[P204]: A conditional knock‐out tool to study midbrain dopaminergic neuron development

granular pattern around the nucleus, suggesting uptake of the protein. To examine the importance of neuronal internalisation of MT, rabbit liver MT-II was immobilised on a glass coverslip and rat cortical neurons were grown on this MT substrate for 24 h. Neurites extending from neurons on the MT substrate were significantly greater than those extending from neurons plated on poly-l lysine (PLL), however this appears to reflect an inhibitory influence of the latter substrate, since there was no significant differences between neurons plated on MT substrates or uncoated glass. When an MT substrate was combined with a PLL substrate, MT did not appear to overcome PLL induced inhibition of neurite outgrowth. In contrast, MT applied in solution is able to overcome PLL inhibition. This study suggests that internalisation of MT is required for its ability to promote regenerative sprouting from neurons, and further investigation involving neuronal transfection with an MT expressing vector, and other methods of immobilisation of MT are being explored.