Relationships Between Autonomic Dysfunction in Type 1 Diabetes Mellitus and Circulating Sex Hormones in Male Rats

Type 1 Diabetes (T1D) is associated with a temporal exaggerated exercise pressor reflex in rats. Previous studies suggest that T1D can alter sex hormones and that supplementation of sex hormones attenuates a normal exercise pressor reflex. PURPOSE: To determine circulating concentrations of sex hormones, specifically estradiol (E), progesterone (P4), and testosterone (T), during different stages of T1D and compare those findings to the exercise pressor reflex evoked by the same male rats. METHODS: Experiments were performed in male Sprague-Dawley T1D (induced via streptozotocin (STZ)) or healthy rats (n= 39). Terminal experiments were conducted at 1-week (early) or 4-6 weeks (late) post STZ or vehicle injection in unanesthetized decerebrate rats. Blood was drawn from the tail vein and serum was aliquoted and stored for analyses. Radioimmunoassays and an ELISA were completed to quantify serum T, E, and P4 concentrations. A two-way ANOVA was used to compare between groups, with significance set at P0.05). No significant differences in concentrations of E were revealed across groups (T1D 1-week: 1.22±1.55; Healthy 1-week: 1.11±0.78; T1D 4-6 weeks: 0.30±0.22; Healthy 4-6 weeks: 0.5±0.46 pg/mL; All P>0.05). Lastly, no significant differences in concentrations of P4 were revealed across groups (T1D 1-week: 0.75±0.47; Healthy 1-week: 0.75±0.42; T1D 4-6 weeks: 1.68±1.09; Healthy 4-6 weeks: 1.00±0.78 ng/mL; All P>0.05). Results revealed no significant correlations amongst these sex hormones and pressor response; all P>0.05.CONCLUSION: Although no shifts in sex hormones occurred, this is the first time these sex hormones have been classified in male T1D and healthy rats across disease progression. Furthermore, these data do not suggest that changes in sex hormone concentration affects the exercise pressor reflex in T1D rats. This project was supported by NIH R01HL 166323.