Low selenium diet induces tyrosine hydroxylase enzyme in nigrostriatal system of the rat

We have studied the effect of a selenium-deficient diet on the nigrostriata l dopaminergic system for 15 and 30 days. The neurochemical analysis demons trated significant elevations in nigral DA levels after 15 and 30 days of s elenium deficiency. The most significant change in striatum was an elevatio n in dopamine (DA) in 30-day-deficient animals. As a further step, we measu red the levels of activity and mRNA expression of tyrosine hydroxylase (TH) and dopamine transporter (DAT). There were significant elevations in all o f these parameters in the nigrostriatal system following selenium deficienc y at the two lime-points studied except for the striatal DA uptake at day 3 0, which dropped to control levels. Altogether, our results suggest that th e decrease in antioxidant capacity due to a selenium deficiency promotes an increase in DA synthesis and turnover, which are clearly associated to the induction of TH. This effect may trigger a positive feed-forward mechanism that could increase the oxidative stress considering the capacity of DA to generate free radicals. (C) 2000 Elsevier Science B.V. All rights reserved .