Previous studies using male rodents showed the adipocyte-derived hormone leptin acts in the brain to regulate cardiovascular function, energy balance and glucose homeostasis. The importance of sex differences in cardiometabolic responses to leptin, however, is still unclear. We examined potential sex differences in leptin's chronic central nervous system (CNS)-mediated actions on blood pressure (BP), heart rate (HR), appetite, and glucose homeostasis in normal and type 1 diabetic rats. Female (n=6) and male (n=5) Sprague-Dawley rats were instrumented with intracerebroventricular (ICV) cannulas for continuous 7-day leptin infusion (15 mg/day) and BP and HR were measured by telemetry 24-hrs/day. At baseline, females had lower MAP (96±3 vs. 104±4 mmHg, p<0.05) but higher HR (375±5 vs. 335±5 bpm, p<0.05) compared to males. Following leptin treatment, we observed similar changes in BP (~3 mmHg) and HR (~25 bpm) in both sexes. Females had significantly reduced body weight (BW, 283±2 vs. 417±7 g, p<0.05) and lower caloric intake (162±20 vs. 192±9 kcal/kg of BW, p<0.05) compared to males, and leptin infusion reduced BW (-10%) and caloric intake (-62%) similarly in both sexes. Leptin infusion also caused similar reductions in fasting insulin and blood glucose levels in both sexes. In female and male rats with streptozotocin-induced diabetes (n=5/sex), ICV leptin treatment for 7 days completely normalized glucose levels. These results show that leptin's CNS effects on BP, HR, glucose regulation and energy homeostasis are similar in male and female rats. Therefore, our results provide no evidence for sex differences in leptin's brain-mediated cardiovascular or metabolic actions.

中文翻译：

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慢性中枢神经系统介导的瘦素心脏代谢作用：性别差异的潜在作用

先前使用雄性啮齿动物的研究表明，脂肪细胞衍生的激素瘦素在大脑中起作用，以调节心血管功能、能量平衡和葡萄糖稳态。然而，性别差异对瘦素的心脏代谢反应的重要性仍不清楚。我们检查了瘦素慢性中枢神经系统 (CNS) 介导的对正常和 1 型糖尿病大鼠的血压 (BP)、心率 (HR)、食欲和葡萄糖稳态的潜在性别差异。雌性 (n=6) 和雄性 (n=5) Sprague-Dawley 大鼠使用脑室内 (ICV) 插管进行连续 7 天瘦素输注（15 mg/天），并通过遥测 24 小时/小时测量 BP 和 HR日。在基线时，与男性相比，女性的 MAP 较低（96±3 对 104±4 mmHg，p<0.05），但 HR 较高（375±5 对 335±5 bpm，p<0.05）。瘦素治疗后，我们观察到两性的 BP（~3 mmHg）和 HR（~25 bpm）的相似变化。与男性相比，女性体重显着降低（BW，283±2 对 417±7 g，p<0.05）和热量摄入（162±20 对 192±9 kcal/kg BW，p<0.05），和瘦素输注同样减少了两性的体重（-10%）和热量摄入（-62%）。瘦素输注也导致男女空腹胰岛素和血糖水平的类似降低。在患有链脲佐菌素诱导的糖尿病（n=5/性别）的雌性和雄性大鼠中，ICV 瘦素治疗 7 天后血糖水平完全正常化。这些结果表明瘦素对 BP、HR、葡萄糖调节和能量稳态的 CNS 作用在雄性和雌性大鼠中是相似的。因此，我们的结果没有为瘦素的性别差异提供证据。