Brain ischemia is a condition in
which there is insufficient blood flow
to meet its metabolic demands leading
to many functional and structural
changes.
The cerebellum is considered
one of the vulnerable regions
for
brain ischemia. Melatonin, produced
by the pineal gland, has antioxidant,
anti-inflammatory and antiapoptotic
effects. Therefore, the
current
study has been performed to
evaluate
the effect of melatonin administration
on induced ischemic reperfusion
injury (I/R) in rat cerebellar
cortex.
Thirty adult male albino rats
were
used and divided into three
groups
(10 rats / group). Group A
contained
the sham-control rats, while group B included I/R rats which
were subjected to transient ischemia
by ligation of both common carotid
arteries simultaneously for 10 minutes
and subdivided into 2 subgroups;
B1(3 days after I/R) and B2
(one
month after I/R). Group C included
I/R rats (as in group B) with
intraperitoneal
melatonin administration
(in a dose of 5 mg/ kg) 30 minutes
before performing ischemia and
one
& three hours after release of ligation
respectively and also was
subdivided
into 2 subgroups; C1 (3
days
after I/R with melatonin administration)
and C2 (one month after I/
R
with melatonin administration).
The
cerebellum was dissected and
prepared
to be stained with haema- toxylen and eosin (H&E). Also, immunohistochemical
study was performed
for detection of glial fibrillary
acidic
protein (GFAP) and p53 positive
cells. Subgroup B1 sections
showed
shrunken Purkinje cells and
apoptotic
granular ones which were
markedly
increased in number in
subgroup < br /> B2. These histological
alterations
were ameliorated in subgroup < br /> C1 sections with melatonin
administration.
The histological architecture
of cerebellar cortex of subgroup < br />C2 appeared more or less
similar
to the control group. Few p53
and
GFAP positive cells in rat
cerebellar
cortex of subgroup B1
were
observed with significant increase
in subgroup B2. However,
sections
of subgroups C1 and C2
showed
an apparent decrease in the
number
of positive cells of both immunohistochemical
markers as compared
to the corresponding B subgroups.
It could be concluded that injection
of melatonin could ameliorate
I/R
associated changes in rat cerebellar
cortex through a possible neuroprotective
role.