L型钙通道介导垂体腺苷酸环化酶激活肽38对大鼠胰岛素分泌的促进作用及其机制研究

目的研究垂体腺苷酸环化酶激活肽38(PACAP38)对大鼠胰岛素分泌的影响及其机制。方法 (1)将大鼠胰岛和胰岛细胞分为4组:正常组(2.8 mmol·L^-1葡萄糖)、模型组(8.3 mmol·L^-1葡萄糖)和低,高2个剂量实验组(模型组+1,10 nmol·L^-1 PACAP38),测定不同干预下的胰岛素分泌量。(2)将大鼠胰岛和胰岛细胞分为5组:正常组、模型组、高剂量实验组、阿折地平(L型钙通道阻滞药)组(模型组+0.1μmol·L^-1阿折地平)和联合组(阿折地平组+高剂量实验组),用胰岛素分泌实验和钙成像技术分别检测阿折地平干预下胰岛素分泌量和β细胞内Ca^2+浓度(F-F0值)水平。结果 (1)正常组、模型组和低、高2个剂量实验组的胰岛素分泌量分别为(86.74±4.05),(165.63±5.26),(175.03±5.21)和(209.28±4.13)μu·mL^-1,模型组与正常组相比,胰岛素分泌量明显增加,差异有统计学意义(P<0.01);高剂量实验组与模型组相比,胰岛素分泌显著增加,差异有统计学意义(P<0.05)。(2)正常组、模型组、高剂量实验组、阿折地平组和联合组的胰岛素分泌量分别为(46.93±4.58),(79.11±8.02),(135.65±3.68),(72.78±7.95),(78.51±5.13)μu·mL^-1;这5组的Ca^2+浓度分别为3.00×10^-2±0.12,6.57×10^-2±0.35,1.40×10^-1±0.46,7.71×10^-2±0.42,8.00×10^-2±0.43,上述指标:模型组与正常组比较,差异均有统计学意义(均P<0.01);高剂量实验组与模型组比较,差异均有统计学意义(均P<0.001);联合组与高剂量实验组比较,差异均有统计学意义(均P<0.001);阿折地平与模型组比较,差异均无统计学意义(均P>0.05)。结论 PACAP38通过作用于L型钙通道,使β细胞内Ca^2+浓度升高,最终促进胰岛素分泌。

L-type calcium channel mediates the promoting effect of pituitary adenylate cyclase-activating polypeptide-38 on insulin secretion in rats and mechanism

Objective To explore the effect of pituitary adenylate cyclase-activating polypeptide-38(PACAP38)on insulin secretion in rats and the mechanism. Methods(1) Rat islets and islet cells were divided into 4 groups: 2.8 mmol·L^-1 glucose as normal group, 8.3 mmol·L^-1 glucose as model group, 8.3 mmol·L^-1 glucose+1,10 nmol·L^-1 PACAP38 as experimental-L, experimental-H groups. The insulin secretion was determined under different interventions.(2) Rat islets and cells was segmented into five groups: normal group,model group,experimental-H group, azelnidipine group(8.3 mmol·L^-1 glucose+0.1 μmol·L^-1 azelnidipine), combination group(8.3 mmol·L^-1 glucose + 0. 1 μmol·L^-1 azelnidipine + 10 nmol·L^-1 PACAP38). Insulin secretion and Ca^2+ concentration(F-F0 value) in β cells under the intervention of of L-type calcium channel blocker were detected by insulin secretion test and calcium imaging technology,respectively. Results(1) The level of insulin secretion in normal group,model group,experimental-L group and experimental-H group were(86. 74 ± 4. 05),(165. 63 ± 5. 26),(175. 03 ± 5. 21),(209. 28 ± 4. 13) μu·mL^-1;comparison between model group and normal group,the difference was significantly(P < 0. 01);comparison between experimental-H group and model group,the difference was significantly(P < 0. 05).(2) The level of insulin secretion in normal group,model group,experimental-H group,azelnidipine group and combination group were(46. 93 ± 4. 58),(79. 11 ± 8. 02),(135. 65 ± 3. 68),(72. 78 ± 7. 95),(78. 51 ± 5. 13) μu·mL^-1;the Ca^2+ concentrations of these 5 groups were 3. 00 × 10^-2± 0. 12,6. 57 × 10^-2± 0. 35,1. 40 × 10^-1± 0. 46,7. 71 × 10^-2± 0. 42,8. 00 × 10^-2± 0. 43;comparison between model group and normal group,the difference of the factors were significantly(all P < 0. 01);comparison between experimental-H group and model group,the difference of the factors were significantly(all P < 0. 001);comparison between combination group and experimental-H group,the difference of the factors were significantly(all P < 0. 001);comparison between azelnidipine group and model group,the difference of the factors were not significantly(all P > 0. 05). Conclusion PACAP38 stimulates insulin secretion via acting on L-type Ca^2+ channels and incresing intracellular Ca^2+ concentrations.