![]() The results showed that testosterone secretion was obviously decreased after the inhibition of CSD mRNA expression in cultured Leydig cells. Meanwhile, the effect of silencing CSD mRNA by siRNA on testosterone secretion was analyzed. Testosterone secretion induced by progesterone was significantly stimulated by treating with 1.0 and 10 microg/ml of taurine, however, it was significantly inhibited when treated with 400 microg/ml of taurine. Testosterone secretion stimulated by HCG was significantly increased by 10 and 100 microg/ml of taurine administration, and obviously decreased by treating with 400 microg/ml of taurine. Low concentrations of taurine (0.1-100 microg/ml) could stimulate testosterone secretion, whereas high concentration of taurine (400 microg/ml) could inhibit testosterone secretion. The results showed that taurine had biphasic effects on basal testosterone secretion in cultured Leydig cells. ![]() In vitro, cultured Leydig cells were treated with taurine independently or incubated with human chorionic gonadotropin (HCG) and progesterone. Taurine administered in water could significantly increase the concentration of taurine in the blood and testis of rats. The results showed that taurine obviously stimulated the secretion of FSH, LH and testosterone in serum, but showed no significant effect on the secretion of estradiol. In vivo, taurine were administered to male rats by tap water. At the same time, the effects of taurine on testosterone secretion were investigated both in vivo and in vitro. The results showed that CSD mRNA was expressed in rat testis, and the putative encoded-amino acid sequence was exactly the same as that in rat liver which was already known. Clearly, the role of taurine in the physiology of the water insoluble vitamins remains an enigma and is worthy of further investigations.In the present study, the cysteine sulfinate decarboxylase (CSD) mRNA expression was detected in rat testis by RT-PCR. This form of delivery may be an additional, secondary mechanism for the transport of lipid soluble vitamins, which was probably acquired early in evolution, and remains extremely important for mammals and humans directly after birth for a variety of physiological functions such as: vision in normal and in emergency situations, rapid blood clotting, sperm eruption, and situations requiring a prompt consumption of lipid soluble vitamins characteristic of excitable systems. It is quite possible that the ability of taurine to convert lipids and lipid soluble substances into a water soluble state is the key to understanding the unusually wide diversity of biological phenomena associated with taurine. On the basis of recent finding concerning the relationship between taurine and the aldehyde of vitamin A-retinal (Petrosian and Haroutounian, 1988, 1998 Petrosian et al., 1996), as well as on the basis of data from the literature, we now suggest a hypothesis that taurine promotes the bioavailability of the lipid soluble vitamins A, D, E, K, and F, probably by forming different types of water soluble, easily hydrolyzable complexes. In the literature taurine is characterized as a non-specific growth or blood clotting factor, an antioxidant, a membrane protector, or a regulator of calcium ion homeostasis, just as vitamins A, D, E, F, and K are similarly characterized. ![]()
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