Long-term effect of kainic acid on striatal dopaminergic neurons

Abstract

Summary The effect of intrastriatally injected kainic acid (KA) on dopamine (DA) and DOPAC content, synaptosomal DA synthesis and soluble tyrosine hydroxylase (TH) activity in the caudate nucleus (CN) was studied at 40 and 150 days after lesion. Since tissue weight decreased to 70 and 30% of the control side, respectively, at these time intervals, the results were expressed per whole CN. The following changes were observed: a) DA levels were decreased to 70 and 45% of the untreated side at 40 and 150 days after KA administration, respectively; b) both DOPAC content and soluble TH activities were reduced to approximately 50 and 30% of the control at 40 and 150 days after treatment, respectively; c) synaptosomal DA synthesis was reduced to 30% of the control at 40 days and remained so at 150 days after KA. KA failed to modify the K m of TH, whereas the V max was decreased to 45 and 25% of controls at 40 and 150 days after treatment respectively. The results indicate that, after a long lag period, KA produces a reduction in striatal dopaminergic neurons.