Steinetz B G, Schwabe C, Callard I P, Goldsmith L T
Department of Environmental Medicine, New York University Medical Center, Tuxedo 10987, USA.
J Androl. 1998 Jan-Feb;19(1):110-5.
Relaxin is a 6-kd polypeptide that exerts important hormonal effects in many female mammals. Relaxin is produced by the ovary, placenta, or uterus in many mammalian species. The functions of relaxin in the male mammal are not yet firmly established, but there is some evidence suggesting an exocrine effect on sperm motility and fertilizability. In the male mammals that have been studied, relaxin is produced by the prostate gland (human) or seminal vesicles (boar). However, in the bird, the testis is the likely source of relaxin. Among the elasmobranchs, ovaries obtained from dogfish sharks have been shown to contain a polypeptide hormone that is structurally, biologically, and immunologically similar to mammalian relaxins, but the male reproductive tract of this species has not previously been investigated as a potential source of relaxin. Extracts of testes obtained from mature dogfish sharks have now been tested by a specific relaxin bioassay and by a homologous porcine radioimmunoassay for the presence of relaxin. Both crude and partially purified testicular extracts contained unmistakable guinea pig pubic symphysis-"relaxing" activity and relaxin-like immunoactivity. Following immunoaffinity purification, the shark testis polypeptide had an apparent specific activity of 88 microg porcine relaxin equivalents per milligram in the radioimmunoassay, which is similar to the immunoactivity of pure shark ovarian hormones. These data, therefore, strongly support the view that in dogfish sharks, the male as well as the female gonad produces relaxin. Furthermore, as the dogfish shark has existed as a species for about 200 million years, the data suggest that testicular relaxin appeared early in vertebrate evolution.
松弛素是一种6千道尔顿的多肽，在许多雌性哺乳动物中发挥重要的激素作用。在许多哺乳动物物种中，卵巢、胎盘或子宫会产生松弛素。松弛素在雄性哺乳动物中的功能尚未完全明确，但有证据表明它对精子活力和受精能力有外分泌作用。在已研究的雄性哺乳动物中，松弛素由前列腺（人类）或精囊（野猪）产生。然而，在鸟类中，睾丸可能是松弛素的来源。在软骨鱼类中，已证明从角鲨获取的卵巢含有一种多肽激素，其在结构、生物学和免疫学上与哺乳动物的松弛素相似，但此前尚未对该物种的雄性生殖道作为松弛素的潜在来源进行研究。现在，通过特定的松弛素生物测定法和同源猪放射免疫测定法，对从成熟角鲨获取的睾丸提取物进行了松弛素检测。粗提物和部分纯化的睾丸提取物都含有明显的豚鼠耻骨联合“松弛”活性和松弛素样免疫活性。经过免疫亲和纯化后，角鲨睾丸多肽在放射免疫测定中的表观比活性为每毫克88微克猪松弛素当量，这与纯鲨鱼卵巢激素的免疫活性相似。因此，这些数据有力地支持了这样一种观点，即在角鲨中，雄性和雌性性腺都会产生松弛素。此外，由于角鲨作为一个物种已经存在了约2亿年，这些数据表明睾丸松弛素在脊椎动物进化早期就已出现。
