IN VIVO INHIBITION OF RAT BRAIN PROTEIN SYNTHESIS BY l-DOPA
Article first published online: 4 OCT 2006
Journal of Neurochemistry
Volume 23, Issue 1, pages 233–239, July 1974
How to Cite
Roel, L. E., Schwartz, S. A., Weiss, B. F., Munro, H. N. and Wurtman, R. J. (1974), IN VIVO INHIBITION OF RAT BRAIN PROTEIN SYNTHESIS BY l-DOPA. Journal of Neurochemistry, 23: 233–239. doi: 10.1111/j.1471-4159.1974.tb06939.x
- Issue published online: 4 OCT 2006
- Article first published online: 4 OCT 2006
- Revision received 28 January 1974. Accepted 29 January 1974
Abstract— A study has been made of the effect of a single intraperitoneal dose of l-DOPA on the in vivo metabolism of [14C]leucine and [14C]lysine by the brain, and on their uptake into brain protein. Administration of 500 mg DOPA/kg to 40-g rats raised the concentrations of several free amino acids; the only amino acid which underwent a statistically significant increment was alanine. Intracisternally-injected [U-14C]leucine was rapidly metabolized to other labelled compounds; DOPA administration did not influence significantly the rate of its metabolism. No similar metabolic change was observed after administering [U-14C]lysine intracisternally.
Incorporation of [14C]leucine and [14C]lysine into total brain protein was significantly reduced 45 min after DOPA administration. There was also depression of the uptake of labelled amino acid into a supernatant fraction, obtained by high speed centrifugation of the brain homogenate, and into brain microtubular protein (tubulin). Reduced amino-acid incorporation into brain proteins observed 45 min after l-DOPA injection coincided with extensive disaggregation of brain polyribosomes. At 120 min after DOPA treatment, disaggregation was no longer significant and there was a smaller depression in labelled amino aicd incorporation, which disappeared completely 240 min after l-DOPA injection. It is concluded that disaggregation of brain polysomes following DOPA treatment is an accurate reflection of a change in the intensity of brain protein synthesis in vivo.