Exercise Training Attenuates Hypertension Through TLR4/MyD88/NF-κB Signaling in the Hypothalamic Paraventricular Nucleus

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  FIGURE 1. (A) Experimental Design. Adult male SD rats were preselected to be able to run in a small-animal treadmill before the start of the experiment. After 1 week of selecting, the rats were allocated to kept Sed or ExT. All rats were implanted with the bilateral PVN cannulae, and then were allowed to recover for a week. 2K1C or SHAM surgeries were carried out at week zero. Then the ExT groups were put on a treadmill and let run at an initial speed of 5.0 m/min, and the speed was gradually increased to 16 m/min in the second week and kept through the end of exercise. (B) ExT or PVN infusion of TAK242 lowered blood pressure of 2K1C hypertensive rats. ExT reduced SBP in 2K1C + ExT + vehicle in comparison with 2K1C + Sed + vehicle rats from week six till the end of the study. PVN infusion of TAK242 in the 2K1C + Sed + TAK242 rats also reduced SBP in comparing with 2K1C + Sed + vehicle group. ∗P < 0.05 versus SHAM rats (SHAM + Sed + PVN vehicle, SHAM + ExT + PVN vehicle or SHAM + Sed + PVN TAK242). †P < 0.05 (2K1C + ExT + PVN vehicle or 2K1C + Sed + PVN TAK242) versus 2K1C + Sed + PVN vehicle. ΔP < 0.05 2K1C + Sed + PVN TAK242 versus 2K1C + ExT + PVN vehicle.

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  FIGURE 2. Effect of ExT or PVN infusion of TAK242 on renal sympathetic nerve activity (RSNA) in 2K1C hypertensive rats and SHAM rats. (A) Original tracings of RSNA. (B) Statistic of RSNA. 2K1C hypertensive rats had higher RSNA than in SHAM rats. ExT or PVN infusion of TAK242 attenuated RSNA of 2K1C rats. ∗P < 0.05 versus SHAM rats (SHAM + Sed + PVN vehicle, SHAM + ExT + PVN vehicle or SHAM + Sed + PVN TAK242). †P < 0.05 (2K1C + ExT + PVN vehicle or 2K1C + Sed + PVN TAK242) versus 2K1C + Sed + PVN vehicle.

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  FIGURE 3. Effect of ExT or PVN infusion of TAK242 on the plasma levels of NE and EPI, and PVN level of NF-κB activation in 2K1C hypertensive rats and SHAM rats. Levels of plasma NE (A) and EPI (B), and PVN level of NF-κB p65 (C) activity was shown in 2K1C hypertensive rats, sham rats and both groups after ExT or PVN infusion of TAK242. ∗P < 0.05 versus SHAM rats (SHAM + Sed + PVN vehicle, SHAM + ExT + PVN vehicle or SHAM + Sed + PVN TAK242). †P < 0.05 (2K1C + ExT + PVN vehicle or 2K1C + Sed + PVN TAK242) versus 2K1C + Sed + PVN vehicle.

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  FIGURE 4. ExT or PVN infusion of TAK242 reduced PVN level of Fra-LI of 2K1C hypertensive rats. (A) Immunohistochemistry staining of Fra-LI in the PVN. (B) Statistic of Fra-LI expression in the PVN. ∗P < 0.05 versus SHAM rats (SHAM + Sed + PVN vehicle, SHAM + ExT + PVN vehicle or SHAM + Sed + PVN TAK242). †P < 0.05 (2K1C + ExT + PVN vehicle or 2K1C + Sed + PVN TAK242) versus 2K1C + Sed + PVN vehicle.

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  FIGURE 5. ExT or PVN infusion of TAK242 attenuated PVN levels of TLR4 and MyD88 mRNA and protein expression of 2K1C hypertensive rats. (A) Immunoreactive bands of TLR4, MyD88 and β-actin in the PVN. (B) Statistic of TLR4 and MyD88 protein expression. (C,D) Statistic of TLR4 and MyD88 mRNA levels. ∗P < 0.05 versus SHAM rats (SHAM + Sed + PVN vehicle, SHAM + ExT + PVN vehicle or SHAM + Sed + PVN TAK242). †P < 0.05 (2K1C + ExT + PVN vehicle or 2K1C + Sed + PVN TAK242) versus 2K1C + Sed + PVN vehicle.

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  FIGURE 6. ExT or PVN infusion of TAK242 attenuated PVN level of TLR4 of 2K1C hypertensive rats. (A) Immunohistochemistry staining of TLR4 in the PVN. (B) Statistic of TLR4 expression in the PVN. ∗P < 0.05 versus SHAM rats (SHAM + Sed + PVN vehicle, SHAM + ExT + PVN vehicle or SHAM + Sed + PVN TAK242). †P < 0.05 (2K1C + ExT + PVN vehicle or 2K1C + Sed + PVN TAK242) versus 2K1C + Sed + PVN vehicle.

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  FIGURE 7. ExT or PVN infusion of TAK242 attenuated PVN levels of TNF-α and IL-1β mRNA and protein expression of 2K1C hypertensive rats. (A) Immunoreactive bands of TNF-α, IL-1β and β-actin in the PVN. (B) Statistic of TNF-α and IL-1β protein expression. (C,D) Statistic of TNF-α and IL-1β mRNA levels. ∗P < 0.05 versus SHAM rats (SHAM + Sed + PVN vehicle, SHAM + ExT + PVN vehicle or SHAM + Sed + PVN TAK242). †P < 0.05 (2K1C + ExT + PVN vehicle or 2K1C + Sed + PVN TAK242) versus 2K1C + Sed + PVN vehicle.

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  FIGURE 8. ExT or PVN infusion of TAK242 attenuated PVN level of TNF-α of 2K1C hypertensive rats. Immunofluorescence staining of TNF-α in the PVN.

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  FIGURE 9. ExT or PVN infusion of TAK242 attenuated PVN level of IL-1β of 2K1C hypertensive rats. (A) Immunohistochemistry staining of IL-1β in the PVN. (B) Statistic of IL-1β expression in the PVN. (C) Statistic of TNF-α expression in the PVN. ∗P < 0.05 versus SHAM rats (SHAM + Sed + PVN vehicle, SHAM + ExT + PVN vehicle or SHAM + Sed + PVN TAK242). †P < 0.05 (2K1C + ExT + PVN vehicle or 2K1C + Sed + PVN TAK242) versus 2K1C + Sed + PVN vehicle.

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  FIGURE 10. The schematic showing the mechanism by which exercise training attenuates hypertension. 2K1C induced hypertension increases TLR4/MyD88/NF-κB signaling in the PVN, which results in the overloads of PICs, causes sympathoexcitation and eventually accelerate the progression of hypertension. ExT can reverses this pathophysiological process of hypertension by attenuating TLR4/MyD88/NF-κB signaling in the PVN.