1月30日,，《生殖生物學和內分泌》（Reproductive Biology and Endocrinology）上發(fā)表最新研究成果稱，美國北卡羅來納大學科學家發(fā)現向睪丸發(fā)射一次超聲波可能導致精子暫時停止生產,。在實驗鼠身上實施的實驗結果表明,，聲波能夠導致精子數量減少。因此科學家認為,，這種方式有可能導致人類的暫時不育,，這也將是一種新型避孕方法。
研究人員把超聲波看作是“一種有前途的避孕備選方案”,，不過他們也承認,，在真正投入臨床應用前，這種方法還需要更多的試驗,。其實,，這種方案最早提出于上世紀70年代，現在只是由美國北卡羅來納大學研究人員再次提出并得出了具體的實驗結果,。
在實驗中,，研究人員發(fā)現，兩次15分鐘的超聲波可以有效地減少精子細胞的數量,?？茖W家解釋說,，對于人類來說，當精子濃度下降到每毫升1500萬個精子時,，就可被認為是處于“亞生育能力狀態(tài)”,。實驗中的老鼠精子濃度被減少到每毫升1000萬個。
此項研究首席科學家詹姆斯-特蘇魯塔表示,，“接下來的研究需要證明,，這種避孕效果能夠持續(xù)多長時間，以及多次使用是否安全,。”研究團隊需要明確超聲波是否會產生副作用,，否則就有可能因為避孕而導致絕育。多次使用超聲波是否會對人身造成積累性損害,，這也是研究人員需要解決的問題,。
英國謝菲爾德大學男科學博士阿倫-帕塞認為，“這是一個好主意,，但是還有很多工作需要做,。使用這種方法以后，精子生產有可能會恢復,，但是精子有可能會受到損害,。精子恢復生產，出生的嬰兒仍有可能受到損害,。我們所擔心的最后一個問題是,，這種方法可能會對精子造成長久性的損傷。”(生物谷 Bioon.com)
doi:10.1186/1477-7827-10-7
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PMID:
Therapeutic ultrasound as a potential male contraceptive: power, frequency and temperature required to deplete rat testes of meiotic cells and epididymides of sperm determined using a commercially available system
James K Tsuruta, Paul A Dayton, Caterina M Gallippi, Michael G O'Rand, Michael A Streicker, Ryan C Gessner, Thomas S Gregory, Erick JR Silva, Katherine G Hamil, Glenda J Moser and David C Sokal
Background
Studies published in the 1970s by Mostafa S. Fahim and colleagues showed that a short treatment with ultrasound caused the depletion of germ cells and infertility. The goal of the current study was to determine if a commercially available therapeutic ultrasound generator and transducer could be used as the basis for a male contraceptive.
Methods
Sprague-Dawley rats were anesthetized and their testes were treated with 1 MHz or 3 MHz ultrasound while varying power, duration and temperature of treatment.
Results
We found that 3 MHz ultrasound delivered with 2.2 Watt per square cm power for fifteen minutes was necessary to deplete spermatocytes and spermatids from the testis and that this treatment significantly reduced epididymal sperm reserves. 3 MHz ultrasound treatment reduced total epididymal sperm count 10-fold lower than the wet-heat control and decreased motile sperm counts 1,000-fold lower than wet-heat alone. The current treatment regimen provided nominally more energy to the treatment chamber than Fahim's originally reported conditions of 1 MHz ultrasound delivered at 1 Watt per square cm for ten minutes. However, the true spatial average intensity, effective radiating area and power output of the transducers used by Fahim were not reported, making a direct comparison impossible. We found that germ cell depletion was most uniform and effective when we rotated the therapeutic transducer to mitigate non-uniformity of the beam field. The lowest sperm count was achieved when the coupling medium (3% saline) was held at 37 degrees C and two consecutive 15-minute treatments of 3 MHz ultrasound at 2.2 Watt per square cm were separated by 2 days.
Conclusions
The non-invasive nature of ultrasound and its efficacy in reducing sperm count make therapeutic ultrasound a promising candidate for a male contraceptive. However, further studies must be conducted to confirm its efficacy in providing a contraceptive effect, to test the result of repeated use, to verify that the contraceptive effect is reversible and to demonstrate that there are no detrimental, long-term effects from using ultrasound as a method of male contraception.
