犬精漿基質金屬蛋白酵素2及9之分析

Abstract

精漿包含許多由睪丸、前列腺、及其他附屬性腺細胞來源的蛋白酶，如膠原蛋白酶樣胜肽酶（collagenase-like peptidase）、明膠分解蛋白酶（gelatinolytic proteinases）、胞漿素原活化劑（plasminogen activator）、第二型胃蛋白酶原（pepsinogen II）、Pz-胜肽酶（Pz-peptidase）及前列腺特殊抗原。基質金屬蛋白酵素（matrix metalloproteinases, MMPs）是屬於蛋白溶解酵素家族之一，並且包含了膠原蛋白酶樣胜肽酶及明膠分解蛋白酶。MMPs可分解細胞外基質及基底膜上的蛋白質；此特性可能與細胞增生、移形、分化、血管新生、凋亡及宿主防禦相關的細胞活動有關。先前文獻已證實，在人的精漿中有MMP-2（72 kDa）及MMP-9（92 kDa）兩種MMPs，並且亦少述探討各種MMPs存在於犬隻精漿的文獻。然而，此類MMP濃度與精液品質之間的關係仍為目前未釐清的課題。本研究目的在評估犬精液樣本中，非活化態（latent）與活化態（active）MMP-2及MMP-9活性和影響精液品質的相關因子之間是否具有相關性。本研究結果發現非活化態與活化態MMP-2及MMP-9皆存在於犬精液樣本(=49)中，並且以非活化態的形式存在為主；而在與精液品質的關係上，具有低精子濃度、低總精子數、低正常形態精子數、低正常形態活精子數的樣本中，非活化態與活化態的MMP-9的活性皆較高。此外，非活化態MMP-9活性和總精液量、精子總存活數、正常形態的活精子百分比數值間呈現負相關。非活化態MMP-2和總精液量、精子存活百分比與正常形態精子數間同樣呈現負相關；活化態MMP-2則和具有活動力精子數與具有活動力且具有正常型態的精子數呈現負相關。本實驗指出proMMP-9和MMP-9的活性可能是精液品質低下繁殖力之原因或造成之結果。由於MMP-2活性和精子的高運動性有緊密關係，因此進一步研究有待證實MMP-2的活性是否可用來評估精子功能或當成雄性繁殖能力之有效指標。

Seminal plasma contains many proteinases originating from testicular cells, prostate and other accessory sex glands, such as collagenase-like peptidase, gelatinolytic proteinases, plasminogen activator, pepsinogen II, Pz-peptidase and prostatic specific antigen. The matrix metalloproteinases (MMPs), which contain collagenase-like peptidase and gelatinolytic proteinase activities, are a family of proteolytic enzymes that degrade protein components of the extracellular matrix and basement membrane. Therefore, they might be involved in cell behaviors such as cell proliferation, migration, differentiation, angiogenesis, apoptosis and host defense. Previous studies have shown that MMP-2 and MMP-9, known as 72 kDa and 92 kDa gelatinase or type Ⅳ collagenase respectively, were presented in human seminal plasma. One of the main questions is whether the levels of MMPs are associated with semen traits. Following the line of research, only few studies have been focused on the presence of MMPs in canine seminal plasma. Aims of this study were to evaluate the latent and active forms of MMP-2 and MMP-9 in this species and to investigate their association with semen parameters. The results (n=49) have shown that both latent and active forms of MMP-2 and MMP-9 were present in canine seminal plasma, and latent forms were the predominant proteins. Interestingly, the high latent and active forms of MMP-9 activity were elevated in semen with low sperm count of concentration, normal morphology, and normal live sperm. Furthermore, there were inverse correlation between the levels of proMMP-9 with semen volume, total count of vital sperm, and % normal live sperm; proMMP-2 with semen volume, % vital sperm, and normal sperm whereas MMP-2 was positively correlated with total count of motile sperm, and normal motile sperm. These findings infer that the role of proMMP-9 and MMP-9 activation may contribute to, at least in part, the cause of poor semen quality. For the reason that MMP-2 activity is intimately associated with high sperm motility, the activation of MMP-2 might improve or be indicators of sperm functionality.