男子不妊症における精漿中亜鉛濃度および総亜鉛量 --とくに前立腺分泌能との関係について--

Abstract

1)精漿中亜鉛濃度は果糖濃度と負相関し, 精嚢に対する前立腺の相対的な分泌能を反映すると考えた.一方, 前立腺分泌能の指標として精漿中総亜鉛量が適当と思われる.2)精漿中の亜鉛濃度, 総亜鉛量はともに前立腺分泌液中亜鉛濃度とは予想したような強い正相関はなかった.3)精漿中の総亜鉛量と総果糖量には相関性はなかった.4)精液所見が正常な男子と異常な男子の亜鉛レベルに有意差はなく, 精系静脈瘤や精路炎症でも特別な傾向はなかった.5)精漿中亜鉛レベルと血清中の亜鉛濃度あるいは性ホルモン濃度間に明らかな相関性はなかった.6)硫酸亜鉛を含む各種治療によっても精漿中亜鉛レベルに有意な変動はなかった.7)亜鉛濃度は前立腺分泌液>前立腺分画>精漿>精嚢分画で, 精漿中の亜鉛はほぼ特異的に前立腺より分泌されると考えた.これに対してMg, Caは一部精嚢より分泌されるようである.8)精嚢中の亜鉛は分子量3, 000以下から80, 000以上までの各物質と結合していたが, 結合物質の由来や意義は不明であった

The exact relationship between seminal plasma zinc and fertility is not known. Zinc is secreted mainly by the prostate, and zinc concentration in seminal plasma is regarded as an excellent indicator of prostatic secretory function. However, low zinc concentration may result not only from poor secretory function of the prostate but also from dilution due to excessive secretion of seminal vesicular fluid. This assumption is supported by the present result that zinc concentration was inversely correlated with fructose concentration. Therefore zinc concentration is thought to reflect prostatic function in proportion to seminal vesicular function. Total amount of zinc in seminal plasma seems to be an appropriate indicator for prostatic secretory function. In the present study, concentrations and total amount of zinc were examined in seminal plasma of men with various fertility problems. There were no significant differences between men with normal spermodiagram and those with abnormal spermodiagram, seminal inflammation or varicocele in concentration or total amount of zinc. No changes were observed in any of them after various therapies including oral zinc sulfate. However, the percentage of men with normal spermodiagram was low in the group with extremely low or high zinc concentration and total sperm count tended to increase with increase in total amount of zinc. Furthermore, the spermatozoal motility was better in the prostatic fraction than in the vesicular fraction of split ejaculates, and the percentage of men with decreased motility and normal sperm concentration was significantly high in the group with lower zinc concentration or decreased total amount of zinc. These observations indicate that prostatic secretion has a stimulatory effect on spermatozoal motility. The secretory activities of the prostate and the seminal vesicle are generally known to be closely controlled by androgens, but our findings indicate that the secretory functions of these accessory organs are independent because there was no correlation between total amount of zinc and fructose. Analysis of the relative concentrations in prostatic secretion, split ejaculates, and seminal plasma confirmed an almost exclusively prostatic origin of zinc. As part of the routine andrologic examination, measurement of concentration and total amount of zinc in seminal plasma is useful for evaluating prostatic function, but measurement of acid phosphatase, magnesium, calcium or potassium will provide almost as much information, since they also seem to be secreted primarily by the prostate.