Biochemical and histopathological studies of posible co-morbidity of cadmium, chromium and lead in albino rats
Date
2023-09
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Publisher
Federal University of Technology, Owerri
Abstract
Cadmium, chromium and lead are known environmental pollutants that induce toxicity in living organisms when exposed to them. The risk assessment of Cd, Cr and Pb is done individually while in reality living organisms are exposed to them jointly as they co-occur in the environment, food or water. This study was aimed at investigating their possible co-morbidity through biochemical and histopathological evaluations of albino rats exposed to them simultaneously. Seventy male albino rats were used in the study. Specified doses of 5, 10, and 20mg/kg body weight respectively, of these pollutants/metals were administered by gavage thrice weekly to 60 albino rats and 10 albino rats were used as control. There were four treatment groups Cd, Cr, Pb and Cd+Cr+Pb (i.e. Cd alone, Cr alone, Pb alone and Cd, Cr, Pb combined) per dose with five animals per treatment group. The treatments were for 90 days, and salt solutions of the metals (i.e. CdSO4, K2Cr2O7, and Pb(NO3)2) were used while the control received only distilled water. Body weights (BW) of the rats were measured and percentage BW gains of the rats were calculated. The animals were sacrificed after 90 days and blood samples were analyzed for alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH),
total bilirubin, urea, creatinine, potassium (K), chloride (Cl), inorganic phosphorus, malondialdehyde (MDA), reduced glutathione (GSH), ascorbic acid, superoxide dismutase (SOD), catalase (CAT), haemoglobin (Hb), packed cell volume (PCV), white blood cell (total) (WBC[T]), and red blood cell (RBC). Organ (liver, kidney, & heart) to BW ratio were measured. Histopathological evaluations of liver, kidney, and heart were done. Results of combined treatment showed hormetic response with regard to ALT, AST, total bilirubin, and urea as they were elevated in the low dose but decreased with high dose. This phenomenon was also observed in Cr individual treatment except in total bilirubin. The results showed that ALP, LDH, K, and inorganic phosphorus levels in the combined treatment group increased with increasing dose but was not significantly different (p>0.05) from that of the most hazardous metal in the individual treatments. Oxidative stress was observed in both the combined and individual treatments as MDA increased while GSH and ascorbic acid were reduced with increasing dose. SOD and CAT increased with increasing dose hence reducing the impact of the oxidative stress as observed. Less-than-additive interaction was observed in the 5mg/kg treatment group among the mixture components with regard to Hb and WBC. Combined treatment with the metals caused significant decrease in percentage BW gain but was not significantly different (p>0.05) from that of the
most hazardous metal in the individual treatments. Histopathological evaluation showed tissue injury in liver and kidney in the 20mg/kg combined and individual treatment groups only probably due to high dose. Mortality was observed in the course of the study as two animals died due to the combined treatment (i.e. one at 10mg/kg group and one at 20mg/kg group) while three animals died due to the individual treatments (i.e. one at 10mg/kg Cd group, one at 20mg/kg Cr group and one at 20mg/kg Pb group). Conclusively, the results suggested that there was no significant health risk posed by
simultaneous exposure to the metals beyond the risk already posed by the most hazardous individual metal for the endpoint of interest. Interactions where they occurred were predominantly less-than additive. Hormesis should be considered in their risk assessment. The concept of effect addition
(independent action) over-estimated the risk due to the combined treatments.
Description
A Doctoral thesis on albino rats. it contains diagrams, mathematical equations, tables and graphs
Keywords
hormetic, combined, histopathological, hazardous, individual, interaction, Department of Biochemistry, treatment
Citation
Osoh, K. (2023). Biochemical and histopathological studies of posible co-morbidity of cadmium, chromium and lead in albino rats. ( Unpublished Doctoral Thesis ). Federal University of Technology, Owerri