Fig 1.
Mice were treated with quercetin 30 min before and 12 h after (depending on the experiment), and were submitted to intense acute swimming session. During the swimming session (0–2 h), time spent in swimming behavior and immobility behavior were determined; cytokine production in the soleus and gastrocnemius muscles and glucose and CK levels in blood were assessed immediately after the session (2 h); cytokine production in the spinal cord and oxidative stress in the soleus and gastrocnemius muscles and spinal cord were assessed 2 h after the session (4 h); muscle mechanical hyperalgesia were evaluated 6–48 h after the session; NAG activity was assessed 12 h after the session as part of time-response experiment; glucose and CK levels in blood, MPO and NAG activity (time-response experiment as well as the time period chosen), NFκB activation, COX-2, gp91phox, Nrf2 and HO-1 mRNA expression in the soleus and gastrocnemius muscles and GFAP and Iba-1 mRNA expression in the spinal cord were assessed 24 h after the session.
Fig 2.
Quercetin reduces in a dose-dependent manner intense acute swimming-induced muscle mechanical hyperalgesia and did not affect glucose levels, time spent in swimming behavior or immobility behavior during the intense acute swimming session.
Mice received vehicle (2% DMSO in saline) or quercetin (1–30 mg/kg, i.p.) 30 min before plus reinforcements 12 h after the intense acute swimming session. The intensity of muscle mechanical hyperalgesia was evaluated 6–48 h after the intense acute swimming session (Panel A). Glucose plasmatic levels were determined immediately after and 24 h (peak of the hyperalgesia) after the swimming session (Panel B). Time spent in swimming behavior (Panel C) and immobility behavior (Panel D) were measured during the period of 2 h of the intense acute swimming session in quercetin (30 mg/kg, i.p., 30 min before) and vehicle treated groups. Results are presented as intensity of hyperalgesia (Δ reaction, in grams), glucose (mg/dL of plasma), time spent in swimming behavior and immobility behavior in minutes (Panels A-D) (n = 6 mice per group per experiment, representative of two independent experiments). *P<0.05 compared with naïve and sham groups, #P<0.05 compared with vehicle group, **P<0.05 compared with vehicle and 1 mg/kg groups, ##P<0.05 compared with vehicle, 1 and 3 mg/kg groups, ***P<0.05 compared with vehicle, 1, 3 and 10 mg/kg groups (Two-way ANOVA followed by Tukey’s post hoc).
Fig 3.
Quercetin reduces intense acute swimming-induced increase in MPO and NAG activities in the soleus muscle but not in the gastrocnemius muscle.
Mice were treated with vehicle or quercetin (30 mg/kg, i.p.) 30 min before plus reinforcements 12 h after the intense acute swimming session. MPO (Panels A and B) and NAG (Panels C and D) activities were measured 24 h after the intense acute swimming session. Results are presented as MPO (Neutrophils x 1010) and NAG (Macrophages x 104) activity per milligram of the soleus and gastrocnemius muscles (n = 6 mice per group per experiment, representative of two independent experiments). *P<0.05 compared to the naïve and sham groups, #P<0.05 compared with vehicle group (One-way ANOVA followed by Tukey’s post hoc).
Fig 4.
Quercetin reduces intense acute swimming-induced TNF-α, IL-1β and IL-10 production in the soleus muscle, but not in the gastrocnemius muscle.
Mice were treated with vehicle or quercetin (30 mg/kg, i.p.) 30 min before intense acute swimming session. The TNF-α, IL-1β and IL-10 concentration in the soleus (Panel A) and gastrocnemius (Panel B) muscles were quantified immediately after the end of intense acute swimming session by ELISA. Results are presented as picograms (pg) per 100 mg of soleus and gastrocnemius muscles samples (n = 6 mice per group per experiment, representative of two independent experiments). *P<0.05 compared to the naïve and sham groups, #P<0.05 compared with vehicle group (One-way ANOVA followed by Tukey’s post hoc).
Fig 5.
Quercetin reduces intense acute swimming-induced oxidative stress in the soleus muscle, but not in the gastrocnemius muscle.
