Abrin is a potent plant toxin. It is a heterodimeric protein toxin which is obtained from the seeds of Abrus
precatorius plant. At cellular level abrin causes protein synthesis inhibition by removing the specific
adenine residue (A4324) from the 28s rRNA of the 60S – ribosomal subunit. In the present study we
investigated the role of oxidative stress in neurotoxic potential and demyelinating effects of abrin on
brain. The mechanism by which abrin induces oxidative damage and toxicity in brain are relatively
unknown. Animals were exposed to 0.4 and 1.0 LD50 abrin dose by intraperitoneal route and observed for
1 and 3 day post-toxin exposure. Oxidative stress occurred in brain due to abrin was confirmed in terms
of increased reactive oxygen species (ROS), glutathione depletion and increased lipid peroxidation.
Significant increase in blood and brain ROS was observed at day 3, 1 LD50. Abrin induced changes in the
neurotransmitters (5-hydroxy tryptamine, norepinephrine, dopamine and monoamine oxidase) levels
were evaluated by spectroflourometry. Increase in the levels of 5-HT and NE was observed after abrin
exposure. MAO activity was found to be decreased in abrin exposed animals compared to control.
Significant inhibition in the activity of acetylcholine esterase enzyme in brain and serum was reported
for both the doses and time points. Western blot analysis of iNOS expression indicated that abrin
treatment resulted in dose and time dependent increase. Furthermore, protein expression of myelin
basic protein (MBP) was down regulated in a dose and time dependent manner. Brain histopathology
was carried out and cortical brain region showed demyelination after abrin exposure. Results confirmed
that abrin poisoning leads to neurodegeneration and neurotoxicity mediated through oxidative stress,
AChE inhibition, lipid peroxidation and decrease in MBP levels.