Investigation Of The Relationship Between 5-Hydroxytryptamine And Pain Perception

Pain is one of the most common symptoms in clinical work, often bring great suffering to patients. Harmful damage is the main reasons for cause pain, peripheral nerve damage and tissue damage can lead to pain. The present study shows that, The mechanism of pain mainly divided into the following two kinds:the first one, the incoming ceaselessly for the peripheral nociceptive information; the second one, sensory neurons in the spinal cord changed excitability.5-hydroxytryptamine (5-HT) is evenly distributed in the body of the central nervous system and peripheral nervous system. In peripheral nervous system,5-HT mainly came from source of mast cells and platelets, According to the antagonist specific selectivity of different agonists,5-HT receptor can be divided into the following 7 kinds of types: S-HT1,5-HT2,5-HT3,5-HT4,5-HT5,5-HT6 and 5-HT7 receptor; At the same time, according to the 7 subtypes and its molecular structure of different, and it can be subdivided into 14 different subtypes. According to the current studies, 5-hydroxytryptamine,5-hydroxytryptamine receptors and 5-hydroxytryptamine transporter all has close relationship with pathologic neuralgia.The perception of pain varies from person to person, and many factors involve in the pain experience after noxious stimuli.25-60% of the variance in experimental pain induced by nociceptive stimuli is related to genetically profiles [2,3]. Moreover, previous data show that genetic variation may also contribute to development and progression of long lasting pain conditions.This experiment is divided into two parts:Part Ⅰ:5-HTT SS Genotype is Associated with the Pro-nociceptive Sensation by Alcoholic Sting; Part Ⅱ:Effect of Tetrahydropalmatine on expression of 5-hydroxytryptamine,5-hydroxytryptamine receptors and 5-hydroxytryptamine transporter in spinal dorsal horn(SCDH) of rats with formalin caused pain. PART Ⅰ:The purpose of this study was to examine the relationship between the genetic polymorphism in the promoter of the SLC6A4 gene encoding the serotonin transporter (5-HTT) and the sensitivity to noxious stimulation from a clinical perspective. The genotyping of the 217 outpatients with mild epidermal abrasion in lateral crural region was performed by a combination of polymerase chain reaction(PCR) and digestion. The intensity of pain to medical alcohol treatment was rated on a visual analog scale (VAS). PART Ⅱ:Through method of formalin injection into foot to establish the rat model with formalin a foot pain, and carries on the behavioral observation by shrink the legs and lick the claw time as behavioral response and the c-Fos protein expression in spinal cord posterior horn to judge the formalin pain model successful. Then, the morphological identification of 5-HT,5 HTTP,5H-2A was taken by immunohistochemical method in L4-L5 lumbar spinal cord posterior horn, at the same time, amount of the expression of several substances of appeal was tested by the method of using Western-blot. Discussed in the process of by formalin a foot pain caused by the relationship between the three substances above and pain. Explored and behavioral results pain and as time changes and the change of the above four on the expression of the relationship by determination of c-Fos,5-HT,5-HT2A and 5-HTT in different time periods.RESULTS: PARTⅠ:1. Distribution of 5-HTT Genotype GroupsA total of 217 subjects were recruited in the present experiment, including 61 men and 156 women. According to the results of genotyping,61 of these subjects were determined as low 5-HTT transcription group, with men accounting for 36.06%, and women accounting for 63.93%.86 subjects were determined as medium-5-HTT transcription group, with men accounting for 18.60% and women accounting for 81.40%.70 subjects were determined as High 5-HTT transcription group, with men accounting for 32.86%, and women accounting for 67.14%. The percentages of low-, medium-and high-5-HTT transcription groups were about 28.11,39.63, and 32.25%, respectively;2. Baseline of VAS RatingThe VAS of sterile physiological saline solution treatment was used as baseline of VAS rating. Although the mean of VAS raw score in 5-HTT low expression group is higher than that of the other two groups, there is no statistically significant difference among them The result showed that the artificial treatment