Background:

trans-ACPD, a metabotropic receptor agonist, produces calcium mobilization and an inward current in cultured cerebellar Purkinje neurons.
Excitatory amino acid (EAA) analogues activate receptors that are coupled to the increased hydrolysis of phosphoinositides (PIs). In these studies, hippocampal slices are prepared from neonatal rats (6-11 days old) to characterize the effects of EAA analogues on these receptors. The concentrations of trans-ACPD required to evoke half-maximal stimulation (EC50 value) is 51 μM. DL-2-Amino-3-phosphonopropionate (DL-AP3) is also equipotent as an inhibitor of PI hydrolysis stimulated by ibotenate, quisqualate, and trans-ACPD (IC50 values are 480-850 μM)[2].
Intrathecal injection of NMDA, kainate, and trans-ACPD, TNF-α, or IL-1β causes significant (p<0.001) biting behaviour in mice compared to animals injected intrathecally with saline. In all groups, systemic pre-treatment with GM (100 mg/kg, i.p.) significantly (p<0.001) reduces the biting behaviour compared to mice treated with saline (10 mL/kg, i.p.). The greatest effect of GM is observed on the pro-inflammatory cytokines and NMDA, with the following inhibition percentages: TNF-α (92±7%), IL-1β (91±5%), NMDA (69±1%), and trans-ACPD (71±12%). By contrast, at the same dose, GM has no significant effect on the kainate-mediated biting response[3].
Reference:
[1]. Linden DJ, et al. Trans-ACPD, a metabotropic receptor agonist, produces calcium mobilization and an inward current in cultured cerebellar Purkinje neurons. J Neurophysiol. 1994 May;71(5):1992-8.
[2]. Littman L, et al. Multiple mechanisms for inhibition of excitatory amino acid receptors coupled to phosphoinositide hydrolysis. J Neurochem. 1992 Nov;59(5):1893-904.
[3]. Córdova MM, et al. Polysaccharide glucomannan isolated from Heterodermia obscurata attenuates acute and chronic pain in mice. Carbohydr Polym. 2013 Feb 15;92(2):2058-64.