The Visceral Anticiceptive Mechanism Of Propofol In Spinal Cord In Rats

Background and Objective:Propofol is the most common clinical intravenous anesthetics. A large number of animal experimental and clinical studies have shown that propofol for pain caused by hurt stimulation has analgesic action. There is evidence that spinal cord exist propofol sites, but the important role of regulation of participation in damage information is unclear. Spinal cord accept peripheral feeling signal and the signal of the processes by uploading local inhibitory neurons tension suppression, this inhibition partly by inhibiting the amino acids—r-amino butyric acid (GABA) and glycine (glycine, Gly) mediated. GABA is a kind of important inhibitory neurotransmitter that distributed in central nervous system in mammals, GABA receptors alone with endogenous ligand—r-amino combining butyrate produce inhibitory postsynaptic potential (inhibitory postsynaptic potention IPSP). GABA receptors is regulated by at least two receptor subtypes—GABAA and GABAB. GABAA receptor is GABA receptors alone in the family type gating channel receptors, GABAA receptor is enabled produce rapid type inhibitory postsynaptic potential (fast IPSP). GABAA receptor is one of the most important sites of the propofol. In 1973, opioid receptors was reported and extracted successively by six laboratory in Britain and Sweden. Brain endorphins,anuria peptides,strong brown peptide, and other opioid sample function material were subsequently discovered. They are a kind of morphine or opium kind of endogenous activity material, and in the chemical structure they belong to the peptide,so they are called endogenous opioid peptides. GABA and endogenous opioid peptides are two principal inhibitory neurotransmitter in central nervous system, they play inhibition by combining the corresponding receptor in spinal cord supraspinal structures after tail amputation.So propofol whether can resist damage function in spinal cord level? The mechanism of its action?Therefore, this experiment use scabbard dosing method, using a new type of visceral pain animal model that formalin injected by the rectum submucosal, we use the method of ethology and morphology in spinal cord level to explore anti visceral injury mechanism of propofol and it is involved in the GABAA receptor and opioid receptors? The study of anesthetic drugs enrichs the understanding of mechanisms of general anesthesia, and provides theory basis for using propofol In clinical.Methods:1. Behavioral research methods:56 adult female SD rats were successfully embedded catheter in the spinal cord subarachnoid and randomly divided into 7 groups (n=8). Group ND:normal saline and dimethyl sulfoxide group, group P1: propofol group of lOug, group P2:propofol group of 20ug Group B:Bicuculline control; group BP1:Bicuculline making group, (Nal) control; Naloxone, NaP1group: Naloxone making group. In sevoflurane anesthesia formalin was injected in the rectum submucosal that copied visceral pain animal models, after waking we inject each drug group in the scabbard and watch rats of behaviouristics changes, and every 15min we make a visceral pain score within 1h.2. Morphology research methods:behavior observed after 1 hour,we take L2-3 segments of spinal cord and with immunohistochemical method observe c-fos expression of spinal cord supraspinal structures after tail amputation of each rat and program sample neurons Fos immune response(FOS-like immunoreactivity,FLI) positive cell count.Statistics: All data to mean±standard deviation (x±s) that the application of SPSS 11.5 software to analyze the data, we use single factor analysis of variance (ANOVA) to process by behaviorism and use variance analysis of t-test between groups by morphology,ρ<0.05 is statistically thought to be different significantly.Results:1. Behavioral research results:visceral pain score of the rats of group ND gets to maximum after 30min injecting formalin, after 45min to 60min injecting formalin visceral pain score gradually reduced.within 60min compared with group ND, visceral pain score of the rats of group B and group Na is not apparent change (ρ>0.05), visceral pain score of the rats of group P1 and P2 is significantly lower (ρ< 0.05), the difference was statistically significant,and the difference between the rats of group P1 and P2 is not statistically significant (ρ>0.05). compared with Group P1, visceral pain score the rats of Group BP1 and NaP1 is increased (p< 0.05), the difference is statistically significant; Compared with the rats of group B, visceral pain score is lower than the rats of group BP1 (ρ< 0.05), the difference is statistically significant; compared with groupNa, visceral pain score is lower than group NaP1 (ρ<0.05), the difference was statistically significant.2. Morphology research results:spinal cord supraspinal structures after tail amputation the rats of group ND exit amounts of FLI positive cells. compared with Group ND, FLI positive cells in spinal cord supraspinal structures after tail amputation of the rats of group B and Na are not change (p>0.05), FLI positive cells in spinal cord supraspinal structures after tail amputation of the rats of group P1 and P2 are significantly reduced (p<0.05), the difference is statistically significant, and FLI positive cells in spinal cord supraspinal structures after tail amputation of group P1 and P2 are not changce, the difference between group P1 and P2 is not statistically significant (p>0.05). compared with Group P1, FLI positive cells in spinal cord supraspinal structures after tail amputation of group BP1 and NaP1 are increased (p< 0.05), the difference was statistically significant; compared with Group B, FLI positive cells in spinal cord supraspinal structures after tail amputation of group BP1 are reduced (p<0.05), the difference is statistically significant; compared with Na. FLI positive cells in spinal cord supraspinal structures after tail amputation of group NaP1 are reduced (p<0.05), the difference is statistically significant.Conclusion:1.proPofol has antinociceptive effect on visceral nociception induced by formalin.2. The visceral antinociceptive mechanism of propoofol is in relation to GABAA receptor at spinal level.3. The visceral antinociceptive mechanism of propoofol is in relation to opioid receptor at spinal level.