Induction of ornithine decarboxylase and S-adenosylmethionine decarboxylase by sulfobromophthalein in rats

Effect of glutathione modulation of the distribution and transplacental uptake of 2-[14C]-chloroacetonitrile (CAN) quantitative whole-body autoradiographic study in pregnant mice

Chloroacetonitrile (CAN), a drinking water disinfectant by-product, has mutagenic and carcinogenic properties. CAN is known to deplete glutathione (GSH), and previous studies reported an enhanced molecular interaction of CAN after GSH depletion in the uterine and fetal tissues of mice. The present report may help to understand the potential mechanisms involved in such molecular interactions by examining the disposition, transplacental uptake and covalent interaction of the chemical in normal and GSH depleted pregnant mice (at 13th day of gestation). Both normal and GSH depleted (by administration of Diethylmaleate (DEM), 0.6 mL/kg, i.p.) pregnant mice were given an equitoxic i.v. dose of 2-[14C]-CAN(333 microCi/kg equivalent to 77 mg/kg). Animals were processed for whole-body autoradiography (WBA) at 1, 8 and 24 hr after treatment. Tissue distribution of radioactivity in the autoradiographs was quantitated using computer aided image analysis. With few exceptions, a rapid high uptake (at 1 hr) of radioactivity was observed in all major maternal (liver, lung, urinary bladder, gastrointestinal mucosa, cerebellum, uterine luminal fluid) and fetal (liver, brain) organs of both normal and GSH depleted mice. This pattern of distribution was observed, with lesser intensity, at 8 hr following treatment. At a later time period (24 hr), there was a significant higher retention and covalent interaction of radioactivity in GSH depleted mouse tissues especially in the liver as compared to normal mouse. This study suggests that 2-[14C]-CAN and/or its metabolites are capable of crossing the placental barrier. The observed higher uptake and retention of the radioactivity in the maternal liver, kidney, cerebellum, nasal turbinates and fetal liver may pose toxicity of the chemical to these organs. The increased covalent interaction of radioactivty in GSH depleted mice liver may indicate the potential utilization of GSH pathway by this organ in the detoxication of CAN derived metabolites and thus exerting hepatotoxicity.

Effect of L-methionine on 2-carboxybenzaldehyde reductase induction by phenobarbital in primary cultures of rat hepatocytes

Effects of phenobarbital (PB) and L-methionine on 2-carboxybenzaldehyde (CBA) reductase in rat hepatocyte primary culture were examined. Inclusion of PB in the culture medium markedly enhanced the CBA reductase activity while L-methionine, which elevates the cellular glutathione (GSH) level, suppressed the stimulatory effect of PB. This suppression, though less pronounced, was also found with other precursors of GSH biosynthesis. GSH-depletors, buthionine sulfoximine (BSO) or diethylmaleate (DEM), enhanced the CBA reductase activity suggesting that GSH plays an important role in enzyme induction.

Comparative studies of the effects of stilbene compounds on hepatic ornithine decarboxylase and S-adenosylmethionine decarboxylase induction in rats

Trans-Stilbene oxide (TSO, 2 mmol/kg, ip.) induced ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) to 60-fold and 5-fold of the controls, respectively, in the liver of rats. Parallel to ODC induction, there was a marked increase in putrescine content to 50-fold of the control levels. Cis-Stilbene oxide (CSO), a stereoisomer of TSO, also produced the induction of ODC and SAMDC and the increase in putrescine content. There was no difference in the ability to induce ODC and SAMDC between TSO and CSO with respect to the extents of induction and the time needed to reach maximal levels. Trans-Stilbene (TS), a mother compound of TSO, did not show such an effect on ODC, while cis-stilbene (CS) induced both ODC and SAMDC. Treatment with glutathione inhibited TSO- and CSO-mediated induction of ODC and SAMDC. These findings add new information concerning the abilities of TSO, CSO and CS on hepatic polyamine metabolism.