An interaction between basolateral amygdala orexinergic and endocannabinoid systems in inducing anti-nociception in the rat formalin test
- 3 August 2022
- journal article
- research article
- Published by Springer Science and Business Media LLC in Psychopharmacology
- Vol. 239 (10), 1-14
- https://doi.org/10.1007/s00213-022-06199-1
Abstract
The amygdala has emerged as the main brain center for the emotional affective dimension of pain and pain modulation. In the amygdala, orexin and cannabinoid receptors are expressed in relatively high concentrations. To investigate the possible interaction between the amygdala orexin and cannabinoid systems on the modulation of inflammatory pain, we conducted formalin, rotarod, and plethysmometer tests, as well as analyzing mRNA expression of orexin and cannabinoid receptors in male rats. The basolateral amygdala (BLA) was unilaterally implanted by a guide cannula. Our results showed that, compared to saline and DMSO/saline, intra-BLA microinjection of orexin-A (50 and 100 µM) decreased flinch response in the early phase, but not in the late phase of the formalin test. However, these injections had no significant effect on the mRNA expression level of BLA, orexin receptor type-1 (Orx1), and cannabinoid receptor type-1 (Cb1). Moreover, intra-BLA administration of Orx1 receptor antagonist (SB-334867; 50 nM) and Cb1 receptor antagonist (AM251; 250 and 500 nM) decreased flinch response only in the early phase of the formalin test as compared to the DMSO group. Although the intra-BLA infusion of orexin-A alone and along with SB-334867 or AM251 decreased flinch response in the early phase of the formalin test, intra-BLA co-microinjection of SB-334867/AM251/OrxA increased flinch response in both early and late phases of the formalin test when compared to the DMSO/OrxA group. Interestingly, in the SB-334867/AM251/OrxA group, the Cb1 receptor was upregulated in all groups in comparison to Orx1 receptors. Our results revealed an interaction between BLA, orexin-A, and Cb1 receptors in inducing anti-nociception in the formalin test.This publication has 52 references indexed in Scilit:
- Endocannabinoid signaling in the amygdala: anatomy, synaptic signaling, behavior, and adaptations to stressNeuroscience, 2012
- Activation of Orexin 1 Receptors in the Periaqueductal Gray of Male Rats Leads to Antinociception via Retrograde Endocannabinoid (2-Arachidonoylglycerol)-Induced DisinhibitionJournal of Neuroscience, 2011
- Cannabinoid Transmission in the Basolateral Amygdala Modulates Fear Memory Formation via Functional Inputs to the Prelimbic CortexJournal of Neuroscience, 2011
- Intra-Periaqueductal Gray Matter Microinjection of Orexin-A Decreases Formalin-Induced Nociceptive Behaviors in Adult Male RatsThe Journal of Pain, 2011
- Comparison of incremental and accelerating protocols of the rotarod test for the assessment of motor deficits in the 6-OHDA modelJournal of Neuroscience Methods, 2006
- Cannabinoid pharmacology: the first 66 yearsBritish Journal of Pharmacology, 2006
- DECONSTRUCTING ENDOGENOUS PAIN MODULATIONSJournal of Neurophysiology, 2005
- Orexin (Hypocretin) Effects on Constitutively Active Inward Rectifier K+ Channels in Cultured Nucleus Basalis NeuronsJournal of Neurophysiology, 2004
- Antiallodynic Effects of Intrathecal Orexins in a Rat Model of Postoperative PainThe Journal of pharmacology and experimental therapeutics, 2003
- Effects of Orexin (Hypocretin) on GIRK ChannelsJournal of Neurophysiology, 2003