The Effects of 5-alpha Reductase Inhibitor on Contraction of Erectile Tissue and Secretion of Seminal Fluid in Male Rabbits: Preliminary Study

Shin Young Lee; Moon Soo Ha; Hoai Bac Nguyen; Joo Hyoung Lee; Jang Hee Lee; Soon Chul Myung; Sae Chul Kim

doi:10.5534/kja.2011.29.1.21

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Lee, Ha, Nguyen, Lee, Lee, Myung, and Kim: The Effects of 5-alpha Reductase Inhibitor on Contraction of Erectile Tissue and Secretion of Seminal Fluid in Male Rabbits: Preliminary Study

Original Article

Korean J Androl 2011;29(1):21-26.

Published online: 22 April 2011

DOI: https://doi.org/10.5534/kja.2011.29.1.21

The Effects of 5-alpha Reductase Inhibitor on Contraction of Erectile Tissue and Secretion of Seminal Fluid in Male Rabbits: Preliminary Study

Shin Young Lee¹, Moon Soo Ha², Hoai Bac Nguyen², Joo Hyoung Lee³, Jang Hee Lee³, Soon Chul Myung², Sae Chul Kim²

¹Department of Urology, Seoul Medical Center, Korea

²Chung-Ang University College of Medicine, Seoul, Korea

³Bioculture, Cheonan, Korea

Received 15 February 201124 March 2011 Accepted 29 March 2011

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Purpose

Adverse sexual experiences such as erectile dysfunction (ED), loss of libido, and ejaculation disorders have been consistent side effects of 5-alpha reductase inhibitors (5ARI). The aim of this study was to evaluate the effects of 5ARI (finasteride) treatment on semen parameters and contraction of the corpus cavernosum and seminal vesicles in male rabbits.

Materials and Methods

Adult male New Zealand White rabbits (n=10) were randomized into 2 groups: finasteride-treatment (5ARI) group and vehicle-treatment (control) group. The 5ARI group received daily oral finasteride (10 mg/day) by gavage for 4∼6 weeks, and the control group received the same concentration of the vehicle. The semen volume and semen parameters between the 2 groups were compared; thereafter, contraction or relaxation responses of smooth muscle strips of the corpus cavernosum and seminal vesicles were observed in an organ bath.

Results

Semen magnesium (14.2 vs 5.1 mg/dl) and protein (2.2 vs 1.6 g/dl) concentrations were significantly lower in the 5ARI group than in the control group. The concentrations of other parameters such as electrolytes (Na/K/Cl), fructose, and citrate did not differ between the 2 groups. The contractile responses to norepinephrine (NE) significantly increased in the 5ARI group compared to the control group and the relaxation responses to acetylcholine (ACh) or sodium nitroprusside (SNP) also increased in the 5ARI group. The contractile responses of the seminal vesicular strips to NE significantly decreased in the 5ARI group compared with the control group.

Conclusions

The results suggest that finasteride may decrease contraction of seminal vesicle tissue and alter semen parameters. The effect of finasteride on erectile tissue was double-faced; enhancing both contraction and relaxation. Further study is needed in this respect.

Keywords: 5-alpha reductase inhibitors, Erectile dysfunction, Ejaculation, Rabbit

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Fig. 1.

Comparison of contraction by norepinephrine 10⁻⁵ M on rabbit corpus cavernosal strip according to finasteride medication (n=12, Asterisk indicates p-value is ＜0.05). Error bars indicate mean±standard error.

Fig. 2.

Comparison for the effect of finasteride medication on rabbit corpus carvernosal strips relaxation in an acetylcholine dose-dependent manner. The preparation were pre-constricted with 10⁻⁵ M norepinephrine (n=12, Asterisk indicates p-values are ＜0.05). Error bars indicate mean±standard error.

Fig. 3.

Comparison for the effect of finasteride medication on rabbit seminal vesicle strips contraction in norepinephrine dose-dependent manner (n=12, Asterisk indicates p-values are ＜0.05). Error bars indicate mean±standard error.

Table 1.

Comparison of semen parameter according to finasteride medication

		Protein (g/dl)	Albumin (g/dl) Mg (mg/dl)	Na (mEq/l)	K(mEq/l)	Cl (mEq/l)	Fructose (mg/dl)	Citrate (g/l)
Control group	Pre-medication	2.1±0.8	0.7±0.3 10.3±8.1	172±11.0	20±13.7	88±33.6	868±368.7	3.51±1.6
	Poste-medication	2.2±0.6	0.8±0.2 11.8±8.1	151.3±12.2	24.7±5.0	71.3±7.3	1,569±642.7	5.64±0.8
5ARI group	Pre-medication	2.2±0.5	0.7±0.2 14.2±7.5	182±19.9	16±4.9	95±25.9	707±266.3	2.5±1.8
	Post-medication	1.6±0.5∗	∗ 0.5±0.2 5.1±3.2∗	170.6±15.5	19.4±3.8	88.3±24.4	2,028±981.0	5.16±0.9
		Sperm viability (%)			Sperm concentration (10⁸)
Control group	Pre-medication	88.3±5.8			4.8±2.8
	Post-medication	83.3±15.7			2.0±0.9
5ARI group	Pre-medication	85.0±5.0			6.5±2.6
	Post-medication	80.7±12.1			2.9±2.1

Data expressed mean±SD (standard deviation). ∗p＜0.05.

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