Korean J Androl.  2011 Apr;29(1):21-26. 10.5534/kja.2011.29.1.21.

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

• Lee SY
• Ha MS
• Nguyen HB
• Lee JH
• Lee JH
• Myung SC
• Kim SC

• KMID: 2298622
• DOI: http://doi.org/10.5534/kja.2011.29.1.21

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.

Keyword

5-alpha reductase inhibitors; Erectile dysfunction; Ejaculation; Rabbits

MeSH Terms

5-alpha Reductase Inhibitors
Acetylcholine
Adult
Citric Acid
Contracts
Ejaculation
Electrolytes
Erectile Dysfunction
Finasteride
Fructose
Humans
Libido
Magnesium
Male
Muscle, Smooth
Nitroprusside
Norepinephrine
Oxidoreductases
Rabbits
Relaxation
Semen
Seminal Vesicles
5-alpha Reductase Inhibitors
Acetylcholine
Citric Acid
Electrolytes
Finasteride
Fructose
Magnesium
Nitroprusside
Norepinephrine
Oxidoreductases

Figure

• 

  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.

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