摘要目的 研究下丘脑室旁核(hypothalamic paraventricular nucleus,PVN)内注射谷氨酸( glutamate,Glu)对慢性内脏高敏感性(chronic visceral hypersensitivity,CVH)大鼠慢性内脏痛的影响及其可能的机制.方法 新生SD大鼠,在出生后第8、10、12天分别给予结直肠扩张法制备CVH大鼠模型.取30只制备成功的CVH模型大鼠,随机分为CVH模型组( CVH组)、CVH+PVN内注射生理盐水组(NS组)、CVH+PVN内注射Glu组3、6、12 μg 组( G3组、G6组、G12组),每组6只,另取体质量相匹配的6只SD大鼠作为假手术组( Sham组).采用痛阈、腹壁撤退反射( abdominal withdrawal reflex,AWR)评分和腹外斜肌肌电图(abdominal external oblique muscle electromyography,EMG)评价大鼠的痛行为.免疫组化染色法检测大鼠脑内精氨酸加压素(arginine vasopressin,AVP)表达水平和结肠组织细胞增殖情况,Tunel法检测结肠组织细胞凋亡情况.结果 与NS组比较,G3、G6、G12组大鼠的痛阈均升高,AWR评分和EMG幅度均降低,差异有统计学意义[痛阈:t=7. 65,16. 31,24. 78,均P<0. 05;AWR评分:t=-2. 98,-4. 77,-7. 29,均P<0. 05;EMG幅度:t=-3. 06,-5. 75,-8. 92,均P<0. 05].与Sham组[(42. 63±5. 20)%]比较,CVH组和NS组大鼠PVN内AVP 表达下降[( 18. 67± 2. 94)%,(17. 53±2. 47)%;t=6. 95,7. 56,均 P<0. 05],大鼠PVN内注射不同剂量Glu后,AVP表达升高,其中G12组为[(37. 03± 7. 63)%],与NS组比较,差异有统计学意义( t=-4. 21,P<0. 05).与Sham组[(65. 48±1. 68)%]比较,CVH组和NS组大鼠结肠组织黏膜细胞增殖细胞核抗原(prolifera-ting cell nuclear antigen,PCNA)表达降低[(18. 39±1. 67)%,(17. 69±1. 68)%;t=34. 35,34. 80,均 P<0. 05],PVN内注射不同剂量Glu后,PCNA表达升高,其中G12组为[(59. 91±5. 63)%],与NS组比较,差异有统计学意义(t=-12. 44,P<0. 05).与Sham组[(23. 38±11. 40)%]比较,CVH组和NS组大鼠结肠组织黏膜凋亡细胞表达升高[( 83. 79± 3. 57)%,(80. 91± 2. 47)%;t=-8. 77,-8. 54,均 P<0. 05],PVN内注射不同剂量Glu后,凋亡细胞表达降低,其中G12组为[(18. 15±6. 49)%],与NS组比较,差异有统计学意义(t=15. 65,P<0. 05).结论 下丘脑PVN内注射Glu能缓解CVH大鼠的内脏痛行为,其机制可能与精氨酸加压素有关.

abstractsObjective To investigate the effects of glutamate (Glu) injected into hypothalamic pa-raventricular nucleus (PVN) on visceral pain of chronic visceral hypersensitivity (CVH) rats and its possi-ble mechanism. Methods Newborn SD rats were given CVH rat model by colorectal distension (CRD) on the 8th,10th and 12th day after birth. Thirty rats with successful CVH model were randomly divided into CVH model group (CVH group),CVH + injection of saline into PVN group (NS group),CVH+ injection of Glu into PVN (3,6,and 12 μg Glu,namely G3,G6,and G12,respectively),6 rats in each group,and 6 SD rats with matching body mass were taken as sham operation group (Sham group). The pain behavior of the rats was evaluated by pain threshold,abdominal withdrawal reflex (AWR) score,and abdominal external ob-lique muscle electromyography (EMG). The expression of arginine vasopressin (AVP) and the proliferation of colon tissue were detected by immunohistochemical staining. The apoptosis of colon tissue was detected by TUNEL. Results Compared with the NS group, the pain thresholds of the G3, G6 and G12 groups in-creased,and the AWR scores and EMG amplitudes decreased. The differences were statistically significant (Pain threshold:t=7. 65,16. 31,24. 78,both P<0. 05;AWR scores:t=-2. 98,-4. 77,-7. 29,both P<0. 05;EMG amplitudes:t=-3. 06,-5. 75,-8. 92,both P<0. 05). Compared with the Sham group,the expression of AVP in PVN of the CVH group and NS group decreased ((42. 63±5. 20) %,(18. 67±2. 94) %,(17. 53± 2. 47) %; t=6. 95,t=7. 56,both P<0. 05). The expression of AVP was increased after different doses of Glu into PVN,and the AVP level in G12 group ((18. 15±6. 49)%) was higher than that of NS group,the difference was statistically significant (t=-4. 21,P<0. 05). Compared with the Sham group,the expression of PCNA in colonic mucosal cells of the CVH group and NS group decreased ((65. 48±1. 68) %,(18. 39± 1. 67) %,(17. 69±1. 68) %;t=34. 35,t=34. 80,both P<0. 05). The expression of PCNA was increased after different doses of Glu injected into PVN,and the PCNA level in G12 group ((59. 91±5. 63)%) was higher than that of NS group,the difference was statistically significant (t=-12. 44,P<0. 05). Compared with the Sham group,the expression of apoptotic cells in colonic mucosal cells of the CVH group and NS group increased ((23. 38±11. 40)%,(83. 79± 3. 57)%,(80. 91± 2. 47)%;t=-8. 77,t=-8. 54,both P<0. 05). The expression of apoptotic cells was decreased after different doses of Glu into PVN,and the G12 group was ((18. 15±6. 49) %). Compared with NS group,the difference was statistically significant ( t=15. 65,P<0. 05). Conclusion Injection of Glu into hypothalamic PVN can alleviate the visceral pain be-haviors in CVH rats,and its mechanism may be related to arginine vasopressin.