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UNLABELLED To examine whether the gamma-aminobutyric acid (GABA) receptor agonists and L-type voltage-dependent calcium channel blockers potentiate each other on the visceral antinociceptive effects at the spinal cord, we assessed visceral nociception with colorectal distension (CD) test in rats with an intrathecal catheter. The measurements were performed(More)
UNLABELLED Previous reports indicate that there may be an interaction between gamma-aminobutyric acid receptors and opioid receptors systems within the spinal cord, the antinociceptive effects of which have not been elucidated. We examined the effects of intrathecally coadministered morphine and muscimol or baclofen on somatic and visceral antinociception(More)
BACKGROUND Morphine can desensitize mu-opioid receptor (MOR), but it does not cause internalization of the receptor after binding. Acute desensitization of MOR impairs the efficiency of signaling, whereas the receptor internalization restores the cell responsiveness to the agonists. Thereby, the property of morphine may limit the analgesic effects of this(More)
BACKGROUND The current study investigated whether racemic bupivacaine and its S(-)- and R(+)-enantiomers, levobupivacaine and dextrobupivacaine, differ in somatic and visceral antinociception and neurotoxicity when administered intrathecally in rats. METHODS In experiment 1, rats intrathecally received 15 microl saline or 0.125, 0.25, 0.5, or 1%(More)
UNLABELLED There is a considerable difference in the number of reports of neurologic injury in the literature between lidocaine and other local anesthetics. Few in vivo animal studies have produced convincing results showing a difference in neurotoxicity among anesthetics. We investigated whether lidocaine and bupivacaine differ with respect to sensory(More)
BACKGROUND Clinically, epidural coadministration of opioids and local anesthetics has provided excellent analgesia for various types of pain. However, information about the interaction of these drugs when administered epidurally is limited. Therefore, we evaluated the antinociceptive interaction between morphine and lidocaine on both somatic and visceral(More)
The existence of prostaglandin (PG) receptors in the spinal cord has been demonstrated, but their role in sensory processing is not yet well defined. PGE1 is widely used clinically as a vasodilator. The present study was designed to investigate the effects of intrathecally administered PGE1 on the transmission of different types to sensory information,(More)
UNLABELLED This study was designed to investigate the effects of ketamine, an N-methyl-D-aspartate receptor antagonist, on the development of tolerance to morphine and morphine antinociception during intrathecal infusion. Two intrathecal catheters were implanted in the subarachnoid space in male rats under pentobarbital anesthesia. One catheter was used for(More)
The combination of ketamine and xylazine is a widely used anesthetic for laboratory animals. However, due to an abuse problem in Japan, ketamine has been specified as a narcotic since 2007. Instead of using ketamine, Kawai et al. reported an injectable formula with an equivalent effect to the mixture of ketamine and xylazine [11]. The mixture of 0.3 mg/kg(More)
BACKGROUND Although there is a considerable difference in the number of clinical reports of neurologic injury between spinal anesthesia and other regional techniques, there are no animal data concerning a difference in the local anesthetic neurotoxicity between intrathecal and epidural administration. In the current study, the functional and morphologic(More)