Damodaran, Thenmoly K
(2018)
Studies Of Clitoria Ternatea Linn. Root
Extract On Behavioural Effects And In
Vivo Hippocampal Synaptic Plasticity In
A Rat Model Of Chronic Cerebral
Hypoperfusion.
PhD thesis, Universiti Sains Malaysia.
Abstract
Clitoria ternatea Linn. (CT) is a native plant in tropical countries like
Malaysia. The root part of the plant has been studied extensively for its
pharmacological activities. However, its contribution towards learning and memory
enhancement together with in vivo synaptic plasticity in a chronic cerebral
hypoperfusion (CCH) rat model has yet to be explored. For quality control purposes,
taraxerol content (0.15% ± 0.01) in the methanolic extract of CT root was determined
using validated gas chromatography-mass spectrometry (GC-MS) analytical method.
In the present study, the permanent bilateral occlusion of common carotid arteries
(PBOCCA) surgery method was employed to develop CCH model in rats. The acute
and chronic (28 days) treatment of CT root extract at doses of 200 and 300 mg/kg,
p.o. resulted in a significant enhancement in memory retention of the passive
avoidance task. Effects of CT root extract were further assessed in the Morris water
maze task. The results demonstrate that CT root extract (200 and 300 mg/kg, p.o.)
treatment restored spatial learning and reference memory impairments induced by
CCH. Chronic treatment of CT root extract (200 and 300 mg/kg, p.o.) was also found
to diminish CCH-induced neuronal damage in the CA1 region of the hippocampus.
An increased acetylcholinesterase (AChE) activity in the frontal cortex and
hippocampus of the PBOCCA rats was significantly inhibited by the CT root extract
at a high dose (300 mg/kg, p.o.). In synaptic plasticity study, CT root extract (200 and 300 mg/kg, p.o.) restored the CCH-induced in vivo hippocampal long-term
potentiation (LTP) suppression at the Schaffer collateral CA3-CA1 synapse. These
results indicate that CT root extract may affect learning and memory functions in
PBOCCA rats via LTP facilitation. CT root extract (300 mg/kg, p.o.) did not show
any improvement on spatial memory and hippocampal LTP in scopolamine
(muscarinic receptor antagonist; 1.0 mg/kg, i.p.) pre-treated PBOCCA rats. In
toxicity study, repeated doses of CT root extract (100, 200 and 300 mg/kg, p.o.) were
found to be safe in PBOCCA rats after 28 days treatment. In conclusion, the
methanolic extract of CT root extract restored the learning and memory deficits and
in vivo synaptic plasticity impairment in a CCH rat model, thus supporting the
therapeutic potential of CT root extract in the treatment of vascular dementia (VaD).
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