Exercise Improves Insulin and Leptin Sensitivity in Hypothalamus of Wistar Rats
Article Figures & Tables
Figures
- FIG. 1.
Physiological characteristics of control and exercised rats. Effects of exercise on plasma glucose concentration (mmol/l) (A), plasma insulin concentration (pmol/l) (B), and plasma leptin concentration (ng/ml) (C). Data are the means ± SE, n = 6 animals per group. *P < 0.01 vs. control. □, control: insulin i.c.v.; ○, control: leptin i.c.v.; ▪, exercise: insulin i.c.v.; •, exercise: leptin i.c.v.
- FIG. 2.
Leptin inhibition of the 12-h cumulative food intake and leptin signaling in the hypothalamus of control and exercised rats. Vehicle (−) or leptin (+) was injected intracerebroventricularly after a 6-h session of exercise, and rats were immediately exposed to food for 12 h. Data are the means ± SE of 8–14 animals per group (A). At 15 min after the infusion, tissue extracts were immunoprecipitated (IP) with anti-ObR and anti-JAK2 and immunoblotted (IB) with anti-phosphotyrosine antibody (pY) (B and C, upper panels). Whole-tissue extracts were immunoblotted with pSTAT3 antibody (D, upper panel). Stripped membranes were reblotted with anti-ObR, anti-JAK2, and anti-STAT3 antibodies (B–D, lower panels). The results of scanning densitometry were expressed as arbitrary units. Columns and bars represent the means ± SE, n = 8 animals per group. *P < 0.05, leptin control vs. leptin exercise; #P < 0.05, leptin control vs. control. □, control; ▪, exercise.
- FIG. 3.
Leptin signaling in the hypothalamus of control and exercised rats. Hypothalamus extracts from rats injected with vehicle (−) or leptin (+) were prepared as described in research design and methods. At 5 min after the infusion tissue, extracts were immunoprecipitated (IP) with anti–IRS-1 and anti–IRS-2 antibodies and immunoblotted (IB) with anti-phosphotyrosine (pY) (A and C, upper panels), anti–PI 3-kinase (A and C, middle panels), anti–IRS-1, and anti–IRS-2 antibodies (A and C, lower panels). PI 3-kinase assays were performed as described. Fluorographs show the silica thin-layer chromatography plates of IRS-1–or IRS-2–associated PI 3-kinase activity (B and D). The results of scanning densitometry were expressed as arbitrary units. Columns and bars represent the means ± SE, n = 6 animals per group. *P < 0.05, leptin control vs. leptin exercise. □, control; ▪, exercise. PIP, the migration position of PI 3–phosphate.
- FIG. 4.
Insulin inhibition of 12-h cumulative food intake and insulin signaling in the hypothalami of control and exercised rats. Vehicle or insulin was injected intracerebroventricularly after a session of 6-h exercise, and rats were immediately exposed to food for 12 h. Data are the means ± SE of 8–14 animals per group (A). At 15 min after the infusion, tissue extracts were immunoprecipitated (IP) with anti–insulin receptor antibody and immunoblotted (IB) with anti-phosphotyrosine antibody (pY) (B, upper panel) and anti–insulin receptor antibody (B, lower panel). Tissue extracts were also immunoprecipitated with anti–IRS-1 and anti–IRS-2 antibodies and immunoblotted with anti-phosphotyrosine (C and D, upper panels), anti–PI 3-kinase (C and D, middle panels), or anti–IRS-1 or anti–IRS-2 antibodies (C and D, lower panels). The results of scanning densitometry were expressed as arbitrary units. Columns and bars represent the means ± SE, n = 6 animals per group. *P < 0.05, insulin control vs. insulin exercise; #P < 0.05, insulin control vs. control. □, control; ▪, exercise.
- FIG. 5.
Insulin signaling in the hypothalami of control and exercised rats. Hypothalami from rats injected with vehicle (−) or insulin (+) were prepared 15 min after the infusion, as described in research design and methods. Fluorographs show the silica thin-layer chromatography plates of IRS-1–or IRS-2–associated PI 3-kinase activity. At 15 min after the infusion, whole-tissue extracts were immunoblotted (IB) with anti–pAkt serine 473 (C, upper panel) or anti–pAkt threonine 308 (D, upper panel) and with anti-Akt antibodies (C and D, lower panels). The results of scanning densitometry were expressed as arbitrary units. Columns and bars represent the means ± SE, n = 6 animals per group. *P < 0.05, insulin control vs. insulin exercise. □, control; ▪, exercise. PIP, the migration position of PI 3–phosphate (A and B).
- FIG. 6.
Blockade of leptin and insulin-induced inhibition of food intake by anti–IL-6. Hypothalami from rats were prepared as described in research design and methods. Tissue extracts from control and exercised rats were immunoblotted with anti–IL-6 antibody (A). Leptin and insulin were injected intracerebroventricularly in control rats, exercised rats, and exercised rats pretreated with anti–IL-6 at the doses indicated, and the animals were immediately exposed to food for 12 h. Data are the means ± SE of 8–14 animals per group (B and C). Tissue extracts from control rats, exercised rats, and exercised rats pretreated with anti–IL-6 were treated with leptin and immunoprecipitated (IP) with anti-JAK2 antibody and immunoblotted (IB) with anti-phosphotyrosine antibody (D, upper panel) and with anti-JAK2 (D, lower panel). Whole-tissue extracts were immunoblotted with anti–phospho STAT3 antibody (E, lower panel) and with anti-STAT3 (E, lower panel). Hypothalamus tissue extracts from control, exercised, and exercised rats pretreated with anti–IL-6 were treated with insulin and immunoprecipitated with anti–insulin receptor antibody and immunoblotted with anti-phosphotyrosine antibody (F, upper panel) and with anti–insulin receptor (F, lower panel). Whole-tissue extracts were immunoblotted with anti–phosphoserine 473 and anti–threonine 308 Akt antibody (G and H, lower panels) and with anti-Akt (G and H, lower panels). The results of scanning densitometry are expressed as arbitrary units. Columns and bars represent the means ± SE, n = 8 animals per group. #P < 0.05, exercise vs. control; *P < 0.05, exercise + anti–IL-6 vs. exercise. □, control; ▪, exercise;
, exercise + anti–IL-6.
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