FT-IR and ESR were used for on the investigation of the CCl4-induced peroxidation of rat liver microsomes in combination with biochemical methods. Lipid peroxidation was assayed by TBA reagent in the presence of CCl4 and NADPH. The CCl3 - radical was detected by ESR spectroscopy with a spin trapping reagent of PBN. The FT-IR spectroscopy revealed that absorption band of -C-H in -C=C-H decreased in intensity at 3012 cm(-1), but the absorption bands of the phosphate head and choline in the phospholipids did not significantly change between 1300 and 900 cm(-1). These findings were interpreted to be due to the removal of H- from -C=C-H by radicals as the first step of lipid peroxidation, and to the absence of dephosphorylation of phospholipids in the microsomal membrane. This is the first IR spectroscopic evidence indicating the nature of damage to a microsomal membrane caused by CCl4 treatment. The spectroscopies used here demonstrated that they are useful tools to observe the damage

The LEC rat is reported to exhibit hypersensitivity to X-irradiation, deficiency in DNA double-strand break repair, and radio-resistant DNA synthesis. This character of the LEC rat has been thought to be due to abnormal G1 arrest in cells after X-irradiation. In this report, we re-investigated the effect of X-irradiation on the cell cycle in primary-cultured fibroblasts. Primary-cultured fibroblasts derived from LEC and BN rats were exposed to 4 Gy of X-ray and their cell cycle analysis was performed with a flow cytometer. Fibroblasts derived from both rats showed normal response of the cell cycle, indicating the arrest at both G1- and G2/M-phase and no difference in the cell cycle population between fibroblasts derived from both rats. In contrast, when the same analysis was performed using the cell line, L7 and W8, which had been established from the lung fibroblasts of LEC and control WKAH rats, respectively, by immortalizing with SV40 T-antigen, L7 cells but not W8 cells showed impaired G1 arrest and abnormal cell cycle. These results suggest that fibroblasts derived from LEC rats possess the normal cell cycle response after X-irradiation, if they are kept naive as not immortalized with SV40 T-antigen.

Green tea contains catechins and caffeine as major constituents. Treatment of rats with green tea (2.5% w/v) significantly increased 7-ethoxycou-marin 0-deethylase (7-ECOD), caffeine N-1 demethylase (CN1D) and UDP-glucuronyltransferase (UGT) activities. Treatment with caffeine similarly activated CYP1A2 and related monooxygenases as well as UGT, while treatment with catechins induced UGT activity but not 7- ECOD or CN1D activity. Numbers of benzo[a]pyrene (BP) -induced revertant colonies in an Ames test (mutation assay) with S. typhimurium TA98 as the test strain were markedly larger when BP was preincubated with the liver S-9 (9000 x g supernatant of liver homogenate) from green tea-treated rats than when preincubated with that from control rats. In a modified Ames assay system in which UGT was activated by the addition of UDP-glucuronic acid to the preincubation mixture, numbers of revertant colonies in the assay using liver S-9 from green tea-treated rats decreased to a similar level to that in the assay using S-9 from controls. The acceleration of two enzymatic reactions may contribute to the rapid elimination of BP; the first step, the formation of a metabolic intermediate (which is mutagenic) by CYP1A2 and the second, the conjugation of active metabolic intermediates by UGT. We speculated that green tea can reduce the amount of time carcinogens reside in the body and the chance that body tis-sues will be exposed to active metabolites of carcinogens thorough rapid elimination due to the simultaneous induction of CYP1A2 and UGT activities.

Interleukin (IL)-6, a cytokine for host defense responses to infection and imflammation, is known to be induced by non-invasive physical or psychological stress, too. To test possible involvement of brain IL-1 in the stress-induced IL-6 production, IL-1 mRNA expression in the hypothalamus, in parallel with blood IL-6 Ievel, was examined in rats subjected to restriction of their movement (immobilization stress). When rats were immobilized, the hypothalamic IL-1 beta mRNA Ievel was increased in 1 hr, followed by progressive rises in the serum IL-6 level. The immobilization-induced rise in serum IL-6 was mimicked by intracerebroventricular (icv) administration of IL-1 beta under normal conditions, whereas it was attenuated by icv injection of an IL-1 receptor antagonist. These results indicate that IL-1 in the hypothalamus plays a pivotal mediating role in the stress-induced peripheral IL-6 production.

We have investigated the accumulation of diacylglycerol (DAG) induced by carbon tetrachloride (CCl4)-derived radicals in the liver of female Sprague-Dawley (SD) rats after intraperitoneally injecting CCl4. DAG is an intracellular activator of protein kinase C (PKC) which regulates cell proliferation and differentiation. The electron spin resonance (ESR) study gave the signal of the PBN-CCl3 adduct in the liver of the rats which were pretreated with PBN, confirming that CCl4 was metabolized into CCl3-radicals with cytochrome P450 enzyme and indicating that PBN could trap them. The blood biochemical assay supported the trapping of the CCl3-radicals; the pretreatment of rats with PBN inhibited the increase in the GOT and GPT values upon exposure to CCl4. The Fourier transform-infrared (FT-IR) study indicated in comparison with the model compounds that the CCl4-injected rats accumulated DAG in addition to phosphatidylcholine, phosphatidylethanolamine and triglyceride (TG) in the lipid membrane fraction of the liver homogenate. DAG was found to be ca. 10-15% of the membrane phospholipids by weight. However, DAG was not found in the lipid of the liver microsomes, suggesting that it is formed only in the cell membrane of liver. Also, neither DAG nor TG was found in the lipid membrane of the rats that were pretreated with PBN followed by an injection of CCl4. The formation of DAG was confirmed by an HPLC study. The activation of PKC was observed in liver homogenate in the rats that were injected with CCl4. On the basis of the above findings, it was concluded that the CCl4-derived radicals stimulate PKC through the accumulation of DAG in the liver membrane of the rats. Furthermore, it was shown that PBN has a protective and therapeutic effect against CCl4-induced damage