Related Experiment Video
Updated: Feb 10, 2026

Induction and Assessment of Levodopa-induced Dyskinesias in a Rat Model of Parkinson's Disease
Published on: October 14, 2021
L-dopa methyl ester antagonizes competitively L-dopa-induced facilitation of noradrenaline release from rat
Y Goshima1, S Nakamura, Y Misu
1Department of Pharmacology, Yokohama City University School of Medicine, Japan.
Abstract:
In rat hypothalamic slices, antagonism by L-DOPA methyl ester and (-)-propranolol against L-DOPA-induced facilitation of endogenous noradrenaline (NA) release was characterized under the inhibition of dopadecarboxylase. L-DOPA at 10 nM to 1 microM facilitated the evoked NA release in a concentration-dependent manner. L-DOPA methyl ester (3, 10 and 30 nM) progressively shifted the concentration-release curve for L-DOPA to the right: Schild plots gave a straight line with a slope of 1.00 and pA2 was 8.9. This antagonistic action was not mimicked by L-phenylalanine, a substrate for L-DOPA transport system. In contrast, 10 and 100 nM propranolol concentration-dependently reduced the maximal effect of L-DOPA without rightward shift of the concentration-release curve. L-DOPA methyl ester is a potent competitive antagonist for the action of L-DOPA, and the recognition site of L-DOPA differs from presynaptic beta-adrenoceptors.
More Related Videos
Related Concept Videos
Hypothalamic-Pituitary Axis
Competition
Facilitated Transport
Facilitated Transport
Agonism and Antagonism: Quantification
To quantify these effects, researchers use a dose-response curve, which provides valuable information about the potency and efficacy of a drug. Potency refers to...
Social Facilitation

