Muftau Shittu

Ameliorative effects of vitamin C on short-term sensorimotor and cognitive changes induced by acute chlorpyrifos exposure in Wistar rats

Human and experimental animal studies have shown long- and short-term neurological sequelae following acute organophosphate (OP) exposure. Although the main molecular mechanism of OP neurotoxiicty involves acetylcholinesterase (AChE) inhibition, studies have also implicated the induction of oxidative stress. The present study was therefore aimed at evaluating the effect of acute chlorpyrifos (CPF) exposure on short-term sensorimotor and cognitive changes in Wistar rats, the role of brain lipoperoxidative changes and the effect of pretreatment with vitamin C. Twenty-eight rats divided into four groups of seven rats in each group served as subjects for this study. Rats in group I were given soya oil (2 ml/kg) while those in group II were dosed vitamin C (100 mg/kg). Group III were administered CPF only (42.5 mg/kg ∼50% of LD50), while group IV were pretreated with vitamin C (100 mg/kg) and then exposed to CPF (42.5 mg/kg), 30 min later. The regimens were administered once orally and the animals were examined for clinical signs, death and subjected to periodic neurobehavioral evaluation for motor strength, coordinated gait, neuromuscular coordination, learning and memory. At the end of 8 weeks of evaluation, the rats were sacrificed and the brain tissue evaluated for AChE activity and malonaldehyde (MDA) concentration, as an index of lipoperoxidative changes. The rats administered with CPF showed deficits in motor strength, coordinated gaits, neuromuscular coordination, learning and memory, slight decrease in AChE activity and an increase in brain MDA concentration. Pretreatment with vitamin C improved the neurobehavioral deficits and AChE activity, and caused a significant reduction in MDA concentration. In conclusion, the study has demonstrated that acute CPF exposure in Wistar rats caused short-term impairment in sensorimotor and cognitive functions partly due to brain lipoperoxidative changes, which were ameliorated by pretreatment with vitamin C.

Ameliorative effect of vitamin C on alterations in thyroid hormones concentrations induced by subchronic coadministration of chlorpyrifos and lead in wistar rats.

The present study evaluated the ameliorative effect of vitamin C on alteration in thyroid hormones induced by low-dose subchronic coadministration of chlorpyrifos (CPF) and lead (Pb). Forty Wistar rats were divided into 4 groups of 10 animals each. Groups I and II were administered soya oil (2 mL/kg) and vitamin C (100 mg/kg), respectively. Group III was coadministered CPF (4.25 mg/kg ~1/20th LD50) and Pb (250 mg/kg ~1/20th LD50), respectively. Group IV was pretreated with vitamin C (100 mg/kg) and then coadministered with CPF (4.25 mg/kg) and Pb (250 mg/kg), 30 min later. The regimens were administered by gavage for a period of 9 weeks. The marginal decrease in serum triiodothyronine and thyroxine and the significant increase in the concentrations of thyroid stimulating hormone and malonaldehyde in the group coadministered with CPF and Pb were ameliorated by vitamin C partly due to its antioxidant properties.

Effects of Administration of Carbamazepine and/or Phenytoin on Serum Biochemical Parameters in Wistar Rats.

This study was conducted to evaluate the serum biochemical alterations following the administration of carbamazepine (CBZ) and/or phenytoin (PHE) in Wistar rats. Forty male adult Wistar rats weighing between 144 and 300 g were used for the experiment. They were divided into four (4) groups of 10 animals each. Rats in groups II, III and IV were given CBZ (20 mg/kg), PHE (100 mg/kg) and CBZ+PHE (20 and 100 mg/kg separately), respectively. Rats in group I were given distilled water at 2 ml/kg and served as untreated control. All treatments were administered orally by gavage. The regimens were given once daily for a period of eight weeks. At the end of the experiment, the rats were sacrificed and serum samples were obtained for the analysis of total proteins, albumin, globulin, urea, Na + , K + , Cl - , and activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH). There was an increase in the concentration of Na + (P < 0.0001) concentration, albumin (P < 0.01) and a decrease in urea (CBZ and PHE groups) (P < 0.05), globulin (P < 0.05) and K + (CBZ group) (P < 0.05) concentrations. The activities of ALT in the CBZ and CBZ+PHE groups and that of AST activity in the PHE group increased significantly (P < 0.05). In conclusion, administration of CBZ and/or PHE induced significant alterations in serum biochemical parameters in Wistar rats. It is recommended that serum biochemical parameters should be strictly monitored and regularly evaluated in individuals treated with CBZ and/or PHE in order to alleviate or prevent some of these changes.

Ameliorative Effect of Vitamin E on Sensorimotor and Cognitive Changes Induced by Chronic Chlorpyrifos Exposure in Wistar Rats

The use of pesticides is inevitable in contemporary world because of their role in the improvement of food production through increase in crop yields and quality, reduction of farm labour requirements hence lowering cost of production, and improving public health through control of vector and vector-borne diseases (Weiss et al., 2004). Despite all these benefits, pesticides constitute menace to the health of man, animals and even the environment. This is because they are poorly selective and are toxic to non-target species, including humans. The segments of the population that are at the greatest risk of exposure are those that are occupationally exposed, such as agricultural workers. Despite the strict measures put in place concerning its commercialization and use, pesticides sales has increased in recent years (Carlock et al., 1999). The World Health Organization (WHO) estimated that about 3 million cases of acute intoxication and 220,000 deaths are attributable to pesticides each year with majority of these cases occurring in less developed countries (He, 2000; Clegg & van Gemert, 1999), particularly in Africa, Asia, Central America, and South America (Pancetti et al., 2007). Although many pesticides cause neurotoxicity, insecticides are the most acutely neurotoxic to humans and other non-target species compared to other pesticides (Costa et al., 2008). Association between acute exposure to pesticides and neurotoxicity is well known (Lotti, 2000) but the potential effects of chronic low-level exposure are less well established (Alavanja et al., 2004; Ambali et al., 2010a; Ambali & Aliyu, 2012). Organophosphate (OP) compounds are one of the most widely used constituting about 50% global insecticide use (Casida & Quistad, 2004). Studies in humans showed neurological, cognitive and psychomotor impairments following cumulative exposure to OPs and organochlorines in people from agricultural communities, without history of acute poisoning (Kamel & Hoppin 2004; Kamel et al., 2007). Neurobehavioural changes following low-dose OP exposure have been reported in sheep farmers (Stephens et al., 1995),