smooth muscles and the increase in the intracavernous pressure were statistically significant. Findings were reproducable after transecting the dorsal nerve proximally prior to a second stimulation. eNOS was moderately positive(++) in vascular endothelial cells that are not only in corpus cavernosum but also in other tissues of penis. nNOS was moderately positive(++) in corpus cavernosum and in the neuron bundle that is in deep penil fasia under the tunica dartos and iNOS was observed as moderately positive(++) only in corpus cavernosum.
CONCLUSION: Dorsal nerve of the penis, far from the classical knowledge, as being solely sensorial, also has active role in the hemodynamic process of erection.

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Şekil 1

Figure 1

Dorsal sinirin elektrostimülasyonuna bağlı olarak korpus kavernosumun elektriksel aktivitesi ve kavernöz içi basınç değişimi. (1): Elektrostimülasyondan önce, (2): Elektrostimülasyon sırasında

the electrical activity and the pressure profile changes inside the corpus cavernosum related with the electrostimulation of the dorsal nerve of the penis. (1): Prior to electrostimulation, (2): During electrostimulation

Tablo 1

	Mutlak değer-ortalama EMG değerleri (mV) ± SE (n=6)	ortalama kavernöz içi basınç değerleri (mmHg) ± SE (n=4)
Stimüle edilmeden	0,6983 ± 0,083	24,20 ± 4,17
Stimülasyon halinde	0,2650 ± 0,022	35,00 ± 4,32

Elektrostimülasyon öncesi ve sonrası elektriksel aktivitedeki ve kavernöz içi basınçtaki değişimler

Table 1

	Abs-mean EMG values (mV) ± SE (n=6)	mean ICP (mmHg) ± SE (n=4)
before stimulation	0,6983 ± 0,083	24,20 ± 4,17
during stimulation	0,2650 ± 0,022	35,00 ± 4,32

The changes in the electrical activity and intracavernous pressure before and after electrostimulation