| Objective:To study the impact of hypoglycemia stress on the hypothalamus-pituitary-thyroid axis by examining the serum level of TH hormones and the expression of TSH? mRNA and TSH? protein in the pituitary.Methods:Thirty-seven male Sprague Dawley rats(280-320 g body weight)were randomly divided into a 0-minute group(control group),a 15-minute group,a 30-minute group,a 60-minute group,and a 90-minute group.All experimental rats underwent cervical and venous catheterization under anesthesia,and glucose clamps were performed within 16-24 hours after catheterization.In the control group,the specimens were collected directly without a clamp test.The experimental group was established a hypoglycemic rat model(adjusted blood glucose fluctuations of 2.2-2.8 mmol/L)by the clamp test,which lasted for 15 minutes,30 minutes,60 minutes and 90 minutes?the rats were weighted and then anaesthetizedto collect blood from heart.After the blood was taken off,the pituitary was quickly separated and removed.Serum FT3,FT4,TT4,and TSH levels were measured by ELISA.The expression of TSH? mRNA in pituitary tissues of rats in each group was analyzed by real-time fluorescent quantitative PCR.The expression of TSH? protein in pituitary tissues was analyzed by Western Blot.SPSS22.0software was used to process and analyze the data.The experimental data were expressed as (?)ąSD.One-way analysis of variance was used.P<0.05 was considered statistically significant.Results:1.The level of serum FT3 increased 15 minutes after hypoglycemia stress compared with that of 0 minute group(p<0.05).The level of FT3 in 30 minute group was significantly higher than that of 0 minute group(p<0.05),slightly lower than those in the15-minute group(no significant difference),and lighter than the 0-minute group Degree increased(no statistical difference).2.After 15 minutes of hypoglycemia stress,serum FT4 increased significantly compared with 0 minute group(p<0.05);30 minutes serum FT4 slightly lower than 15 minutes group(no significant difference),compared with 0minutes mild(No significant difference);serum FT4 in 60 min group was slightly lower than that in 15 min group and 30 min group(no significant difference),slightly higherthan 0min group(no significant difference);90min group Serum FT4 was significantly lower than those of 15 minutes,30 minutes and 60 minutes(p<0.05),but slightly lower than that of 0(no significant difference).3.After 15 minutes,hypoglycemia stress elevated serum TT4,0 minutes group was significantly different(p<0.05)compared;serum TT4 than 30 minutes 0 minutes significantly increased significantly(p<0.05),compared with 15 minutes group mild(P<0.05),and the level of TT4 in 60-minute group was significantly higher than that in 0-minute group(p<0.05),slightly higher than that in15-minute group and 30-minute group(no statistical difference)Serum FT4 was significantly lower than that of 15 minutes,30 minutes and 60 minutes(p<0.05),but slightly lower than that of 0(no statistical difference).4.After 15 minutes,hypoglycemia stress slightly decreased serum TSH(no significant difference);30 minutes of serum TSH group than 0 minutes,15 minutes increased slightly group(no statistical difference);serum TSH than 60 minutes 0(P<0.05),slightly increased compared with 30 minutes(no significant difference);Serum TSH decreased in 90 minutes group compared with 0minute group,15 minute group,30 minute group,The 60-minute group was slightly decreased(no statistical difference).5.Hypoglycemia stress pituitary TSH?mRNA expression levels increased 15 minutes later,compared with the 0-minute group was significantly different(p<0.05);the other groups were not statistically significant.(P<0.05).6.TSH?protein expression in pituitary increased after hypoglycemia stress for 15minutes(p<0.05);TSH?protein expression increased significantly(P<0.05)in 30 minutes than that in 0 minutes,but slightly increased compared with that in 15 minutes(no statistical difference);TSH?protein expression in pituitary at 60 minutes was significantly lower than that at 30 minutes(p<0.05),but no significant difference compared with 0 minutes and 15 minutes.TSH?protein expression in pituitary at 90 minutes was significantly lower than that at 30 minutes(p<0.05),No significant difference compared with 0 minute group,15 minute group,60 minute group.Conclusion:1.Hypoglycemia stress can affect the HPA axis in rats.2.Hypoglycemic stress can cause serum FT3,FT4,TT4,and TSH levels to rise first and then decrease.3.Hypoglycemic stress can induce the expression level of TSH? mRNA in the pituitary increase first and then decrease.4.Hypoglycemic stress can cause the expression level of TSH?protein in the pituitary of rats to increase first and then decrease. |
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