Antioxidant Formulae, Shengmai San, and LingGuiZhuGanTang, Prevent MPTP Induced Brain Dysfunction and Oxidative Damage in Mice

The present study was designed to evaluate the preventive effect of antioxidative traditional oriental medicine formulae, Shengmai San (SMS) and LingGuiZhuGanTang (LGZGT), against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (i.p 30 mg·kg⁻¹ for 5 consecutive days) induced neurotoxicity. In in vitro antioxidant assays measured with Trolox and butyl hydroxyl toluene as reference antioxidant revealed that SMS has higher scavenging potential against hydroxyl radical than superoxide anion radical, but LGZGT was the reverse. The neuroprotective effect of SMS and LGZGT against MPTP was evaluated in mice by behavioral, biochemical, and immunohistochemical studies. In the behavioral study, both SMS and LGZGT significantly reversed the locomotive impairment induced by MPTP. Simultaneously, both formulae significantly prevented the MPTP induced dopaminergic neuron loss assessed by tyrosine hydroxylase in the midbrain. Both SMS and LGZGT significantly attenuated the elevated lipid peroxidation and protein carbonyls levels by MPTP. The DNA damage induced by MPTP was also prevented by both formulae. Although a little difference in the protective functions was observed between the two formulae, such as in DNA damage and behavioral studies, the results indicate that both SMS and LGZGT with antioxidant property act as a good candidate applicable for the antioxidant based complementary therapies of neurodegenerative diseases.

Neural progenitor cells are protected against MPTP by MAO-B inhibitors

Neurotoxic effects of MPTP on the nigrostriatal dopaminergic system are thought to be initiated by 1-methyl-4-phenylpyridinium (MPP+), a metabolite formed by the monoamine oxidase (MAO)-B-mediated oxidation of MPTP. We previously reported that the administration of MPTP induced apoptosis in migrating neuroblasts (neural progenitor cells, NPCs) in adult mice. To determine whether MAO-B is also involved in the neurotoxicity of MPTP to NPCs, this study looked at the effects of MAO B inhibitors, R(-)-deprenyl (deprenyl) and N-(2-aminoethyl)-4-chlorobenzamide (Ro 16-6491), both of which protect the dopaminergic system against MPTP. Few apoptotic cells were found in saline- or MAO-B inhibitor-treated animals but MPTP markedly induced apoptosis in the subventricular zone (SVZ) and rostral migratory stream (RMS) after 1 day. When mice were pretreated with deprenyl or Ro 16-6491, not only nigrostriatal dopamine levels but also NPCs were significantly protected against MPTP. In addition, MPTP-induced apoptosis was found in both juvenile (postnatal 21 days) and older (12 months old) mice, suggesting NPCs to be different from the dopamine system, which has been thought to exhibit age-dependent susceptibility to MPTP.