Objective
To evaluate whether saw palmetto extract (SPE) relaxes corpus cavernosum and explore
the underlying mechanisms.
Methods
Forty Sprague-Dawley rats and 30 New Zealand rabbits were randomly allocated into
3 SPE-treated groups (low-, middle-, and high-dose) and 1 saline-treated control group.
SPE was administered intragastrically for 7 consecutive days. Another 23 rats treated
with sildenafil were used to appraise the erectile response to electrical stimulation
of nerves in the corpus cavernosum. The erectile functions of rats and rabbits were
evaluated 24 hours after the last SPE administration or 15 minutes after intragastric
sildenafil. Outcome measures included corpus cavernosum electrical activity recording,
phosphodiesterase 5 (PDE5) activity detected by the colorimetric quantitative method,
and messenger ribonucleic acid (mRNA) expression level for PDE5 and inducible nitric
oxide synthase (iNOS) determined using real-time polymerase chain reaction.
Results
In the SPE-treated animals, the relaxant response to electrical stimulation of nerves
in the corpus cavernosum, reflected by the amplitude of the electrical activity within
the cavernosum, was significantly and dose-dependently augmented. Similar effects
were observed in the sildenafil-treated rats. PDE5 activity in rat and rabbit corpus
cavernosum tissues was significantly and dose-dependently inhibited in SPE-treated
animals, whereas the iNOS mRNA level increased compared with the saline group. PDE5
mRNA, however, was only significantly enhanced in the rats treated with the middle
dose of SPE.
Conclusion
The results suggest that SPE may have potential application value for the prevention
or treatment of erectile dysfunction through an increase in iNOS mRNA expression and
inhibition of PDE5 activity in corpus cavernosum smooth muscles.
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Article info
Publication history
Published online: April 24, 2013
Accepted:
December 20,
2012
Received:
June 12,
2012
Footnotes
Surong Yang and Changrui Chen contributed equally to this work.
Financial Disclosure: The authors declare that they have no relevant financial interests.
Funding Support: This study was partly supported by Shanghai Leading Academic Discipline Project (B119) and Jiangsu Honghui Medical Co., Ltd, Nanjing, China.
Identification
Copyright
© 2013 Elsevier Inc. Published by Elsevier Inc. All rights reserved.
