Effects of different exposure times to tobacco smoke intoxication on carboxyhemoglobin and hepatic enzymate activities in mice

Smoking is not associated with nonalcoholic fatty liver disease

AIM: To analyze the relationship between smoking and nonalcoholic fatty liver disease (NAFLD).

METHODS: This is a cross-sectional study of a healthy population, carried out in a check-up unit of a university hospital in Mexico City. We enrolled 933 subjects, 368 current smokers (cases) and 565 persons who had never smoked (controls). Demographic, metabolic and biochemical variables were measured in the two groups. NAFLD was determined by ultrasound and metabolic syndrome according to ATPIII.

RESULTS: A total of 548 men (205 cases and 343 controls) and 337 women (114 cases and 223 controls) were included in the analysis. Statistical differences between cases and controls were observed only in high blood pressure prevalence (6.6% vs 11.3%, P < 0.05; cases and controls respectively), high-density lipoproteins (1.00 ± 0.26 vs 1.06 ± 0.28 mmol/L, P < 0.005), triglycerides (2.18 ± 1.49 vs 1.84 ± 1.1 mmol/L, P < 0.001), and erythrocyte sedimentation rate (11.3 ± 9.3 vs 13.5 ± 11.9 mm/h, P < 0.001). No differences were observed in the prevalence of NAFLD (22.27% vs 29.68%, P = NS) and metabolic syndrome (41.69% vs 36.74%, P = NS). Univariate analysis showed that smoking was not a risk factor for NAFLD (OR = 0.89, 95% CI 0.65-1.21).

CONCLUSION: No differences in NAFLD prevalence were observed between current smokers and nonsmokers, and furthermore, no differences were observed in heavy smokers (more than 20 packs/year), indicating that there is no relationship between smoking and NAFLD.

Exposing ferrets to cigarette smoke and a pharmacological dose of beta-carotene supplementation enhance in vitro retinoic acid catabolism in lungs via induction of cytochrome P450 enzymes

In our previous studies, we found lower levels of retinoic acid (RA) in the lungs of ferrets exposed to cigarette smoke and/or a pharmacological dose of beta-carotene. To determine whether this is involved in excessive catabolism of RA via cytochrome P450 (CYP) induction, we carried out in vitro incubations of RA with the lung microsomal fractions of ferrets with or without CYP inhibitors and antibodies against CYP. The polar metabolites (4-oxo-RA and 18-hydroxy-RA) of RA metabolism after the incubation were analyzed by HPLC. Expressions of CYP (1A1, 1A2, 2E1 and 3A1) were examined using Western blot analysis. Incubation of various concentrations of RA with the lung microsomal fraction from ferrets exposed to cigarette smoke, a pharmacological dose of beta-carotene or their combination dose-dependently increased the levels of 4-oxo-RA and 18-hydroxy-RA compared with that of the control ferrets. At all RA concentrations, this increase was the greatest in lung tissue from the combined treatment group. Furthermore, this enhanced RA catabolism was substantially (approximately 80%) inhibited by nonspecific CYP inhibitors (disulfiram and liarozole), but was partially (approximately 50%) inhibited by resveratrol (CYP1A1 inhibitor), alpha-naphthoflavone (CYP1A2 inhibitor) and antibodies against CYP1A1 and CYP1A2. Cigarette smoke exposure and/or pharmacological doses of beta-carotene increased levels of CYP1A1 and 1A2 by three- to sixfold but not levels of 2E1 and 3A1 in ferret lung tissue. These findings suggest that low levels of RA in the lung of ferrets exposed to cigarette smoke and/or pharmacological doses of beta-carotene may be caused by the enhanced RA catabolism via induction of CYP, CYP1A1 and CYP1A2 in particular, which provides a possible explanation for enhanced lung carcinogenesis seen with pharmacological doses of beta-carotene supplementation in cigarette smokers.

Tobacco smoke influence on heart rate, body temperature, and locomotor activity daily rhythms as assessed by radiotelemetry in rats

Using radiotelemetry, this study aimed to evaluate the influence of tobacco smoke on heart rate (H), body temperature (T) and locomotor activity (A) daily rhythms in rats. The tobacco smoke intoxication was produced with a smoking apparatus. H, T, and A data were captured by radiotelemetry. The study was divided into three periods: a 1-week control period (P1), a 1-week stress period (P2), in order to evaluate the stress induced by the animals' restraint in the smoking apparatus, and a 1-week daily tobacco smoke intoxication period (P3). For P1, P2, and P3, a power spectrum analysis was applied in order to determine the dominant period of rhythmicity. Then, characteristics of the rhythms were determined by cosinor analysis. Statistical comparisons were done by ANOVA. Power spectrum analysis showed that neither stress nor tobacco suppressed the daily rhythmicity. Cosinor revealed some modifications: H amplitude was decreased during P2 and P3 with a greater reduction during P3, while T and A amplitudes were decreased during P2 and P3 without difference between P2 and P3. T acrophase was delayed during P2, while A acrophase was delayed during P2 and P3 without any difference between P2 and P3. These perturbations may reflect the effects of stress and tobacco on the suprachiasmatic nucleus by a dopaminergic mechanism.