Effect of Thunbergia laurifolia, a Thai natural product used to treat drug addiction, on cerebral activity detected by functional magnetic resonance imaging in the rat.
BACKGROUND
Thunbergia laurifolia Linn. (TL) is an herbal medicine used to treat alcohol and drug addiction in Thai traditional medicine. A previous study demonstrated that an extract of TL increases rat striatal dopamine release in vitro.


OBJECTIVE
This study determined whether a methanol extract of TL altered rat brain region activity using in vivo functional nuclear magnetic resonance imaging (fMRI) in a manner consistent with the observed effects in vitro on dopamine release.


METHODS
fMRI was performed on a 2.35-T Bruker MR system. MR images were acquired from rat brain using the rapid acquisition relaxation enhanced sequence (field of view 50 mm). The imaging parameters used for the anatomical scan yielded an in-plane spatial resolution of 0.2x0.2 mm. Consecutive single-slice functional imaging over the rat brain investigated the changes in signal intensity in various parts of the brains induced by TL (200 mg/kg, i.p.) or vehicle administration.


RESULTS
These demonstrate that TL increased signal intensity in various brain areas such as nucleus accumbens, globus pallidus, amygdala, frontal cortex, caudate putamen and hippocampus. These are similar to those reported previously to show effects after either cocaine or amphetamine administration. Physiological variables were not affected by the injection of TL (200 mg/kg, i.p.), but there was a small decrease in arterial blood pressure.


CONCLUSIONS
The results indicate that TL increases significant neuronal activity in specific brain regions responsible for reward and locomotor behaviour (fixed-effect analysis); however, there is no significant difference between TL and vehicle-treated groups with random-effect analysis (population statistic). The active compound(s) in TL responsible for the pharmacological effects of TL remain to be identified.
Department of Physiology, Faculty of Medicine, Srinakharinwirot University, Sukhumvit 23, Wattana, Bangkok, 10110, Thailand. watchare@swu.ac.th
Watchareewan
W
Thongsaard
Charles A
CA
Marsden
Peter
P
Morris
Malcolm
M
Prior
Yasmene B
YB
Shah
D027901:Acanthaceae / Q000737:chemistry*; D000704:Analysis of Variance; D000818:Animals; D001784:Blood Gas Analysis / Q000379:methods; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000033:anatomy & histology / Q000098:blood supply / Q000187:drug effects*; D001931:Brain Mapping; D002560:Cerebrovascular Circulation / Q000187:drug effects; D007839:Functional Laterality; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging; D010100:Oxygen / Q000097:blood; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D013997:Time Factors
D010936:Plant Extracts; D010100:Oxygen