SummaryThe induction of Parkinson's disease (PD) in senescence-accelerated mice (SAMP8) by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and the effects of dimethylsulfoniopropionate (DMSP) on induced PD model mice of SAMP8 were investigated for 5 wk. After many trials, the tail suspension test determining the PD symptoms indicated that an appropriate amount of MPTP clearly raises the SAMP8 mice to the PD-model mice. Moreover, DMSP administration to the PD-SAM model mice proved to completely reduce the PD symptoms in the mice and to accumulate large amounts of norepinephrine, dopamine and dioxyphenylacetate in the mouse brains without cerebellums. These results suggest that catecholamines accumulated in large quantities by the supplementation of DMSP to the double-diseased mice, PD-SAMP8 model mice, completely ameliorated the PD symptoms in these model mice. Key Words dimethylsulfoniopropionate, Parkinson's disease, senescence-accelerated mice, catecholamines A tertiary sulfonium compound, dimethylsulfoniopropionate (DMSP), is found in marine animals, especially green sea algae in large amounts ( 1 ), and has been customarily ingested in large and small amounts by a number of people in Japan for many years ( 2 ). We have examined the effects of DMSP on aquatic and terrestrial animals and obtained a variety of noticeable results ( 3 -9 ). In contrast, Parkinson's disease (PD) has proven to principally cause a deficiency in dopamine in the substantia nigra of the brain and sympathetically degenerates and/or degrades the dopaminergic-, norepinephrinergic-, and cholinergic-nervous systems in the brains, resulting in dementia in humans ( 10 -12 ). However, L-dopa does not completely recover the symptoms of PD ( 11 ), although L-dopa is proven to be the most effective among all the drugs used for curing this disease to date ( 11 ). We then examined the effects of DMSP on the PD-model mice induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyrimidine (MPTP), which indicated that addition of DMSP to the PD-model mice induced from C57BL6 mice effectively ameliorates the characteristic PD symptoms of PD-model mice elicited by MPTP ( 13 ). We further attempted to examine whether or not MPTP can induce parkinsonism in senescence-accelerated mice (SAM)P8 and whether DMSP exerts any effect on the PD-model mice of SAMP8, whose brains exhibit the characteristic properties of early aging (i.e., loss of learning and memory) ( 14 ).
Materials and MethodsDMSP was synthesized and purified to 99.8% purification (from element analysis) ( 3 ). 3,4-Dioxyphenylacetic acid (DOPAC) was obtained from Sigma-Aldrich Co., Ltd., Japan. All other chemicals were of the best available quality ( 13 ). The SAMP8 male mice were kind gifts from emeritus Prof. MD. Takeda T. in Kyoto University. The rearing conditions were the same as those in the previous report ( 13 ), except for the following experimental conditions. The twenty mice were divided into two groups, one fed distilled water (the control group) and the other DMSP solution at 5 ϫ 10 Ϫ 4 M...