雌性小鼠肝脏中雌二醇可通过雌激素受体降低半胱氨酸磺酸脱羧酶进而降低牛磺酸水平

Cysteine sulfinic acid decarboxylase (CSAD) and cysteine dioxygenase (CDO) are two rate-limiting enzymes in taurine de novo synthesis, and their expressions are associated with estrogen concentration. The present study was designed to determine the relationship between 17(3-estradiol (E2) and taurine in female mice liver. We initially observed the mice had lower levels of CSAD, CDO, and taurine during estrus than diestrus. We then, respectively, treated the ovariectomized mice, the cultured hepato-cytes, and Hep G2 cells with different doses of E2, and the CSAD and CDO expressions and taurine levels were analyzed. The results showed that E2 decreased taurine level in the serum and the cultured cells by inhibiting CSAD and CDO expressions. Furthermore, we identified the molecular receptor types through which E2 plays its role in regulating taurine synthesis, and our results showed that estrogen receptor-a (ERa) expression was much higher than estrogen recep-tor-(3 (ER(3) in the liver and hepatocytes, and the inhibiting effects of E2 on CSAD, CDO, and taurine level were partially abrogated in the ICI-182,780-pretreated liver and hepatocytes, and in ERa knockout mice. These results indicate that estradiol decreases taurine content by reducing taurine biosynthetic enzyme expression in mice liver.