Homocysteine Intracerebroventricular Injection Induces Apoptosis in the Substantia Nigra Cells and Parkinson's Disease LikeBehavior in Rats

Parkinson's disease is a degenerative disorder of the central nervous system. The motor symptoms of Parkinson's disease result from the death of dopamine-generating cells in the substantia nigra, a region of the midbrain; the cause of this cell death is unknown. Homocysteine (Hcy) is a non-protein amino acid. It is a homologue of the amino acid cysteine. The elevated levels of homocysteine in plasma have been associated with a number of disease states. Hcy (2 µmol / µl) was injected intracerebroventricular (i.c.v) in rats, five days later, the locomotor activity was measured with open field apparatus, Also apoptosis was investigated in substantia nigra cells by immunohistochemical analysis. Hcy could decrease locomotor activities significantly in rats as well as it could induce apoptosis in substantia nigra cells. These results suggest that Hcy is a neurotoxic metabolite and may induce cell death in some nuclei in the brain.