Transplantation of fetal liver tissue suspension into the spleens of adult syngenic rats: effects of different cytotoxins on cytochrome P450 mediated monooxygenase functions and on oxidative state

Summary Syngenic fetal liver tissue suspensions were transplanted into the spleens of adult male Fisher 344 inbred rats. Four months after surgery, transplant recipients and age matched control rats were treated with different cytotoxins (allyl alcohol AAL, bromobenzene BBZ, carbon tetrachloride CCl 4 , or thioacetamide TAA) or the respective solvents 24 or 48 hours before sacrifice. Effects of the cytotoxins on P450 mediated monooxygenase functions in liver and spleen 9,000g supernatants were assessed by measuring the model reactions ethoxyresorufin O-deethylation (EROD), ethoxycoumarin O-deethylation (ECOD), pentoxyresorufin O-depentylation (PROD), and ethylmorphine N-demethylation (EMND). Additionally, the influence on the oxidative state was investigated by assessing the liver and spleen tissue content of lipid peroxidation (LPO) products and of reduced and oxidized glutathione (GSH; GSSG). The livers of both solvent treated transplant recipients and control rats displayed regular EROD, ECOD, PROD and EMND activities. After AAL treatment EROD and EMND activities within the livers were not affected, but ECOD and PROD activities were increased. BBZ administration caused a decrease in EROD and EMND activities, ECOD activity remained unaffected, and PROD activity was even increased. CCl 4 and TAA administration caused a strong reduction in the activity of all four model reactions. Spleens of control rats displayed almost no P450 mediated monooxygenase functions, independent whether the rats had been treated with the cytotoxins or not. In the transplant containing spleens, however, significant EROD and ECOD, but hardly any PROD or EMND activities were seen. After AAL administration EROD activity was not affected in the transplant containing spleens, but ECOD activity was increased. BBZ treatment led to a decrease in EROD and an elevation in ECOD activity. CCl 4 and TAA strongly reduced the activity of both of these model reactions. The tissue content of LPO products within livers and transplant containing spleens was significantly increased after BBZ and CCl 4 treatment. An elevation in LPO products was also seen in the spleens of the control rats due to CCl 4 administration. Tissue GSH and GSSG content in both livers and transplant containing spleens were strongly reduced after BBZ treatment. After CCI4 administration only a significant decrease in liver GSSG contents was seen. TAA treatment caused a reduction in the GSH and GSSG content in the spleens of both transplant recipients and control rats, but not in the livers. From these results it can be concluded, that the effects of cytotoxins like AAL, BBZ, CCl 4 or TAA onP450 dependent monooxygenase functions and on oxidative state are exerted in the ectopic intrasplenic liver cell transplants in a similar way as in normal orthotopic liver.