with sterile physiological saline solution had no obvious influence on the VAS rating and all subjects were not sensitive to sterile physiological saline solution. Moreover, no significant sex difference was observed in each group following treatment with sterile physiological saline solution.3. Sensitivity Depending on 5-HTT GenotypeBased on the results of normalized VAS ratings, these 5-HTT genotypes had a significant difference on the sensitivity to alcoholic sting. Compared with subjects with high and medium expressions of 5-HTT, the subjects with a genotype coding for low expression had a stronger response to alcoholic sting. No statistically significant effect of alcoholic sting was seen between the medium-and high-5-HTT expression genotype groups. In each group, there were no statistically significant sex differences in the normalized VAS ratings following treatment with medical alcohol.PART Ⅱ:1. Effect of Tetrahydropalmatine on behaviors of rats with formalin foot painThrough experimental results statistics found that rats foot after an injection of formalin, the shrinkage legs licking claws reaction injection presents obviously two time periods, first time for the first 5 minutes after injection in rats began to lick the claw reaction, but in the second five minutes lick claw reaction decreased obviously, and the third after 5 minutes of rat licking PAWS reaction continuously until the end. In addition, compared with formalin model group ibuprofen group rats and tetrahydropalmatine (High, Medium and Low) rat paw licking of shrinkage leg time decreased significantly (p<0.05, n=6).2. The changes of c-Fos protein,5-HT,5-HT2A receptor and 5-HTT in spinal cord of formalin rats with timeThe c-Fos protein,5-HT,5-HT2A receptor and 5-HTT expressed after injection of formalin 30,60,90min.But amount of c-Fos protein,5-HT,5-HT2A receptor and 5-HTT expression was highest in 60min.3.Effect of Tetrahydropalmatine on c-Fos protein expressed in spinal cord of rats with formalin foot painAfter the injection of formalin 60min, L4-L5 lumbar spinal dorsal horn of the c-Fos protein was tested and found that in model group, the amount of c-Fos expression are significantly higher than normal rats (P< 0.05, n=6); The ibuprofen group rats and tetrahydropalmatine (large, medium and small) amount of c-Fos expression in rats are significantly lower than the model group (P< 0.05, n=6).4.Effect of Tetrahydropalmatine on 5-HT expressed in spinal cord of rats with formalin foot painAfter the injection of formalin 60min, L4-L5 lumbar spinal dorsal horn of the 5-HT was tested and found that in model group, the amount of 5-HT expression are significantly higher than normal rats (P< 0.05, n=6); The ibuprofen group rats and tetrahydropalmatine (large, medium and small) amount of 5-HT expression in rats are significantly lower than the model group (P< 0.05, n= 6).5.Effect of Tetrahydropalmatine on 5-HT2A receptor expressed in spinal cord of rats with formalin foot painAfter the injection of formalin 60min, L4L5 lumbar spinal dorsal horn of 5-HT2A receptor was tested and found that in model group, the amount of 5-HT2A receptor expression are significantly higher than normal rats (P< 0.05, n=6); The ibuprofen group rats and tetrahydropalmatine (large, medium and small) amount of5-HT2A receptor expression in rats are significantly lower than the model group (P< 0.05, n=6).6.Effect of Tetrahydropalmatine on 5-HTT expressed in spinal cord of rats with formalin foot painAfter the injection of formalin 60min, L4-L5 lumbar spinal dorsal horn of the 5-HTT was tested and found that in model group, the amount of 5-HTT expression are significantly higher than normal rats (P< 0.05, n=6); The ibuprofen group rats and tetrahydropalmatine (large, medium and small) amount of 5-HTT expression in rats are significantly lower than the model group (P< 0.05, n=6).CONCLUSION:1. The pain sensitivity may have a connection with 5-HTT related genes type.2. Formalin pain model induced L4-L5 lumbar spinal cord posterior horn Fos,5-HT and its related receptors and transporter expression time expressive differences.3. c-Fos protein,5-HT,5-HT2A receptor and 5-HTT involved in the body pain induced by formalin pain feeling process4. Tetrahydropalmatine has a certainly inhibitory effect on pain caused by formaldehyde and inhibition effect of Medium and high dose of tetrahydropalmatine is more significant than ibuprofen.