Ahmad Nazri, Mohd Ulul Ilmie
(2015)
The electrophysiological and behavioural effects of SSubchronic administration of standardised methanolic Mitragyna speciosa extract on adult male sprague-dawley
Rats.
Masters thesis, Universiti Sains Malaysia.
Abstract
The research on Mitragyna speciosa Korth or known as ketum has been carried out to
determine its effects towards learning and memory as well as its toxic effects on animals
that have been exposed subchronically. There were three objectives in the present study.
The first objective was to study the electrophysiological characteristics of standardised
methanolic Mitragyna speciosa extract (SMMSE) on hippocampal slices of rats that
were exposed to subacute (14 days) and subchronic (28 days) treatment via its effect on
long-term potentiation (LTP). The second objective was to study the effects of
subchronic SMMSE towards cognitive function by using passive avoidance (PA) test.
The last objective was to study the toxicity effects of subchronic SMMSE exposure on
organ histopathology, haematology and biochemical parameters. For the first objective,
animals were divided into four groups; control, MS100 (100 mg/kg SMMSE), MS200
(200 mg/kg SMMSE) and MS500 (500 mg/kg SMMSE). LTP recording of animals that
were exposed to SMMSE for 14 days showed that LTP induction was partially blocked.
Meanwhile, the exposure for 28 days showed that LTP induction was totally blocked.
For the second objective, animals were divided into five groups; control, MS100,
MS200, MS500 and additional morphine group (10 mg/kg). In the passive avoidance
test, all groups learned in the acquisition phase. Meanwhile, in the retention phase,
subchronically exposed groups showed the improvement in memory, especially MS500.
For the last objective, all doses of SMMSE were potentially toxic to the body.
Histopathology analyses showed that organs affected by the toxicity of subchronic
SMMSE were liver, kidney and lungs. Toxic effects were also seen in the biochemical
analyses especially on AST (aspartate aminotransferase), creatinine, globulin, glucose,
total protein as well as urea. In contrast, there were no significant differences for
hematology tests. In conclusion, subchronic exposure of ketum was able to improve
learning and memory. However, the main mechanism of learning and memory which
was LTP was totally inhibited by the extract. The subchronic exposure of the extract was
also toxic to the liver, lung and kidney.
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