Effect of preemptive local injection of ropivocaine with dexmedetomidine on mirror pain in rats and its mechanism

OBJECTIVE@#To observe the effect of preemptive local injection of ropivocaine with dexmedetomidine on activation of glial cells and on the mirror pain in rats and its mechanism.@*METHODS@#A total of 48 adult male Sprague-Dawley rats (weighing 180 g-220 g) were included in the study and randomized into 3 groups, Group S, Group R, and Group RD1. A rat model of persistent postoperative pain evoked by skin/muscle incision and retraction was established in the three groups. Before procedures and nerve extraction, Group S (n = 16) was injected 0.9% saline locally; Group R (n = 16) was injected 0.5% ropivocaine locally, and Group RD1 (n = 16) was injected 0.5% ropivocaine in combined with 1 μg dexmedetomidine locally. After the model being established in the three groups, 8 rats were used for behavior test until 28 d, and dorsal root ganglions (DRGs) of the other 8 rats were harvested on the 3rd day after surgery. Immunofluorescent and transmission electron microscopy were used to observe the activation of glial cells in DRG, and the behavior test results in the three groups were compared.@*RESULTS@#The results showed that mechanical pain threshold in ipsilateral hind-paws of the Group S, Group R, Group RD1 animals dropped to (3.640 ± 1.963) g, (5.827 ± 1.204) g, (7.482) ± 1.412 g at 3 d respectively; while in contralateral paws dropped to (7.100 ± 1.789) g, (17.687 ± 1.112) g, (16.213 ± 1.345) g on the 3 d respectively. Immunofluorescent showed that the glial cells were activated in bilateral side DRG after surgery in 3 groups, but ipsilateral paws expressed more active glial cells than contralateral paws. Transmission electron microscopy showed that mitochondria swelling/vacuolization and lysosomes were more obvious in ipsilateral paws than contralateral paws, but Group RD1 formula could reduce glial cells activity, mitochondria swelling/vacuolization and the amount of lysosomes.@*CONCLUSIONS@#Local injection of ropivocaine and/or dexmedetomidine can effectively inhibit the activation of glial cells in DRG, mitigate the pathological changes of neuron in DRG and reduce mirror image pain.

Effect of preemptive local injection of ropivocaine with dexmedetomidine on mirror pain in rats and its mechanism

Objective: To observe the effect of preemptive local injection of ropivocaine with dexmedetomidine on activation of glial cells and on the mirror pain in rats and its mechanism. Methods: A total of 48 adult male Sprague-Dawley rats (weighing 180 g-220 g) were included in the study and randomized into 3 groups, Group S, Group R, and Group RD

Effect of aquaporin-4 deficiency on intravenous anaesthetic induced hypnotic effects in mice / 生理学报

The deficiency of aquaporin-4 (AQP4) has been reported to alter release of neurotransmitters in the mouse brain. However, the functional relevance of AQP4 in mediating essential components of the general anaesthetic state is unknown. The aim of the present study was to investigate the role of AQP4 in general anaesthesia in mice lacking AQP4. The hypnotic effects of propofol, ketamine, and pentobarbital in AQP4 knockout (KO) and CD1 control mice were evaluated using the behavioural endpoint of loss of righting reflex (LORR). The effects of propofol on extracellular levels of amino acids in prefrontal cortex of freely moving mice were investigated using microdialysis coupled to high performance liquid chromatography with fluorescent detection. The result showed that, after receiving ketamine or pentobarbital, LORR occurred at earlier time in KO mice than that in control animals. Intraperitoneal injection of ketamine or pentobarbital increased the duration of LORR. After the administration of propofol, the duration of LORR was significantly reduced in KO mice compared with that in controls. Propofol increased the extracellular levels of aspartate, glutamate, and GABA, but not taurine, in prefrontal cortex. There were significant differences of increase patterns of the three kinds of neurotransmitters between KO and WT mice. Notably, the duration of GABA level increase correlated with the duration of LORR in two genotypes of mice. These results provide in vivo evidence of different responses in time-dependent release of excitatory and inhibitory neurotransmitters in prefrontal cortex of the two genotypes of mice. It is suggested that changes in anaesthetic reactions in mice with AQP4 loss may be related to neurotransmitter regulation, and that normal functioning of AQP4 plays an important role in the maintenance of anaesthetic hypnosis.

Measurement of the minimum alveolar concentration of sevoflurane during combined anesthesia with sevoflurane, small-dose dexmedetomidine and fentanyl / 南方医科大学学报

<p><b>OBJECTIVE</b>To determine the minimum alveolar concentration (EC(50) and EC(95)) of sevoflurane in body movement response to surgical incision during combined anesthesia with dexmedetomidine, sevoflurane and fentanyl.</p><p><b>METHODS</b>Twenty-six ASA class I or II patients (aged 18-60 years) underwent selective surgery for lumbar disc herniation under general anesthesia with the combination of with dexmedetomidine, sevoflurane and fentanyl. All the patients received infusion with 0.5 mg/kg dexmedetomidine for 10 min before anesthesia induction with intravenous injection of 3 µg/kg fentanyl 8% sevoflurane inhalation. Upon loss of consciousness, sevoflurane concentration was reduced to 5% with intravenous injection of 1-2 mg/kg succinylcholine, and intubation was started after muscles relaxation. Anesthesia was maintained by sevoflurane and dexmedetomidine (0.2 µg·kg(-1)·h(-1)). Before the surgery, a steady state end-tidal sevoflurane concentration was maintained for at least 10 min. The first patient of the series was tested with 1.5% sevoflurane, and the concentration was adjusted according to modified Dixons up-and-down method (with a step size of 0.2%). Probit analysis was used for calculating EC(50), EC(95) and the 95% confidence interval (CI).</p><p><b>RESULTS</b>The EC(50) of sevoflurane was 0.94% (95%CI of 0.76%-1.07% ) and EC(95) was 1.23% (95%CI 1.09%-2.05% ).</p><p><b>CONCLUSION</b>The EC(50) and EC(95) of sevoflurane are 0.94% and 1.23%, respectively, for suppressing body movement in response to surgical incision during combined anesthesia with sevoflurane, dexmedetomidine and fentanyl.</p>

Protective effects of sufentanil pretreatment against acute gastric mucosal lesion in rats and its relationship with acid-sensing ion channels / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effects of sufentanil pretreatment on acute gastric mucosal lesion and its impact on the expression of acid-sensing ion channel 3 (ASIC3) in thoracic dorsal root ganglia (DRG) neurons in rats with water immersion-restraint stress (WIRS).</p><p><b>METHODS</b>Twenty-four Wistar rats were randomly assigned into 3 groups, namely the normal control group (n=6), WIRS group (n=12) and sufentanil pretreatment group (n=6). Gastric mucosal lesion was induced by WIRS, and after 6 h of WIRS, the gastric tissues were excised and observed under microscope, with the ulcer index (UI) calculated. The expression of ASIC3 in the DRG neurons was detected by immunofluorescence assay, and the ASIC3 mRNA expression by quantitative real-time RT-PCR.</p><p><b>RESULTS</b>Compared with the normal control group, the rats in the WIRS group showed obvious gastric injury with increased UI and extensive expression of ASIC3 in the DRG neurons. Sufentanil pretreatment of the rats subjected to WIRS significantly alleviated the gastric mucosal injury, lowered the UI, and reduced ASIC3 mRNA expression in thoracic DRG neurons.</p><p><b>CONCLUSION</b>ASIC3 is involved in the development of acute gastric mucosal lesion, and sufentanil pretreatment offers protection of gastric mucosa by inhibiting the expression of ASIC3.</p>