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目的探讨胃饥饿素(ghrelin)能否通过调控环磷酸腺苷/蛋白激酶A(cAMP/PKA)通路竞争性抑制胰高血糖素样肽1(GLP-1)的促胰岛素分泌效应。方法取8~10周龄雄性SD大鼠5只,分离、纯化大鼠胰岛,经双硫腙(DTZ)和吖啶橙/碘化丙啶(AO/PI)染色鉴定后,每只大鼠挑选60个胰岛,将其随机分成6组并接受不同处理:S_0组(8.3 mmol/L葡萄糖溶液)、S_1组(8.3 mmol/L葡萄糖溶液+10 nmol/L GLP-1)、S_2组(8.3 mmol/L葡萄糖溶液+10nmol/L GLP-1+10 nmol/L ghrelin)、S3组[8.3 mmol/L葡萄糖溶液+10 nmol/L GLP-1+10 nmol/L ghrelin+1μmol/L生长激素促泌素受体1α(GHSR-1α)拮抗剂生长激素释放肽6(D-Lys3-GHRP-6)]、S4组(8.3 mmol/L葡萄糖溶液+10nmol/L GLP-1+10 nmol/L ghrelin+5μmol/L腺苷酸环化酶激动剂毛喉素)、S_5组(8.3 mmol/L葡萄糖溶液+10 nmol/L GLP-1+10 nmol/L ghrelin+10μmol/L PKA激动剂6-Phe-cAMP);所有试剂均于前一试剂处理10 min后依次加入后一试剂共同处理,每组胰岛的所有处理时间共3 h。采用ELISA法检测各组胰岛培养液中胰岛素和cAMP的浓度。结果S1组胰岛细胞分泌胰岛素和释放c AMP的浓度均高于S0组(P均<0.05),S_2组均低于S_1组(P均<0.05)。S_3、S_4和S_5组胰岛细胞分泌胰岛素和释放cAMP的浓度均高于S2组(P均<0.05)。结论 Ghrelin能够抑制GLP-1的促胰岛素分泌效应,其作用机制可能是通过cAMP/PKA通路竞争性抑制GLP-1的促分泌效应。
Objective To investigate whether ghrelin can competitively inhibit the insulinotropic effect of glucagon-like peptide 1 (GLP-1) through regulating the cAMP / PKA pathway. Methods Five male Sprague Dawley rats aged 8-10 weeks were used to isolate and purify rat islets. After identification by dithizone (DTZ) and acridine orange / propidium iodide (AO / PI) staining, each rat Sixty islets were selected and randomly divided into 6 groups and received different treatments: S_0 group (8.3 mmol / L glucose solution), S_1 group (8.3 mmol / L glucose solution + 10 nmol / L GLP-1) 10 mmol / L glucose solution + 10 nmol / L GLP-1 + 10 nmol / L ghrelin), S3 group [8.3 mmol / L glucose solution +10 nmol / L GLP-1 +10 nmol / L ghrelin + GHSR-1α antagonist ghrelin 6 (D-Lys3-GHRP-6), S4 group (8.3 mmol / L glucose solution +10 nmol / L GLP-1 +10 nmol / g ghrelin +5 μmol / L adenylate cyclase agonist forskolin), S_5 group (8.3 mmol / L glucose solution + 10 nmol / L GLP-1 + 10 nmol / L ghrelin + 10 μmol / L PKA agonist 6-Phe -cAMP). All reagents were treated with the former reagent 10 min followed by the latter reagent co-treatment. The total processing time of each islet was 3 h. The concentration of insulin and cAMP in islet culture medium of each group was detected by ELISA. Results The insulin secretion and cAMP release of islet cells in S1 group were higher than those in S0 group (all P <0.05), while those in S 2 group were lower than those in S 1 group (P <0.05). The concentrations of insulin and cAMP released from islets in S_3, S_4 and S_5 groups were higher than those in S2 group (all P <0.05). Conclusions Ghrelin can inhibit the insulinotropic effect of GLP-1, which may be due to the competitive inhibition of the secretive effect of GLP-1 through the cAMP / PKA pathway.