EVALUATION OF THE PROTECTIVE EFFECT OF AQUEOUS AND ETHANOL FRUIT EXTRACTS OF Phoenix dactylifera L. ON MERCURY - INDUCED NEUROTOXICITY IN WISTAR RATS
EVALUATION OF THE PROTECTIVE EFFECT OF AQUEOUS AND ETHANOL FRUIT EXTRACTS OF Phoenix dactylifera L. ON MERCURY - INDUCED NEUROTOXICITY IN WISTAR RATS
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Date
2017-04
Authors
AGBON, ABEL NOSEREME
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Abstract
In this study, evaluation of the protective effect of aqueous and ethanol fruit extracts of Phoenix dactylifera L. on mercury-induced neurotoxicity in Wistar rats, phytochemical screening of P. dactylifera fruit extracts (aqueous and ethanol) revealed the presence of flavonoids, saponins, tannins and alkaloids. The protective effect of the extracts were assessed on mercury-induced cerebral, cerebellar and hippocampal neurotoxicity in Wistar rats. Evaluation of the protective effect of P. dactylifera fruit extracts involved the following investigations: brain morphological studies; histometry of pyramidal cells of cerebral cortex- layer V and CA1 and CA3 hippocampal regions, and Purkinje cells of the cerebellar cortex; routine histological and histochemical studies of cerebral and cerebellar cortices, and hippocampus (CA1 and CA3 regions); neurobehavioural studies employing elevated plus maze (EPM) to assess anxiety-related behavior, transfer latency (TL) on EPM open arm and Morris water maze (MWM) to evaluate learning and memory, forelimb grip strength (FGS) test to assess muscular strength in the forelimbs and beam walking test (BWT) to monitor motor coordination and balance of Wistar rats; neurochemical analysis to assess the concentration of neuro-trace elements (copper, Cu; iron, Fe; manganese, Mn and zinc, Zn) in brain-tissue homogenate and biochemical analysis to assess lipid peroxide levels and antioxidant enzyme activity (malondialdehyde, MDA; superoxide dismutase, SOD; catalase, CAT and glutathione peroxidase, GPx) in blood serum and brain-tissue homogenate, and acetylcholinesterase (AchE) activity for endogenous enzyme in brain-tissue homogenate of Wistar rats. Seventy-two (72) Wistar rats (male and female) were divided into two experimental categories: 1 (twenty-four (24) rats, consisting of three groups; I - III served as the common groups) and 2 (forty-eight (48) rats, subdivided into treatment categories: A and B of twenty-four (24) rats each, consisting of three groups; IV - VI). Thus, each category consisted of six groups (I - VI) of eight rats each. Group I served as control and was administered distilled water (0.5 ml) while, groups II - VI were treatment groups. Neurotoxicity was induced in rats by the administration of mercury – mercuric chloride (HgCl2). Group II was administered HgCl2 (5 mg/kg); group III was administered vitamin C (100 mg/kg) as reference drug; groups IV, V and VI were administered fruit extract of P. dactylifera (250 mg/kg, 500 mg/kg and 1,000 mg/kg,
respectively) followed, concomitantly, by HgCl2 (5 mg/kg) for a period of two weeks. Rats in category A were administered aqueous fruit extract of P. dactylifera (AFPD), while category B were administered ethanol fruit extract of P. dactylifera (EFPD); all administrations were via oral route. Results revealed that, exposure to HgCl2 resulted in neurotoxicity in rats, which was evident from morphologic, histometric, histologic and histochemical alterations in brain; HgCl2 induced anxiety-related responses, short- and long-term memory impairments and motor deficits in neurobehavioural assessment and, altered the levels of neurochemical and biochemical constituent in rats. However, administration of AFPD and EFPD revealed the potentials of the extracts as neuroprotective agent in the following ways: brain morphologic features and histometric characteristic of brain regions (cerebral and cerebellar cortices and hippocampus) were preserved relative to the control; histologic and histochemical alterations in cerebral and cerebellar cortices and hippocampal regions (CA1 and CA3) were ameliorated relative to the control; anxiety-related responses, short- and long-term memory impairments, and motor coordination and balance deficits in neurobehavioural assessment were ameliorated relative to the control; Alterations in the concentration levels of neuro-trace elements (Fe, Mn, Cu and Zn), MDA and endogenous antioxidants (SOD, CAT, GPx), and endogenous enzyme (AchE) activity levels were moderately ameliorated relative to the control. The neuroprotective property of extracts, relative to the reference (vitamin C), is rather similar, and is attributed to antioxidant properties of constituent phytochemicals, such as flavonoids. Neuroprotective activity was dose dependent; 500 and 1,000 mg/kg doses possessing maximal activity for both extracts – with EFPD more efficacious. In conclusion, findings suggest that, AFPD and EFPD are potentially efficacious in ameliorating mercury-induced alterations in the brain (cerebral and cerebellar cortices and hippocampus) of Wistar rats and could be potential candidates for application in the management and treatment of reactive oxygen species-induced neurodegenerative diseases
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF DOCTOR OF PHILOSOPHY (Ph.D) DEGREE IN HUMAN ANATOMY
DEPARTMENT OF HUMAN ANATOMY
FACULTY OF MEDICINE
AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA
Keywords
EVALUATION,, PROTECTIVE EFFECT,, AQUEOUS,, ETHANOL FRUIT EXTRACTS,, Phoenix dactylifera L,, MERCURY - INDUCED NEUROTOXICITY,, WISTAR RATS,