the liver enzyme system is linked to the metabolism of toxins and drugs.
what enzyme system is linked to the metabolism of toxins and drugs?
liver
female specific defenses: compared to men, women metabolize toxins at faster rates and detect the presence of toxins at lower concentrations. ovarian hormones have been implicated in the activity of xenobiotic metabolism. research on pregnant women has documented the differential effects of estrogen and progesterone on the expression of cyps in response to cigarette smoke. using hepatic cells, choi et al., (2012) found that progesterone and estradiol altered drug metabolism but only when hormone concentrations reach that which is normal for pregnancy. changes in xenobiotic metabolism in women using birth control also suggest hormonally mediated influences. specifically, changes in hepatic drug elimination for cyp1a2, cyp2c19 and cyp2a6 are similar in pregnant women and non-pregnant women using hormonal contraception. furthermore, in women across the menstrual cycle, smoking topography variables (e.g. total number of cigarettes smoked, mean puff volume, etc.) seem to be mediated by estradiol and progesterone. in various studies, regular smokers have been shown to produce approximately one-third less estrogens (including estradiol) during the postovulatory menstrual phase than non-smoking counterparts. research suggests the reason for this relationship is due to a functional tradeoff, with the enzymes that metabolize estradiol instead metabolizing/detoxifying tobacco toxins.
evolutionary models of human drug use
in addition to the discovery of the enzyme system, bernheim observed several unique properties of the tyramine oxidase system. she noted that the methylene blue dye used in the experiment was not reduced. this observation indicated that the tyramine oxidase system, unlike other enzyme systems, was not able to use the dye as a hydrogen acceptor. additionally, the oxidative process within this enzyme system was seen to be resistant to the addition of cyanide. this observation showed that the tyramine oxidase system was an exception to warburg's statement, which claimed that direct oxidation could not occur unless atmospheric oxygen was activated by iron. instead, the system was seen to produce hydrogen peroxide, indicating that molecular oxygen acted as a hydrogen acceptor in the system. bernheim also detected that the enzyme facilitated the occurrence of deamination in tyramine, along with the process of oxidation.
mary bernheim