THE EFFECTS OF MERCURY ON THE HIPPOCAMPUS, CEREBELLAR AND CEREBRAL CORTICES OF ADULT WISTAR RATS
THE EFFECTS OF MERCURY ON THE HIPPOCAMPUS, CEREBELLAR AND CEREBRAL CORTICES OF ADULT WISTAR RATS
No Thumbnail Available
Date
2012-12
Authors
ADAMU, ABUBAKAR SADEEQ
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Mercury is a widespread environmental and industrial pollutant which is used in food
preservation, cosmetics, pharmaceutical companies and laboratories. The aim of the
present study was to investigate the possible effects of mercury (Hg) exposure on the
histomorphology of the hippocampus, cerebellar and cerebral cortices, and also to
evaluate the effects of mercury on spatial learning and memory, and motor activity
with the aid of Morris water maze and Montoya staircase tests respectively. Twenty
four adult Wis-tar rats of both sexes, with average weight of 210gms were randomly
divided into four groups I, II, III, and IV with six animals per group. The animals in
groups II, III, and IV were administered mercury chloride orally at the concentration
of 12.45, 24.9 and 49.8 mg/kg body weight respectively while group I served as
control and was administered with normal saline. The administration lasted for a
period of 21 days (3 weeks). Animals were trained for both spatial learning and
memory, and motor function using Morris water maze and Montoya stair case tests
respectively. The brain tissues was fixed in Bouin’s fluid and processed for
histopathological studies using H and E and Bielschowsky stains. Brain tissues were
analyzed for trace element analysis using Neutron Activation Analysis (NAA-1). The
results from spatial learning and memory test was statistically significant after the
first week of administration of mercury chloride in group IV animals, by the second
week, there was an increase in time to find the platform, also by third week of
exposure to low dose of mercury, there was a statistical significant increased in latency
time taken to find the platform as an escape route by the rats. The result from Montoya
- 14 -
staircase test showed reduced exploratory motor activity in rats exposed to high
concentration of HgCl2 that was statistically significant in the third week. There was
significant motor exploratory activity impairment due to mercury intoxication even at
low doses. The trace element analysis with NAA-1 revealed a significant decrease in
concentration of copper and zinc in the brain tissues of rats exposed to mercury The
results also showed neurodegenerative changes in the hippocampus, cerebral and
cerebellar cortices which range from cellular death and sparse distribution of cells and
decreased in cell number which also contributed to the decreased in concentration of
the copper and zinc concentrations in the hippocampus, cerebellar and cerebral
cortices as well as loss in motor activity, and memory and learning deficit. The
findings from this study showed that ingestion of mercury chloride has potential
deleterious effects on brain as shown in the histopathology, decreased cell number,
impairment of learning and memory, exploratory motor activity and reduction in
essential trace element concentrations in the brain of Wis-tar rats.
Description
A RESEARCH THESIS SUBMITTED TO THE SCHOOL OF POST
GRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA.
IN PARTIAL FULFILLMENT FOR THE AWARD OF MASTER OF SCIENCE
IN HUMAN ANATOMY
DEPARTMENT OF HUMAN ANATOMY, FACULTY OF MEDICINE,
AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA.
DECEMBER, 2012
Keywords
EFFECTS,, MERCURY,, HIPPOCAMPUS,, CEREBELLAR,, CEREBRAL,, CORTICES,, ADULT,, WISTAR RATS