L-Cysteinesulfinic acid monohydrate is a potent agonist at rat metabotropic glutamate receptors (mGluRs) with pEC50s of 3.92, 4.6, 3.9, 2.7, 4.0, and 3.94 for mGluR1, mGluR5, mGluR2, mGluR4, mGluR6, and mGluR8, respectively[1].

L-Cysteinesulfinic acid (monohydrate) serves as an innate activator for the phospholipase D (PLD)-linked metabotropic excitatory amino acids (EAA) receptor, selectively triggering the PLD-associated mechanism. When applied to hippocampal slices, 1 mM concentrations of L-CSA (monohydrate) significantly enhance PLD activity, unlike similar doses of L-glutamate, L-aspartate, and L-HCA, which show no effect. Furthermore, L-CSA (monohydrate) prompts a dose-responsive elevation in PLD activity in these slices, even when iGluR antagonists are present, with the potency around an EC50 of 500 uM. Notably, the response to 1 mM L-CSA (monohydrate) in augmenting PLD activity remains unaltered by 1 uM tetrodotoxin, indicating that the effect is not reliant on an increase in neuronal activity[1].