Basic scienceEffect of testosterone on the number of NADPH diaphorase-stained nerve fibers in the rat corpus cavernosum and dorsal nerve☆
Section snippets
Animal preparation
Two-month-old male Sprague-Dawley rats were divided into three groups of 10 each: castrated, control, and castrated + testosterone groups. All animals were ear-tagged for identification and housed 3 per cage. Light was maintained on a 12-hour light/dark cycle, with the dark cycle starting at 6 pm.
On day 1, the control rats underwent a sham operation (consisting mainly of scrotal exploration) and the other two groups underwent castration. At 1 and 5 weeks after surgery, the control and castrated
Apomorphine study
Castration inhibited the sexual behavior induced by apomorphine. The number of erections in 30 minutes for the castrated, control, and castrated + testosterone groups were 0, 4.8 ± 0.9, and 8.0 ± 1.6, respectively. A difference in the number of times of yawns in 30 minutes for the castrated, control, and castrated + testosterone groups were observed to be 0.5 ± 0.3, 18.8 ± 3.8, and 48.5 ± 4.5 (Fig. 1).
Electrostimulation study
The intracavernosal pressure in the castrated group, in response to electrostimulation of the
Comment
Several studies have established that NO is the principal mediator of arterial dilation and smooth muscle relaxation within the sinusoids, which bring about tumescence of penile erectile tissue.15 In vitro study has shown that electrical field stimulation of cavernosal tissue leads to an increase in NO and cyclic guanine monophosphate, and the relaxation of cavernosal smooth muscle.16 Furthermore, this response can be completely blocked by a low dose of N-nitroarginine and N-methyl-arginine,
Conclusions
The present study indicated that testosterone acts on the nervous system to mediate erection. The removal of testosterone by castration may incur downregulation of both the production and activity of NO, thereby decreasing the response to peripheral stimulation via the NO pathway.
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2023, European Urology FocusCitation Excerpt :Numerous regulatory cofactors involved in AR signaling have been identified, including those that function via direct DNA modification and those that alter cellular processes and growth [2,3]. In the corpus cavernosum, these specific signaling molecules include neuronal nitric oxide synthase (nNOS), α-1 adrenergic receptor (ADRA1A), heme oxygenase (HO), phosphodiesterase type 5 (PDE-5), and VEGF [4–8]. It is now understood that the androgen signaling axis plays a fundamental role in the physiology of male reproductive development.
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2022, Urologic Oncology: Seminars and Original InvestigationsCitation Excerpt :There is ample evidence about the influence of androgens on libido, nitric oxide synthase (NOS) production, PDE5 regulation, and cavernosal nerves function [41–43]. After castration, rat models have shown a decrease in the number and diameter of NOS-containing nerve fibers in both the corpora cavernosa and the dorsal nerves of the penis [44], revealing the regulatory effect of androgen receptors on the production and action of NO. Additionally, NOS influences PDE5 gene expression. In fact, studies have proven higher response rates to PDE5i in hypogonadal patients simultaneously treated with TRT compared to those without the therapy [45].
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Dr. Serge Carrier was supported by a grant from the Fonds de Recherche en Santé du Québec.