AMELIORATIVE EFFECTS OF ASCORBIC ACID ON NEUROBEHAVIOURAL, HAEMATOLOGICAL AND BIOCHEMICAL CHANGES INDUCED BY SUB-CHRONIC LEAD EXPOSURE IN WISTAR RATS
AMELIORATIVE EFFECTS OF ASCORBIC ACID ON NEUROBEHAVIOURAL, HAEMATOLOGICAL AND BIOCHEMICAL CHANGES INDUCED BY SUB-CHRONIC LEAD EXPOSURE IN WISTAR RATS
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Date
2010-02
Authors
OLALEKAN, OLADIPO OLUSOLA
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Abstract
ABSTRACT
Experiments were performed with the aim of evaluating the effects of sub-chronic exposure
to lead and the protective role of ascorbic acid on toxic changes in Wistar rats. Forty adult
Wistar rats (20 males and 20 females) divided into 4 groups of 10 animals each (5 males and
5 females in each group) served as subjects for this study. Rats in group I were given distilled
water only. Rats in group II were exposed to lead acetate only at 200 mg/kg, while those in
group III were pre-treated with ascorbic acid only at a dose of 100 mg/kg. Rats in group IV
were pre-treated with ascorbic acid at a dose of 100 mg/kg before being administered with
lead acetate 30 minutes later. The regimens were administered orally once daily for a period
of six weeks. The effects of the different treatments on body weight change, open-field
activities, sensorimotor reflexes and cognition were evaluated in the rats. Packed cell volume
(PCV), haemoglobin concentration (Hb), total erythrocyte count (RBC), total leucocyte
count, differential leucocyte count and erythrocyte osmotic fragility (EOF) test were
determined using standard methods. Total protein, albumin and globulin concentrations, and
activities of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST),
alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and creatine kinase (CK) were
measured using standard methods. Lipid peroxidation was determined by measuring the
thiobarbituric acid reactive substance; malondialdehyde (MDA) in the brain of the rats.
Serum thyroid hormone levels were also determined using radioimmunoassay. The results
demonstrated that sub-chronic exposure to lead in rats had no effect on body weight change.
There was no significant (P > 0.05) change in sensorimotor reflexes of the rats. Rats in the
lead-treated group showed an increased anxiety compared to the control and those pre-treated
with ascorbic acid. Rats in the lead group also showed a significant (P < 0.05) decline in
cognitive function compared to those in the control and ascorbic acid-pretreated groups. The
haematology showed significant (P < 0.05) reductions in PCV, Hb and RBC in the lead9
treated group compared to the control rats. Lead also caused leucocytosis due to a
significantly (P < 0.05) higher neutrophil/lymphocyte ratio. There was slight but insignificant
increase in EOF in rats exposed to lead, compared with the control groups. A significant (P <
0.05) decrease in AST, LDH, CK and a slight increase in MDA was observed in the lead
treated rats compared to the control groups. There were tissue changes in the lead-treated
group compared with the control and the ascorbic acid pre-treated groups. The study
demonstrated that increased lipid peroxidation, low thyroid indices and decreased CK activity
may be involved in the mechanism of neurobehavioural and cognitive impairments by lead.
In conclusion, the study showed that sub-chronic exposure to lead induced anxiogenic effects,
cognitive, haematological, biochemical and pathological changes in rats, ameliorated by
pretreatment with ascorbic acid. It is, therefore, recommended that individuals, who are
constantly exposed to lead, should be pretreated with vitamin
Description
DEPARTMENT OF VETERINARY PHYSIOLOGY AND
PHARMACOLOGY
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA.
Keywords
PARTIAL,, FULFILLMENT,, REQUIREMENTS,, AWARD,, DEGREE,, MASTER,, SCIENCE,, VETERINARY,, TOXICOLOGY