下丘脑中Ghrelin、Obestatin水平及其受体表达与糖尿病大鼠胃排空的关系

Association of gastric emptying with ghrelin, obestatin and receptor （GHSR, GPR-39 ） in hypothalarnus of diabetic rats

目的探讨糖尿病大鼠下丘脑胃促生长素（Ghrelin）、肥胖抑素（Obestatin）水平及受体表达与胃排空的关系。方法60只雄性Wistar大鼠随机等分为正常对照组、糖尿病组、胰岛素组。链脲佐菌素（STZ）造模，给药2周、6周后测胃排空及下丘脑Ghrelin、Obestatin、生长激素促分泌激素受体（GHSR）和孤儿蛋白受体39（GPR-39）。结果2周后，糖尿病和胰岛素组的胃排空率（％）（74±8、40±5）、Ghrelin（ng／g）（52±9、51±7）和Ghrelin／Obestatin（3．8±1．0、2．8±1．0）分别较正常组[32％±7％、（39±11）ng／g、2．1±0．8]高（均P〈0．05）。糖尿病组Obestatin（ng／g）（14．2±2．0）较正常组（21．7±4．7）低（P〈0．05），而GHSR（1．26±0．46）较正常组（0．77±0．21）高（P〈0．05）。胃排空率与Ghrelin、Ghrelin／Obestatin和GHSR／β-肌动蛋白（β-actin）正相关（r=0．49；r=0．63；r=0．73；P〈0．01），与Obestatin负相关（r=-0．74，P〈0．01）。6周后，糖尿病和胰岛素组胃排空率（78．97％±8．13％、44．06％±5．06％）均较正常组（35．06％±3．91％）高（均P〈0．01）。胃排空率与Ghrelin／Obestatin呈正相关（r=0．40，P〈0．05），未检测到GPR-39。结论高血糖早期胃排空加速可能受Ghrelin和GHSR表达增加影响，而持续期受Ghrelin／Obestatin增大影响。

Objective To investigate the association of gastric emptying with ghrelin, obestatin and GHSR, GPR-39 in hypothalamus of diabetic rats. Methods Sixty Wistar rats were randomly divided into three groups ： a normal control group （ NC, n = 20）, a diabetes mellitus group （ DM, n = 20） induced by intraperitoneal injection of streptozotocin （STZ） and an insulin treated group （INS, n = 20）. After two and six weeks of STZ injection, gastric emptying was measured by intragastric administration of phenol red, ghrelin and obestatin in hypothalamus measured by ELISA （ enzyme-linked immunosorbent assay） and GHSR and GPR-39 by RT-PCR （reverse transcription-polymerase chain reaction） . Results After two weeks of STZ injection, gastric emptying （%） （74 ±8, 40 ±5）, ghrelin level（ng/g） （52± 9, 51 ±7）and ratio of ghrelin/obestatin（3.8 ± 1.0, 2. 8± 1.0）increased significantly in DM and INS groups compared to those in N C group [ 32% ± 7 %, （39 ± 11 ） ng/g, 2. 1 ±0. 8, all P 〈 0. 05 ]. Obestatin level（ng/g） （ 14. 2± 2.0）of hypothesis decreased significantly in DM group as compared to those in NC group（21.7 ± 4. 7 ）while GHSR/ [3-aetin increased significantly （ 1.26 ± 0. 46 vs 0. 77 ± 0. 21, P 〈 0. 05 ）. Gastric emptying was positively correlated with ghrelin, ghrelin/obestatin and GHSR/β-actin of hypothalamus （ r = 0. 49 ; r = 0. 63 ; r = 0. 73; P〈0. 01）. But there was a negative correlation with obestatin of hypothalamus （r = -0. 74, P 〈 0. 01 ）. After six weeks of STZ injection, gastric emptying （78.97% ± 8. 13% vs 44. 06% ± 5.06% ） increased significantly in DM and INS groups as compared to those in NC group（35.06%± 3. 91%, P 〈 0. 01 ）. Gastric emptying was positively correlated with ghrelin/obestatin of hypothalamus （ r = 0.40, P 〈 0. 05）. There was no detection of GPR-39 in hypothalamus. Conclusion The rapid gastric emptying may be due to the rising levels of ghrelin and GHSR in hypothalamus during early hyperglycemia. And the duration of hyperglycemia is affected by the rising ratio of ghrelin/obestatin.