| Polycyclic Aromatic Hydrocarbons (PAHs) are a large class of ubiquitous contaminants in the environment. Because of its carcinogenic potential, PAHs have grasped much attention of countries in the world. Naphthalene, the simplest and the most soluble PAH, is commonly used as a model for studying PAHs.Naphthalene is the best studied of the low molecular weight aromatic hydrocarbons both in terms of human exposure and in terms of health effects. It can be found environmentally as a constituent of coal tar, crude oil, and cigarette smoke. It is also used in the production of plasticizers, resins, insecticides, and surface-active agents. Because of its widespread human exposure, its toxic properties have been the subject of numerous assessments.It has been demonstrated that naphthalene exposure resulted in elevated levels of serum and liver lipid peroxides, and decreased hepatic selenium dependent glutathione eperoxidase activity. Naphthalene exposure is also associated with the development of hemolytic anemia in humans and rats. In addition, naphthalene has been shown to induce oxidative stress as evidenced by hepatic and brain lipid peroxidation, GSH depletion, DNA single strand breaks and membrane microviscosity, and excretion of urinary lipid metabolites in rats. At present, the toxicity mechanism of naphthalene has not been elucidated especially at the molecular lever. To clarify Systematically the multiple toxic effects of Naphthalene on living organisms is one of the purposes of this article.Detoxification of naphthalene exposed to the organisms has been in progress and it is a hot spot to develop an effective antidote in vivo currently. Deuterohaemin- AlaHisThrValGluLys (DhHP-6, D) is a peroxidase mimics developed by the Biological Macromolecules Laboratory of Jilin University. Studies have shown that DhHP-6 has anti-oxidative stress caused by paraquat and has the ability of removing free radicals in vitro. The second purpose of this article is to research on the detoxification effect of DhHP-6 in vivo for the Caenorhabditis elegans (C.elegans) exposed to naphthalene.In the present investigation, C.elegans was taken as a good animal model to evaluate the toxicity of naphthalene and the detoxification effects of Deuterohaemin-AlaHisThrValGluLys (DhHP-6, D). C. elegans is a popular model for studying on Environmental Toxicology due to its simple incubation and short lifespan and the well defined genetic analyses. Moreover, C. elegans was the first organisms obtained complete genome sequence and was proven to facilitate people to study the molecular mechanisms. C. elegans was administered with naphthalene (0.3 mg/L, 3 mg/L and 30 mg/L respectively) for 24 hours, along with DhHP-6 (100μM). At the end of experiment, reproduce, life span and locomotion behaviors of the C. elegans were determined as physiological indicators. Free Radicals content in vivo and cell apoptosis were determined as biochemical indicators. Eight genes of hsp16.1, ctl-2, sod-3, cep-1, cyp35a2, gst-1, ugt-44 and dhs-28 were determined as molecular indicators.The experiments showed that the reproduce, life span, locomotion behaviors and Free Radicals content in vivo were all decreased exposed to three concentrations of naphthalene, and they were consistent with the dose - effect relationship. Apoptosis of the C. elegans was increased significantly at 0.3 mg/L and 3 mg/L of naphthalene exposure, while it was declined at 30 mg/L of naphthalene exposure. As for the genes, expression of hsp16.1,ctl-2, sod-3 and cep-1 was increased significantly, while expression of cyp35a2, gst-1, ugt-44 and dhs-28 was minor change. On the other hand, DhHP-6 treatment reversed all these physiological, biochemical and molecular indicators induced by naphthalene.From the results of life spans, the Content of free radicals and the Oxidative stress-related gene (hsp16.1, ctl-2, sod-3, cep-1), we conclude that oxidative mechanisms play an important role in naphthalene-induced the damage of C. elegans, and DhHP-6, by balancing oxidant- antioxidant status, improves oxidative injury due to naphthalene toxicity. |
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