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Differential Role of Central GABA Receptors in Nociception of Orofacial Area in Rats KCI 등재후보
- 언어KOR
- URLhttps://db.koreascholar.com/Article/Detail/306627
The present study investigated the role of central GABAA and GABAB receptors in orofacial pain in rats. Experiments were conducted on Sprague-Dawley rats weighing between 230 and 280 g. Intracisternal catheterization was performed for intracisternal injection, under ketamine anesthesia. Complete Freund's Adjuvant (CFA)-induced thermal hyperalgesia and inferior alveolar nerve injury-induced mechanical allodynia were employed as orofacial pain models. Intracisternal administration of bicuculline, a GABAA receptor antagonist, produced mechanical allodynia in naive rats, but not thermal hyperalgesia. However, CGP35348, a GABAB receptor antagonist, did not show any pain behavior in naive rats. Intracisternal administration of muscimol, a GABAA receptor agonist, attenuated the thermal hyperalgesia and mechanical allodynia in rats with CFA treatment and inferior alveolar nerve injury, respectively. On the contrary, intracisternal administration of bicuculline also attenuated the mechanical allodynia in rats with inferior alveolar nerve injury. Intracisternal administration of baclofen, a GABAB receptor agonist, attenuated the thermal hyperalgesia and mechanical allodynia in rats with CFA treatment and inferior alveolar nerve injury, respectively. In contrast to GABAA receptor antagonist, intracisternal administration of CGP35348 did not affect either the thermal hyperalgesia or mechanical allodynia. Our current findings suggest that the GABAA receptor, but not the GABAB receptor, participates in pain processing under normal conditions. Intracisternal administration of GABAA receptor antagonist, but not GABAB receptor antagonist, produces paradoxical antinociception under pain conditions. These results suggest that central GABA has differential roles in the processing of orofacial pain, and the blockade of GABAA receptor provides new therapeutic targets for the treatment of chronic pain.
