Doraisamy, Thilageswary a/p
(2022)
The effects of chronic administration of mitragynine on cortical oscillations in rats.
Masters thesis, Universiti Sains Malaysia.
Abstract
Mitragynine is the significant alkaloid extracted from the leaves of M. speciosa
(Kratom). The leaves have been extensively used to relieve pain as well as to aid in
opioid withdrawal symptoms. Previous studies have recorded that drug do affect
cognitive mechanisms in human yet the debate over the potential side effects of the
drug which includes addiction risk and cognitive decline is still ongoing and also its
underlying neural activity remains unclear. Thus, this study was designed to
investigate the changes in brain spectral power and theta coherence after repeated
exposure to mitragynine in freely moving rats. Male Sprague-Dawley rats was
implanted with electrodes on right and left frontal cortex, hippocampal cornu ammonis
(CA1), subiculum and sensory cortex for wireless EEG recording. Mitragynine (1, 5,
and 10 mg/kg) was administered for 28 days, and EEG activity was recorded on day
7,14,21 and 28. The readings was transmitted to receiver and analyzed for different
frequency range, delta (0.1-4Hz), theta (4-7Hz), alpha (7-13Hz) and beta (13-30Hz).
The results have demonstrated frequency specific changes in spectral power occurring
selectively in both cortical and hippocampal regions. In cortical regions, a general
increase in beta power with collateral reduction in alpha power is seen as novel effects
of mitragynine, while a reduction in delta power is appreciated in both cortical and
hippocampal regions. Mitragynine induced reduction in theta coherance (4-7Hz) was
seen as disruptions in functional connectivity between left frontal cortex and sensory
cortex. It can be concluded that, these findings show mitragynine induced frequency specific changes in cortical neural oscillatory activity and suppressed theta coherence
could potentially impact cognitive functioning.
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