The aim of the present study was to develop an animal model for evaluation of temporomandibular (TMJ) nociception under TMJ inflammation. We also investigated the participation of IL-1β in inflammation-induced TMJ nociception. Experiments were carried out using male Sprague-Dawley rats. Intra-articular injection of 3% formalin was administered to evaluate hyperalgesia 3 days after CFA injection. Intra-articular injection of 3% formalin did not produce nociceptive behavior in normal rats. Although intra-articular injection of 3 doses of CFA produced TMJ inflammation, only 1:3 diluted CFA produced hyperalgesia when formalin was injected intra-articularly 3 days after CFA injection. Co-administration of IL-1 receptor inhibitor with formalin into the TMJ cavity 3 days after CFA injection was performed. Co-administration of IL-1 receptor inhibitor significantly inhibited formalin-induced hyperalgesia in rats with CFA-induced TMJ inflammation. These results suggested that intra-articular injection of formalin produced hyperalgesia under chronic TMJ inflammation. Moreover, IL-1β plays an important role in TMJ hyperalgesia under chronic inflammation and blockade of IL-1β is a potential therapeutic target for inflammatory TMJ pain.

The activation of glial cells in the spinal cord has been contribute to the initiation and maintenance of pain facilitation induced by peripheral inflammation and nerve injury. The present study investigated effects of botulinum toxin type A (BoNT-A), injected subcutaneously or intracisternally, on the expression of microglia and astrocytes in rats. Complete Freund’s Adjuvant (CFA)-induced inflammation was employed as an orofacial chronic inflammatory pain model. A subcutaneous injection of 40 μL CFA into the vibrissa pad was performed under 3% isoflurane anesthesia in SD rats. Immunohistochemical analysis for changes in Iba1 (a microglia marker) and GFAP (an astrocyte marker), were performed 5 days after CFA injection. Subcutaneous injection of CFA produced increases in Iba1 and GFAP expression, in the ipsilateral superficial lamia I and II in the medullary dorsal horn of rats. Subcutaneous treatment with BoNT-A attenuated the up-regulation of Iba1 and GFAP expressions induced by CFA injection. Moreover, intracisternal injection of BoNT-A also attenuated the up-regulated Iba1 and GFAP expressions. These results suggest that the anti-nociceptive action of BoNT-A is mediated by modulation activation of glial cells, including microglia and astrocyte.

이상의 실험결과들을 요약하면, CFA를 안면영역 피하로 주입하여 발생한 염증성 통증 행위반응은 P2X 수용체의 억제제의 투여로 감소할 수 있었다. 특히 P2X7 수용체 억제제를 투여하면 진통작용 뿐 아니라 활성화된 신경아교세포 발현을 억제하였다. 이러한 실험 결과는 P2X7 수용체가 신경아교세포에 영향을 미쳐 안면에서 발생하는 만성 염증성 통증의 발생과 유지에 관여하고 있다는 것을 보여준다. 따라서 중추신경계의 신경아교세포를 조절할 수 있는 중추성 P2X7 수용체 작용기전은 임상에서 만성 염증성 통증을 보다 효과적으로 치료할 수 있는 새로운 방법을 제시해 줄 수 있다고 생각된다.

The power spectrum of the galaxy distribution is accurately measured up to wavelengths over 100h−1 100h−1 Mpc from the CfA 1 and 2 catalogs. We find that our results agree with power spectra calculated by others from smaller samples of optical, radio and infrared galaxies. The power spectrum of an open CDM model (Ωh Ωh = 0.2 and δ8 δ8 = 1; see below for definitions) best approximates the observed power spectrum. The power spectrum of the standard COM model (Ωh Ωh = 0.5 and δ8 δ8 = 1) is inconsistent with the observed one at the 99% confidence level. Our best estimation of the corresponding correlation function in real space is ξ(r)=(r/6.2h−1Mpc)−1.8 ξ(r)=(r/6.2h−1Mpc)−1.8 for r < 20h−1 20h−1 Mpc.