Minocycline Protects Dopaminergic Neurons Against Long-Term Rotenone Toxicity

Background: In Parkinson's disease, most of current therapies only provide symptomatic treatment and so far there is no drug which directly affects the disease process. Objectives: To investigate the neuroprotective effects of minocycline against long-term rotenone toxicity in primary dopaminergic cell Cultures. Methods: Embryonic mice of 14-days-old were used for preparation of primary dopaminergic cell cultures. On the 6th day in vitro, prepared cultures were treated both with minocycline alone (1, 5, 10 and 20 mu M) and concomitantly with rotenone (5 and 20 W) and minocycline. Cultures were incubated at 37 degrees C for six consecutive days. On Day 12 in vitro culture medium was aspirated and used for measuring lactate dehydrogenase. Cultured cells were fixed in 4% paraformaldhyde and stained immunohistochemically against tyrosine hydroxylase. Results: Treatment of cultures with 5 and 20 nM of rotenone significantly decreased the survival of tyrosine hydroxylase immunoreactive neurons by 27 and 31% and increased the release of lactate dehydrogenase into the culture medium by 3 1 and 236%, respectively compared to untreated controls. Minocycline (1, 5, 10 mu M) significantly protected tyrosine hydroxylase immunoreactive neurons by 17, 15 and 19% and 13, 22 and 23% against 5 and 20 nM of rotenone, respectively compared to rote non e-treated Cultures. Minocycline (only at 10 mu M) significantly decreased the release of lactate dehydrogenase by 79% and 133% against 5 and 20 nM of rotenone, respectively. Conclusion: Minocycline has neuroprotective potential against the progressive loss of tyrosine hydroxylase immunoreactive neurons induced by long-term rotenone toxicity in primary dopaminergic cultures.