Studies On The Mechanism Of Cadmium-Induced Apoptosis In Chicken Splenic Lymphocytes

Cadmium was one of toxic metal elements, which was ubiquitous in environment. As an important environmental pollution material, cadmium has endangered human and animals' health, it caused universal research and emphasis. Foreign researchers have studied the effects of cadmium on seagull, widgeon, penguin and sparrow, which mainly concentrated on accumulation and damage of cadmium in the organ of liver and kidney in vivo of birds, while little research about immunotoxicty has been reported. In this paper chicken splenic lymphocytes cultured in vitro was used as experiment materials, treated with 10μmol/L CdCl2. in order to study the mechanism of cadmium-induced apoptosis in chicken splenic lymphocytes, some items about the activity of cell, apoptosis, antioxide function, DNA damage and the expression level of Bcl-2 and p53 mRNA in chicken splenic lymphocytes were detected. The results showed as follows:It was the first time to detect the IC50 of cadmium on chicken splenic lymphocytes by the trypan blue method and MTT assay respectively. The results of 17.09±0.63μmol/L of 24h, 13.03±0.62μmol/L of 48h and 10.15±0.36μmol/L of 72h demonstrated that immunocyte of avian is supersensitive to cadmium, and the sensitivity increases along with times going.Flow cytometry assay and AO/EB double fluorescence coloration was used respectively to detect apoptosis induced by cadmium in chicken splenic lymphocytes from the aspects of biochemical change and morphological change. It revealed that cadmium exhibited immunotoxicity by the way of induction apoptosis of avian immunocyte.From the detection of the contents of NO and MDA, and the activity of NOS, SOD and GSH-Px, this study demonstrated that cadmium caused oxidative stress in chicken splenic lymphocytes, apoptosis, so as to exhibit immunotoxicity to avian immunocell.The effects of cadmium on DNA damage in chicken splenic lymphocytes were detected through different aspects by the method of alkaline SCGE, quantitative analysis of DNA fragmentation and DNA ladder analysis. The results showed that cadmium caused DNA damage of lymphocytes, which exhibited time-dependent effect. It revealed that the effects of cadmium on DNA damage may be one of important mechanisms of avian immunotoxicity on cadmium and also may be an important factor of apoptosis. The optimal conditions of semi-quantitive RT-PCR for detecting the expression level of Bcl-2 and p53 mRNA in chicken splenic lymphocytes was investigated, and it was the first time to use this method to detect the effects of cadmium on the expression level of Bcl-2 and p53 mRNA in chicken splenic lymphocytes. It demonstrate that cadmium interfered with the expression of Bcl-2 and p53 mRNA in avian immunocyte, furthermore, cadmium induced apoptosis.This research elucidated the mechanism of cadmium on immunotoxicity in avian. On the molecular level from the aspects of cell toxicity, apoptosis, oxidative stress, DNA damage and the expression of oncogenes. The mechanism would play an important role in wild animal resource protection, ecology balance maintenance, prevention and therapy in domestic poultry toxicity and promotion of animal husbandry industry.Postgraduate: Li JinlongSpeciality: Clinical Veterinary ScienceSupervisor: Vice-Prof.Xu Shiwen...