TH and Parkinson disease: A recent study [53] performed with a PD model similar to ours showed that while the detrimental effect of 6-OHDA on the TH+ fibres in the striatum was immediate, the loss of TH+ dendritic fibres and the reduction in cell size and intensity of TH expression, as well as the eventual reduction in the number of TH+ neurons in the substantia nigra, were delayed for several days after surgery.