- 作者: Yeong-Ray Wen; Chia-Chuan Wang; Geng-Chang Yeh; Sheng-Feng Hsu; Yung-Jen Huang; Yen-Li Li; Wei-Zen Sun
- 作者服務機構: Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, R.O.C.
- 中文摘要: --
- 英文摘要:
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 2-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 μl of 5% formalin produced noxious
behaviors with cumulative pain scores similar to those of 50 μl 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 latencies indicating a
DNIC response. However, the electrical stimulation-induced DNIC was reversed by
yohimbine, but not by naloxone; whereas noxious formalin-induced analgesia was both
naloxone- and yohimbine-reversible.
Conclusions: It is demonstrated that DNIC produced by different types of conditioning
stimuli can be mediated by different descending inhibitory controls, indicating the
organization within the central nervous circuit is complex and possibly exhibits
particular clinical manifestations. - 中文關鍵字: --
- 英文關鍵字: --