TY  - THES
T1  - Effects of polycyclic aromatic hydrocarbons in developing chicks with emphasis on immunotoxicity
A1  - Ravindran, Nisha Aynikkattil
LA  - English
YR  - 2016
UL  - http://discoverylib.upm.edu.my/discovery/Record/oai:ethesis.upm.edu.my:12753
AB  - Polycyclic aromatic hydrocarbons (PAHs) are persistent pollutants and chemically a class of structurally similar chemical compounds characterised by the presence of
fused aromatic rings. Only a few studies have addressed problems concerning the health impact of PAHs in avian species over the years. This research was undertaken
to find out the immunotoxic effects produced by pyrene, phenanthrene and fluoranthene. These chemicals were injected into developing chicks at 3 dose levels
(0.2, 2 and 20mg per kg) along with control and vehicle alone groups ,to rule out possible mechanisms involved in immunotoxicity. A minimum number of six chicks were taken for each parameter.The study has 4 main objectives: To find out if there is any changes in hatchability index, organ weights and toxic morphological changes in immune tissues of chicken embryos by pyrene, fluoranthene and phenanthrene; To analyse the correlation with aryl hydrocarbon receptor (AHR) activation and
immunotoxicity by PAHs; To identify DNA damage produced by PAHs in immune organs by analysing DNA adducts and DNA breaks and to analyse the effect on immunoglobulins and cytokines by PAHs. Hatchability index and organ somatic indices were calculated and histopathology of bursa of fabricius, spleen and thymus was performed. Hatchability showed a drastic reduction at 20mg/kg of all three compounds. Thymus was the only organ affected with reduced organ somatic index whereas indices of spleen and bursa of fabricius remain unchanged. The histopathological lesions in thymus, bursa of fabricius and spleen indicated that all the three compounds led to immunotoxic lesions at 20 mg per kg. A 650 base pair product was observed by RNA extraction and reverse transcription PCR from the thymus, bursa of fabricius and spleen. Quantitative estimation of AHR indicated an increased concentration at 0.2, 2 and 20 mg per kg dose levels of all three compounds in the bursa of fabricius and thymus. After DNA extraction, DNA adducts were analysed by DNA adduct ELISA kit to rule out DNA damage. A significant increase in the DNA adduct levels was found in thymus and bursa in 2mg and 20mg dose levels of pyrene, fluoranthene and phenanthrene treated groups, whereas spleen levels simulated the value of controls. Immunoglobulins and cytokines in serum were assessed by ELISA technique. Pyrene, phenanthrene and fluoranthene did not affect immunoglobulins. T lymphocyte activating cytokines was markedly reduced by these PAHs. Pyrene, phenanthrene and fluoranthene did not affect immunoglobulins. RBC count and WBC counts showed reduction and heterophil to lymphocyte ratio showed
an increase indicating impairment of lymphopoiesis. It can be concluded that pyrene, fluoranthene and phenanthrene are immunotoxic in developing chicks at 2 and 20 mg per kg dose levels and it might be mediated through aryl hydrocarbon receptor as indicated by their up regulation.
ER  -