NMNAT3 and Parkinson disease: Instead, we assessed the expression of NMNAT3 in NDC and PD SN using confocal microscopy and quantitatively compared the degree of colocalization between tyrosine hydroxylase (TH)-positive neurones and NMNAT3, using colocalization with glial acidic fibrillary protein (GFAP)-positive glia as a control (Fig. 3).