TAILIEUCHUNG - DNIC-mediated analgesia produced by a supramaximal electrical or a high-dose formalin conditioning stimulus: roles of opioid and a2-adrenergic receptors

Diffuse noxious inhibitory controls (DNIC) can be produced by different types of conditioning stimuli, but the analgesic properties and underlying mechanisms remain unclear. The aim of this study was to differentiate the induction of DNIC analgesia between noxious electrical and inflammatory conditioning stimuli. Methods: First, rats subjected to either a supramaximal electrical stimulation or an injection of high-dose formalin in the hind limb were identified to have pain responses with behavioral evidence and spinal Fos-immunoreactive profiles. Second, suppression of tail-flick. | Wen et al. Journal of Biomedical Science 2010 17 19 http content 17 1 19 The cost of publication in Journal of Biomedical Science Is borne by the National Science Council Taiwan JOURNAL OF BIOMEDICAL SCIENCE RESEARCH Open Access DNIC-mediated analgesia produced by a supramaximal electrical or a high-dose formalin conditioning stimulus roles of opioid and a2-adrenergic receptors 7 U z-i D -s A X 1 2 3 Pk I Pl I n n A st k z i4 ỉ . p k x z i f p 1 c p ỉ . c f k x z i I_I r I 15 1 I I f-i V i I_11 I z i 3 ft Il I i3 Yeong-Kay Wen Chia-Chuan Wang Geng-Chang Yeh Sheng-Feng Hsu Yung-Jen Huang Yen-Li LI Wei-Zen Sun6 Abstract Background Diffuse noxious inhibitory controls DNIC can be produced by different types of conditioning stimuli but the analgesic properties and underlying mechanisms remain unclear. The aim of this study was to differentiate the induction of DNIC analgesia between noxious electrical and inflammatory conditioning stimuli. Methods First rats subjected to either a supramaximal electrical stimulation or an injection of high-dose formalin in the hind limb were identified to have pain responses with behavioral evidence and spinal Fos-immunoreactive profiles. Second suppression of tail-flick latencies by the two noxious stimuli was assessed to confirm the presence of DNIC. Third an opioid receptor antagonist naloxone and an a2-adrenoreceptor antagonist yohimbine were injected intraperitoneally and intrathecally respectively before conditioning noxious stimuli to test the involvement of descending inhibitory pathways in DNIC-mediated analgesia. Results An intramuscular injection of 100 pl of 5 formalin produced noxious behaviors with cumulative pain scores similar to those of 50 pl of 2 formalin in the paw. Both electrical and chemical stimulation significantly increased Fos expression in the superficial dorsal horns but possessed characteristic distribution patterns individually. Both conditioning stimuli prolonged the tail-flick .

• Báo cáo khoa học
• statements and documents scientific reports
• medical reports
• medical knowledge
• medical research
• medical research
• health care
• presentation reports
• physical reports
• reports agronomy
• biotechnology
• plants Vietnam
• specialized biological
• clinical trials
• medical management