Mice were treated with vehicle or quercetin (30 mg/kg, i.p.) 30 min before intense acute swimming session. The ABTS, GSH, NBT and TBARS assays in the soleus (Panels A-D) and gastrocnemius (Panels E- H) muscles were quantified in samples collected 2 h after the end of intense acute swimming session. Results are presented as ABTS assay (nmol of trolox eq/mg), GSH (mmols/mg), NBT reduction (OD/mg of protein) and TBARS (nmol of MDA/mg of protein) of soleus and gastrocnemius muscles (n = 6 mice per group per experiment, representative of two independent experiments). *P<0.05 compared to the naïve and sham groups, #P<0.05 compared with vehicle group (One-way ANOVA followed by Tukey’s post hoc).
Fig 6.
Quercetin reduces intense acute swimming-induced COX-2 and gp91phox mRNA expression in the soleus muscle.
Mice were treated with vehicle or quercetin (30 mg/kg, i.p.) 30 min before plus reinforcements 12 h after the intense acute swimming session. Samples of soleus muscle were collected 24 h after the intense acute swimming session. COX-2 (Panel A) and gp91phox (Panel B) mRNA expression were determined by qPCR. Results are presented as COX-2 and gp91phox mRNA expression (normalized to Gapdh) (n = 6 mice per group per experiment, representative of two independent experiments). *P<0.05 compared to the naïve and sham groups, #P<0.05 compared with vehicle group (One-way ANOVA followed by Tukey’s post hoc).
Fig 7.
Quercetin inhibits NFκB activation and induces Nrf2 and HO-1 mRNA expression in the soleus muscle after intense acute swimming.
Mice were treated with vehicle or quercetin (30 mg/kg, i.p.) 30 min before plus reinforcements 12 h after the intense acute swimming session. NFκB activation (total NFκB/phosphorylated NFκB ratio, Panel A), and Nrf2 (Panel B) and HO-1 (Panel C) mRNA expression in the soleus muscle were assessed 24 h after the intense acute swimming session. Results are presented as NFκB activation (total-p65/phosphotrilated-p65 ratio)/mg of soleus muscle, and Nrf2 and HO-1 mRNA expression (normalized to Gapdh) (n = 6 mice per group per experiment, representative of two independent experiments). *P<0.05 compared to the vehicle treated group (One-way ANOVA followed by Tukey’s post hoc).
Fig 8.
Quercetin reduces intense acute swimming-induced increases in plasmatic concentrations of CK and MyoD mRNA expression in the soleus muscle.
Mice were treated with vehicle or quercetin (30 mg/kg, i.p.) 30 min before plus reinforcements 12 h after the intense acute swimming session. At 2 or 24 h after the intense acute swimming session, blood samples were collected for determination of plasmatic levels of CK (Panel A). Samples of the soleus muscle were collected 24 h after the intense acute swimming session for evaluation of MyoD mRNA expression (Panel B). Results are presented as creatine kinase (total) (U/L of plasma) and MyoD mRNA expression (normalized to Gapdh) (n = 6 mice per group per experiment, representative of two independent experiments). *P<0.05 compared to the naïve and sham groups, #P<0.05 compared with vehicle group (One-way ANOVA followed by Tukey’s post hoc).
Fig 9.
Quercetin reduces intense acute swimming-induced increases in cytokine production, oxidative stress and glial cells activation in the spinal cord.
Mice were treated with vehicle or quercetin (30 mg/kg, i.p.) 30 min before (for cytokine production and oxidative stress determination) plus reinforcements 12 h after the intense acute swimming session (for glial cells activation assessment). Samples of the spinal cord (L4-L6) were collected 2 h after the intense acute swimming session for evaluation of cytokine production (TNF-α, IL-1β and IL-10) (Panel A) and oxidative stress (GSH and TBARS) (Panels B and C). GFAP and Iba-1 mRNA expression in spinal cord samples was determined 24 h after the swimming session (Panels D and E). Results are presented as cytokines (picograms per 100 mg), GSH (mmol/mg) and TBARS (nmol of MDA/mg of protein) of spinal cord samples, and GFAP and Iba-1 mRNA expression (normalized to Gapdh) (n = 6 mice per group per experiment, representative of two independent experiments). *P<0.05 compared to the naïve and sham groups, #P<0.05 compared with vehicle group (One-way ANOVA followed by Tukey’s post hoc).