Effects Of PTH And Insulin Secretion In Mice And Mechanism

Objective:To observe the changes of insulin secretion(GSIS)induced by parathyroid hormone(PTH1-34)in primary C57 mice.To explore the mechanism of parathyroid hormone on islets.Methods:The cells were divided into solvent control group(Con group)and parathyroid hormone group(PTH group)by digesting C57 mice pancreas with collagenase V,and the pancreatic islets of C57 mice were observed after the intervention of parathyroid hormone in low glucose(2.8G)and high glucose(16.7G).And the relationship with calcium was observed by Calcium imaging technology.The relationship between insulin secretion and cAMP was studied by detecting cAMP content in islet cells after PTH intervention.Results:(1)The islets were round,oval-shaped solid particles with clear boundaries and no burrs.(2)The insulin secretion was measured by PTH1-34 in vitro.The insulin secretion of Con group and PTH group(Ca=1mM)were respectively(5.28±0.57)uIU/ml?(1.81±0.16)uIU/ml?(2.28±0.27)uIU/ml?(2.83±0.54)uIU/ml in 2.8mM glucose,The total amount of insulin in PTH group was lower than Con group in low glucose group(P <0.05),and the difference was statistically significant.In 16.7mM glucose group,The insulin secretion in Con and PTH group was respectively(49.66±5.97)uIU / ml,?(37.45±1.84)uIU / ml?(30.96±2.88)uIU / ml?(30.70±2.33)uIU / ml,and the total insulin in PTH group was significantly lower than Con group(P <0.05),and the difference was statistically significant;16.7G Con group of insulin was significantly higher than 2.8G Con group,P<0.001,which indirectly proved the function of islets were good.The insulin content(Ca=2.5 mM)was measured in the Con group and the PTH group in the 2.8 m M glucose were respectively(2.72 ± 0.75)uIU / ml?(2.31 ± 0.56)uIU / ml,?(2.91 ± 0.74)uIU / ml?(3.74 ± 0.43)uIU / ml;The insulin content in the Con group and the PTH group respectively were(30.98 ± 3.63)uIU / ml?(35.69 ± 4.29)uIU / ml?(31.38 ± 6.18)uIU /ml,?(32.90 ± 2.07)uIU / ml in 16.7 mM glucose.showing that PTH had no significant effect on insulin secretion.The total amount of insulin in Con group was significantly higher than that in 2.8 m M glucose group(P <0.001).(3)By calcium imaging technique,the Ration of Fura 2(340/380)in 16.7 mM group,16.7 mM + PTH group were respectively(0.52 ± 0.01)?(0.80 ± 0.03)?(1.19 ± 340),Ration of Fura 2(340/380)of 16.7mM + PTH group was significantly higher than 16.7mM group,P <0.05,and the difference was statistically significant.(4)The content of cAMP in the 16.7mM group,16.7mM + PTH group and 16.7mM+ Forskolin group were respectively(0.19±0.02)nmol / L?(0.22±0.03)nmol / L?(0.45±0.11)nmol / L.There was no significant difference between 16.7m M + PTH group and16.7mM group;CAMP content of 16.7mM + Forskolin group was significantly higher than 16.7mM group,P <0.05,and the difference was statistically significant,which indirectly proved the function of islets were good.Conclusion:(1)The use of collagenase V to digest the pancreas and the manual selection of the obtained islets with high purity,activity and function.(2)Compared with lower glucose,insulin secretion was significantly increased under high glucose condition.(3)under low glucose and high glucose conditions,ultra-physiological dose of PTH on insulin secretion has an inhibitory effect.(4)The inhibitory effect was independent of cAMP content in islet cells.(5)In view of the experimental results,presumably PTH can promote intracellular calcium flow into the islet cells,resulting in calcium overload and the formation of calcium toxicity.Further inhibit the secretion of insulin.