1. Anxiolytic effect of GABAergic neurons in the anterior cingulate cortex in a rat model of chronic inflammatory pain.
- Author
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Shao FB, Fang JF, Wang SS, Qiu MT, Xi DN, Jin XM, Liu JG, Shao XM, Shen Z, Liang Y, Fang JQ, and Du JY
- Subjects
- Animals, Anti-Anxiety Agents administration & dosage, Anti-Anxiety Agents pharmacology, Anti-Anxiety Agents therapeutic use, Anxiety drug therapy, Anxiety etiology, Central Nervous System Sensitization drug effects, Chronic Pain psychology, Clozapine therapeutic use, Freund's Adjuvant toxicity, GABA-A Receptor Agonists administration & dosage, GABA-A Receptor Agonists pharmacology, GABA-A Receptor Agonists therapeutic use, GABA-A Receptor Antagonists administration & dosage, GABA-A Receptor Antagonists pharmacology, GABA-A Receptor Antagonists toxicity, GABAergic Neurons enzymology, Genetic Vectors pharmacology, Inflammation chemically induced, Inflammation physiopathology, Injections, Interneurons drug effects, Male, Muscimol administration & dosage, Muscimol pharmacology, Muscimol therapeutic use, Open Field Test, Pain Threshold drug effects, Patch-Clamp Techniques, Picrotoxin toxicity, Presynaptic Terminals drug effects, Presynaptic Terminals physiology, Pyramidal Cells enzymology, Rats, Rats, Sprague-Dawley, Anxiety physiopathology, Chronic Pain physiopathology, GABAergic Neurons physiology, Gyrus Cinguli physiopathology, Inflammation psychology, Pyramidal Cells physiology
- Abstract
Chronic pain easily leads to concomitant mood disorders, and the excitability of anterior cingulate cortex (ACC) pyramidal neurons (PNs) is involved in chronic pain-related anxiety. However, the mechanism by which PNs regulate pain-related anxiety is still unknown. The GABAergic system plays an important role in modulating neuronal activity. In this paper, we aimed to study how the GABAergic system participates in regulating the excitability of ACC PNs, consequently affecting chronic inflammatory pain-related anxiety. A rat model of CFA-induced chronic inflammatory pain displayed anxiety-like behaviors, increased the excitability of ACC PNs, and reduced inhibitory presynaptic transmission; however, the number of GAD65/67 was not altered. Interestingly, intra-ACC injection of the GABA
A R agonist muscimol relieved anxiety-like behaviors but had no effect on chronic inflammatory pain. Intra-ACC injection of the GABAA R antagonist picrotoxin induced anxiety-like behaviors but had no effect on pain in normal rats. Notably, chemogenetic activation of GABAergic neurons in the ACC alleviated chronic inflammatory pain and pain-induced anxiety-like behaviors, enhanced inhibitory presynaptic transmission, and reduced the excitability of ACC PNs. Chemogenetic inhibition of GABAergic neurons in the ACC led to pain-induced anxiety-like behaviors, reduced inhibitory presynaptic transmission, and enhanced the excitability of ACC PNs but had no effect on pain in normal rats. We demonstrate that the GABAergic system mediates a reduction in inhibitory presynaptic transmission in the ACC, which leads to enhanced excitability of pyramidal neurons in the ACC and is associated with chronic inflammatory pain-related anxiety., (© 2021. The Author(s).)- Published
- 2021
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