Glia-conditioned medium offers protection against the toxicity induced by 6-OH-dopamine in vivo

Introduction. Glia-conditioned medium (GCM) is neurotrophic for dopaminergic (DA) neurons and protects against MPP+ toxicity in vitro. We present the data from the first study in vivo of the effects of GCM. Material and methods. The 'restorative' effects were examined in rats with lesions produced by 6-hydroxy-dopamine (6-OH-DA) in the medial longitudinal fasciculus. At four weeks, animals with an apomorphine-induced rotation rate above three per minute were randomised for infusion with GCM, defined medium (DM) or saline through a striatal cannula for two weeks. To investigate the 'protective' effects of GCM, the animals received a striatal injection of GCM or vehicle at the same time as the lesion was induced by 6-OH-DA and were sacrificed three weeks later. Results. In the experiments on the 'restorative' effect, the GCM infusion produced a significant increase in dopamine (DA) levels on the side with the lesion, in the limbic system (455.8 +/- 108.4 ng/g of tissue) and in the striatum (242.1 +/- 69.2 ng/g of tissue), as compared with the controls (110.8 +/- 36,4 and 108.4 +/- 22 ng/g). In the experiments on the 'protective' effect, GCM induced higher levels of DA, 3,4-dihydroxyphenylacetic acid and 3-methoxytyramine (3-MT). In both models, the apomorphine-induced rotation in animals with lesions caused by 6-OH-DA and treated with GCM was lower than that of the animals infused with DM or saline. Conclusions. These experiments show that GCM has protective and restorative effects in an experimental model of Parkinson's disease.