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Central sensitization is a crucial mechanism underlying the increased excitability of nociceptive pathways following peripheral tissue injury and inflammation. We have previously demonstrated that the small-fiber excitant and inflammatory irritant mustard oil (MO) applied to the tooth pulp produces glutamatergic- and purinergic-dependent central(More)
Central sensitization represents a sustained hypersensitive state of dorsal horn nociceptive neurons that can be evoked by peripheral inflammation or injury to nerves and tissues. It reflects neuroplastic changes such as increases in neuronal spontaneous activity, receptive field size, and responses to suprathreshold stimuli and a decrease in activation(More)
Immunocytochemical technique was used to compare the content of substance P (SP), Met-enkephalin (Met-Enk) and neurotensin (NT) on two sides of the lumbar dorsal horn of rats in which the unilateral dorsolateral funiculus was transected while formalin (0.2 ml, 5%) was injected equally into two hindpaws. The results showed that the SP-like immunoreactivity(More)
We have recently demonstrated that application of mustard oil (MO), a small-fiber excitant and inflammatory irritant, to the rat maxillary molar tooth pulp induces central sensitization that is reflected in changes in spontaneous activity, mechanoreceptive field (RF) size, mechanical activation threshold, and responses to graded mechanical stimuli applied(More)
The effects of intrathecally administered naloxone or aminophylline on the antinociception produced by intrathecal NE, 5-HT, morphine or adenosine receptor agonist, 5'-N-ethylcarboxamidoadenosine (NECA) were observed in rats using the tail-flick test. The results show that: (1) the antinociception produced by NE with doses of 0.5 or 1.0 nmol could be(More)
The effects of intrathecally (IT) administered naloxone (Nal) on the antinociception produced by IT norepinephrine (NE), serotonin (5-HT), or morphine (Mor) were observed and compared in rats using the tail-flick (TF) assay. The results show that: a) NE, 5-HT, and Mor in doses of 1 nmol, 240 nmol, and 0.5 nmol, respectively, produce similar increases in(More)
Our previous studies have demonstrated that application of the inflammatory irritant mustard oil (MO) to the tooth pulp produces trigeminal central sensitization that includes increases in mechanoreceptive field size and responses to noxious stimuli and decrease in activation threshold in brainstem nociceptive neurons of trigeminal subnucleus caudalis (the(More)
The interactions between different doses of serotonin (5-HT) and norepinephrine (NE) in in vivo experiments on rat spinal cord dorsal horn cells was investigated using the integrated electromyography (EMG) measurement of the nociceptive hindlimb flexor reflex (FR). The results indicate that (1) intrathecal (IT) administration of low doses of 5-HT (60 nmol)(More)
The present study was designed to investigate the roles of different subtypes of opioid receptors in ventrolateral orbital cortex (VLO) opioid-evoked antinociception in formalin test by using an automatic detection system for recording the nociceptive behavior (agitation) and a manual method for detecting the duration of licking the injected paw in the(More)