L-AP4 (L-APB) monohydrate is a potent and specific agonist for group III mGluRs, with EC50s of 0.13, 0.29, 1.0, and 249 μM for mGlu4, mGlu8, mGlu6, and mGlu7 receptors, respectively [1][2].

mGlu6:1.0 μM (EC50), mGlu4:0.13 μM (EC50), mGlu7:249 μM (EC50), mGlu8:0.29 μM (EC50)

Intrathecal injection of L-AP4 (5-30 μg) over 4-5 days notably enhances the paw withdrawal threshold in response to von Frey filament application in eight nerve-ligated rats, demonstrating a dose-dependent effect. This treatment does not lead to any observable motor dysfunction. Furthermore, a specific dose of 30 μg L-AP4 does not significantly change paw withdrawal latency in normal rats. Additionally, the topical application of 5 to 50 μM L-AP4 directly to the spinal cord markedly reduces the neuronal response to sensory stimuli such as touch, pressure, pinch, and von Frey filaments in a concentration-dependent manner. The experiments were conducted using rat models.