| Description |
trans-ACPD, a metabotropic receptor agonist, produces calcium mobilization and an inward current in cultured cerebellar Purkinje neurons.
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| Related Catalog |
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| Target |
Calcium Channel[1]
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| In Vitro |
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].
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| In Vivo |
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].
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| Animal Admin |
Mice[3] Male Swiss mice (25-35 g) are used. Intrathecal injections are given to fully conscious mice. Briefly, the animals are manually restrained, and a 30-gauge needle connected by a polyethylene tube to a 25 μL Hamilton gas-tight syringe is inserted through the skin and between the vertebrae into the subdural space of the L5-L6 spinal segments. Intrathecal injections (5 μL/site) are administered over a period of 5 s. Biting behaviour is defined as a single head movement directed at the flanks or hind limbs, resulting in contact of the animal's snout with the target organ. The nociceptive response is elicited by NMDA (450 pmol/site, a selective agonist of the NMDA glutamatergic ionotropic receptor), kainate (110 pmol/site, a selective agonist of the kainate subtype of glutamatergic ionotropic receptors), and trans-ACPD (50 nmol/site, a non-selective agonist of metabotropic glutamate receptors, which is active at group I and group II), TNF-α (0.1 pmol/site) and IL-1β (1 pmol/site) or saline (5 μL/site, i.t.). The amount of time the animal spent biting or licking the caudal region is taken as evidence of nociception and is evaluated following local post injections of the following agonists: NMDA (5 min), kainate (4 min), and trans-ACPD TNF-α, and IL-1β (15 min). Animals received GM (100 mg/kg, i.p.) 0.5 h before intrathecal injection of 5 μL of the drugs, while control animals received a similar volume of saline (10 mL/kg, i.p.).
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| References |
[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.
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