ABSTRACT
Title
Effects of cigarette smoke on human salivary antioxidant defense system
Authors
C. Nencini1, G. Montefrancesco2, L. Micheli1
1 “Giorgio Segre” Pharmacology Section,
2 Centro Studi sulle Dipendenze Patologiche,
Dept. of Neurological, Neurosurgical and Behavioural Sciences, University of Siena
1 “Giorgio Segre” Pharmacology Section,
2 Centro Studi sulle Dipendenze Patologiche,
Dept. of Neurological, Neurosurgical and Behavioural Sciences, University of Siena
Abstract
Cigarette smoke is associated with a variety of human pathologies including cardiovascular diseases and cancer. Oral squamous cell carcinoma is the most common malignancy of the head and neck and the exposure to tobacco is the main inducer of this pathology (1). Recent studies demonstrated that oxidative stress contributes to the development of oral carcinogenesis through DNA damage (2).
It is known that cigarette smoke contains several oxidants and free radicals, and it has been generally assumed that these radicals molecules are involved in the damage to biomolecules and therefore in the pathologies smoking induced.
Saliva has an enzymatic and non enzymatic antioxidant defense system able to counteract toxic activity of radical species and oxidant substances.
The aim of this study was to measure the glutathione peroxidase (GPx), glutathione reductase (GR) (as enzymatic antioxidant defense system) and glutathione oxidized (GSSG), glutathione reduced (GSH) and ascorbic acid (AA) (as non enzymatic antioxidant defense system) in human saliva, for estimating the level of oxidative stress caused by cigarette smoke.
Forty-seven subjects (22 males and 25 females) were enrolled for the study, their mean age was 22.9 (±2.76 years). The participants were 21 smokers (6 males and 15 females) and 26 non-smokers (16 males and 10 females). Furthermore, 6 subjects of the non-smokers group were ex-smokers (3 males and 3 females). All subjects were interviewed and the oral cavity was carefully explored. After rinsing the mouth with water, each subject put 5 ml of non-stimulated saliva inside a test tube.
Saliva was taken at the same time of day to prevent any variations which may be attributable to the circadian rhythm. The samples were frozen at -80°C and later centrifuged and processed according to specific methods for determinations of GPx, GR, GSH, GSSG, and AA.
Independently from the gender or the other variables, a significant decrease of GPx activity (50% about) was detected in the smokers group (p< 0.01) respect to non smokers, while the GR activity was similar in smokers and non-smokers groups;in addition in smokers group the GSH levels were decreased (20% with P<0.05), while GSSG levels were increased (about 15% P<0.05) respect to non-smokers group.
An interesting gender difference is found in GPx activity: the value was lower in male smokers group respect to female smokers (P <0.001), similarly in sample of the male non-smokers respect to female non-smokers (P <0.01). Moreover, there was a significant difference (P< 0.05) in the values of GPx between those who had smoked (ex-smokers) and those who had not smoked never.
Cigarette smoke is a complex chemical system and the generated reactive oxygen species may contribute to oral cancer. We observe that the cigarette smoke decreases the GSH-Px activity interfering with the detoxification of hydrogen peroxide. The overproduction of H2O2 may lead to oxidative stress and this was showed by decrease of glutathione.
Oxidative stress status may lead to large number of diseases, including precancerous and neoplastic lesions of the oral cavity. It is important quit smoking, in fact, as demonstrated, the effects of cigarette smoke on salivary antioxidant enzymes decrease after withdrawal from smoking and the benefits become more evident inthe course of time.
References
It is known that cigarette smoke contains several oxidants and free radicals, and it has been generally assumed that these radicals molecules are involved in the damage to biomolecules and therefore in the pathologies smoking induced.
Saliva has an enzymatic and non enzymatic antioxidant defense system able to counteract toxic activity of radical species and oxidant substances.
The aim of this study was to measure the glutathione peroxidase (GPx), glutathione reductase (GR) (as enzymatic antioxidant defense system) and glutathione oxidized (GSSG), glutathione reduced (GSH) and ascorbic acid (AA) (as non enzymatic antioxidant defense system) in human saliva, for estimating the level of oxidative stress caused by cigarette smoke.
Forty-seven subjects (22 males and 25 females) were enrolled for the study, their mean age was 22.9 (±2.76 years). The participants were 21 smokers (6 males and 15 females) and 26 non-smokers (16 males and 10 females). Furthermore, 6 subjects of the non-smokers group were ex-smokers (3 males and 3 females). All subjects were interviewed and the oral cavity was carefully explored. After rinsing the mouth with water, each subject put 5 ml of non-stimulated saliva inside a test tube.
Saliva was taken at the same time of day to prevent any variations which may be attributable to the circadian rhythm. The samples were frozen at -80°C and later centrifuged and processed according to specific methods for determinations of GPx, GR, GSH, GSSG, and AA.
Independently from the gender or the other variables, a significant decrease of GPx activity (50% about) was detected in the smokers group (p< 0.01) respect to non smokers, while the GR activity was similar in smokers and non-smokers groups;in addition in smokers group the GSH levels were decreased (20% with P<0.05), while GSSG levels were increased (about 15% P<0.05) respect to non-smokers group.
An interesting gender difference is found in GPx activity: the value was lower in male smokers group respect to female smokers (P <0.001), similarly in sample of the male non-smokers respect to female non-smokers (P <0.01). Moreover, there was a significant difference (P< 0.05) in the values of GPx between those who had smoked (ex-smokers) and those who had not smoked never.
Cigarette smoke is a complex chemical system and the generated reactive oxygen species may contribute to oral cancer. We observe that the cigarette smoke decreases the GSH-Px activity interfering with the detoxification of hydrogen peroxide. The overproduction of H2O2 may lead to oxidative stress and this was showed by decrease of glutathione.
Oxidative stress status may lead to large number of diseases, including precancerous and neoplastic lesions of the oral cavity. It is important quit smoking, in fact, as demonstrated, the effects of cigarette smoke on salivary antioxidant enzymes decrease after withdrawal from smoking and the benefits become more evident inthe course of time.
References
- Al-Swiahb JN, Chen CH, Chuang HC, Fang FM, Tasi HT, Chien CY. Clinical, pathological and molecular determinants in squamous cell carcinoma of the oral cavity. Future Oncol. 2010; 6:837-50.
- Lawless MW, O'Byrne KJ, Gray SG. Targeting oxidative stress in cancer. Expert Opin Ther Targets. 2010; 14:1225-45.