IDENTIFICATION OF A 12.5-KD PROTEIN FROM CAUDATE-PUTAMEN NUCLEUS AS ADOPAMINERGIC NEURONOTROPHIC FACTOR

The effect of the extract from caudate-putamen nucleus of newborn rats (CPe) on the dopaminergic (DA) neurons has been studied. An MTT color imetric microassay measuring optical densities for the growth of DA ne uron cultures reveals a significant increase in growth for cultures wi th CPe as compared to those without CPe (p < 0.05). Rhodamine retrogra de-prelabelled DA neurons were cultured on a Phastgel containing all t he electrophoretically separated protein bands from CPe, and able to f ish out from it their own trophic factor, a 12.5-kD protein band. The survived neurons at the 12.5-kD protein band were immunostained positi ve with anti-dopamine antibody. Co-culturing the 12.5 kD-containing ge l strip with explants from substantia nigra at a close distance for a week revealed anti-dopamine immunopositive neurites outgrowing from th e explants only towards the 12.5-kD gel strip. These results indicate that a 12.5-kD protein from the CPe is capable of maintaining the surv ival of DA neurons of the substantia nigra and promoting their neurite outgrowth.