Selective Interactions of Valeriana officinalis Extracts and Valerenic Acid with [3H]Glutamate Binding to Rat Synaptic Membranes
Figure 3
Interactions of valerian extracts, valerenic acid, and isoborneol on metabotropic glutamate receptors (mGluR). (a) At lower concentrations of valerian extract (0.05 mg/mL) in presence of LCCG-I, a Group II metabotropic glutamate receptor agonist, there was a marked decrease in the binding. This effect was not seen with QA and L-AP4. Valerian extracts at 10 mg/mL, in presence of both QA and LCCG-I, significantly decreased the glutamate binding. ((a)-Insert) A marked decrease in the [3H]Glutamate binding was observed when valerian extracts (0.001 mg/mL) were in the presence of DCG-IV and EGLU, a Group II metabotropic glutamate receptor agonist and antagonist, respectively. (b) Valerenic acid concentration at 0.008 mg/mL, in the presence of QA, a Group I metabotropic glutamate receptor agonist, produced a significant increase in the binding. No effects were observed in presence of DCG-IV, LCCG-I, EGLU, and L-AP4. (c) Isoborneol, at 0.0008 and 1 mg/mL increased [3H]Glutamate binding by 49% and 64%, respectively. Isoborneol in the presence of mGluR ligands, indiscriminately interacted with all of them. At 0.0008 mg/mL, isoborneol interacted with QA and markedly decreased (14%) [3H]Glutamate binding. In addition, isoborneol interacted with all the mGluR agonists (LCCG-I, DCG-IV, and spaglumic) and antagonist (EGLU). Isoborneol also strongly interacted with L-AP4 at both concentrations (0.0008 mg/mL and 1 mg/mL) and resulted in an increased [3H]Glutamate binding (37% and 46%, resp.). + agonist versus agonist + (valerian, valerenic acid, or isoborneol), .
