ABSTRACT
BACKGROUND: Chronic pain is characterized as high morbidity, long course and poor curative efficacy, and the underlying mechanism still remains unclear. The research on analgesics and analgesic mechanisms is an issue of concern. OBJECTIVE: To explore the effect of angiotensin Ⅱ receptor antagonists EMA401 on the mechanical withdrawal threshold in a rat model of sciatic nerve constriction-induced neuropathic pain and the underlying mechanisms. METHODS: Sprague-Dawley rats were randomized into five groups: the rat sciatic nerve was exposed without ligation (sham group), and NaCl solution was given via gastric lavage;the model of sciatic nerve constriction was established in the remaining rats,followed by treatment with 2,5 and 10 mg/kg EMA401,and NaCl solutions(model group)via gastric lavage,respectively.As a behavioral indicator,mechanical withdrawal threshold was detected at 1 preoperative day, 3, 7 and 14 postoperative days. Subsequently, the spinal dorsal root ganglion was removed, and the expression levels of glial fibrillary acidic protein, brain-derived neurotrophic factor and activating transcription factor 3 were detected by western blot assay. RESULTS AND CONCLUSION: Compared with the model group, EMA401 significantly improved the mechanical withdrawal threshold of the rats with sciatic nerve constriction (P < 0.05). Moreover, EMA401 significantly upregulated the expression levels of glial fibrillary acidic protein, brain-derived neurotrophic factor and activating transcription factor 3 in the dorsal root ganglion (P < 0.05); the expression levels in the 5 and 10 mg/kg EMA401 groups were significantly lower than those in the 2 mg/kg EMA401 group at 3, 7 and 14 days postoperatively (P < 0.05). These findings implicate that EMA401 exerts obvious analgesic effect on the rat model of sciatic nerve constriction,which may be via inhibiting astrocyte activation in the spinal dorsal root ganglion, downregulating the expression level of brain-derived neurotrophic factor, and further inhibiting the dorsal root ganglion neuron activation that appears with an increase in activated transcription factor 3 expression.
ABSTRACT
<p><b>OBJECTIVE</b>To establish a digital model allowing three-dimensional visualization of the structures involved in the anterior cervical segment approach.</p><p><b>METHODS</b>Based on the imaging data obtained from CT angiography (CTA), magnetic resonance myelography (MRM) and continuous magnetic resonance imaging (MRI) of a healthy volunteer (scanning from the center of the head to the inferior border of the T3 level), image segmentation and reconstruction for the skeleton, arteries, veins, and spinal cord was conducted semi-automatically using the Mimics software according to the different thresholds of the tissues. The cervical plexus, brachial plexus and muscles of the neck were reconstructed with the Nerves pipe editor and the Med CAD module to establishing the three-dimensional model for displaying the structures involved in the anterior cervical segment approach.</p><p><b>RESULTS</b>A three-dimensional digital model of the structures involved in the anterior cervical segment anterior approach was established, which allowed the display of anatomical relations of the skeletal structure, aorta, superior vena cava, thyroid gland, hyoid bone, laryngeal cartilages, trachea, lung, 12 neck muscle groups, as well as the spinal cord, spinal nerves, cervical plexus, brachial plexus, and intervertebral disk of the neck.</p><p><b>CONCLUSION</b>The three-dimensional model established can allow the visualization of the important structures for the anterior cervical segment approach, and provides a medical teaching platform for anatomy and surgical training.</p>