g(m1)-ganglioside and 6-hydroxydopa

Brain-derived neurotrophic factor (BDNF) supports the survival of sensory neurons as well as retinal ganglion cells, basal forebrain cholinergic neurons, and mesencephalic dopaminergic neurons in vitro. Here we examined the ability of BDNF to confer protection on cultured dopaminergic neurons against the neurotoxic effects of 6-hydroxyDOPA (TOPA or 2,4,5-trihydroxyphenylalanine), a metabolite of the dopamine pathway suggested to participate in the pathology of Parkinson's disease. Cells prepared from embryonic day 14-15 rat mesencephalon were maintained with 10-50 ng/ml BDNF for 7 days prior to addition of TOPA (10-30 microM) for 24 hr. In BDNF-treated cultures, the extensive loss (> 90%) of tyrosine hydroxylase immunopositive cells was virtually (< 10%) eliminated, while the equally drastic loss (> 90%) of the overall cell population was limited to only a 25-30% recovery. Furthermore, the monosialoganglioside GM1 (1-10 microM), although inactive alone, acted synergistically with subthreshold amounts of BDNF to rescue tyrosine hydroxylase-positive cells against TOPA neurotoxicity. These results add impetus to exploring the therapeutic potential of gangliosides and BDNF in Parkinson's disease.

Topics: Animals; Brain-Derived Neurotrophic Factor; Cell Survival; Cells, Cultured; Dihydroxyphenylalanine; Dopamine; Female; G(M1) Ganglioside; gamma-Aminobutyric Acid; Mesencephalon; Nerve Degeneration; Nerve Tissue Proteins; Neurons; Pregnancy; Rats; Recombinant Proteins; Tyrosine 3-Monooxygenase

The semisynthetic glycosphingolipid derivative II3Neu5-AcGgOse4-2-d-erythro-1,3-dihydroxy-2-chloro-acetamid e-4-trans- octadacene (LIGA20) attenuated injury induced by the excitotoxic L-dopa metabolite 2,4,5-trihydroxyphenylalanine (TOPA) in cultures of rat cerebellar granule cells when presented simultaneously with TOPA (EC50; 9 microM LIGA20). The natural glycosphingolipid ganglioside GM1 up to 200 microM was not neuroprotective as cotreatment, although pretreatment of cells for 2 h was efficacious. This greater potency and speed of LIGA20 action extended to limiting TOPA-induced death of cultured mesencephalic dopaminergic neurons. These data suggest that LIGA20 may have therapeutic potential for the treatment of disorders associated with excitotoxic processes.

Topics: Animals; Cells, Cultured; Cerebellum; Dihydroxyphenylalanine; G(M1) Ganglioside; Glycosphingolipids; Neurons; Parkinson Disease; Rats; Sphingosine

The neurotoxic properties of 2,4,5-trihydroxyphenylalanine (TOPA; the 6-hydroxylated derivative of dopa) was investigated in cultures of central neurons. Application of solutions of TOPA to cerebellar granule cells resulted in a concentration- and time-dependent neuronal death, with prolonged (24 hr) exposure producing a clear left-handed shift in the dose-response relationship from the one observed with a 60-min exposure (LD50: 4 and 29 microM, respectively). This toxicity was largely blocked by the non-N-methyl-D-aspartate antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. Solutions of TOPA were also toxic to mesencephalic neurons after acute or chronic exposure, displaying the same leftward shift in LD50. This latter preparation contained a minor population of dopaminergic, tyrosine hydroxylase immunopositive cells which were likewise sensitive to the excitotoxic effects of TOPA. Neurotoxic activity of TOPA appeared to depend upon its oxidation in solution, as judged using chemical analysis and reducing agents. The monosialoganglioside GM1 was effective in protecting against neurodegeneration induced by brief or prolonged exposure to solutions of TOPA. These results suggest that an abnormal production or accumulation of TOPA or its oxidation product(s) might be involved in excitotoxicity directed to areas of the brain with dopaminergic innervation, and in other brain areas in Parkinson's disease patients on long-term dopa therapy. The selective action of gangliosides in disrupting the pathological consequences of glutamate receptor activation proposes their use as chemoprophylactic agents for preventing or arresting the neuronal losses accompanying such situations.

Topics: 6-Cyano-7-nitroquinoxaline-2,3-dione; Animals; Cells, Cultured; Cerebellum; Dihydroxyphenylalanine; G(M1) Ganglioside; Mesencephalon; MPTP Poisoning; Oxidation-Reduction; Parkinson Disease; Quinoxalines; Rats; Rats, Sprague-Dawley