Aerobic exercise produces changes in plasma IL-6 but not IL-1b in four-beat gaited horses

Abstract

Exercise is an important stressor and is correlated with cytokine production in several tissues. There is little information about changes in interleukin (IL)-6 and IL-1b in four-beat gaited horses during a typical aerobic exercise challenge. The objective of this research was to characterise changes in plasma IL-6, IL-1b, cortisol and other blood biomarkers in four-beat gaited horses after a marcha simulation test. We subjected 12 fit horses (approximately 5 years old and 390 kg) to the marcha simulation test (MST) (i.e. a 10 min warm-up, 30 min at marcha and 15 min cool down). Blood samples were collected before the MST, immediately after the MST and 15 and 120 min after the MST (i.e. recovery). Results were analysed with One Way Repeated Measures ANOVA and a Tukey tests with P≤0.05 and Pearson correlation test. The highest value of plasma IL-6 was observed immediately after MST (6.85 pg/ml) (P≥0.05). IL-1 and cortisol did not change (P≥0.05). However, creatine kinase (CK) and aspartate aminotransferase, nonesterified fatty acid (NEFA), glycerol, total cholesterol and glucose were elevated immediately after the MST and at 15 min after the MST (P≤0.05). No change was observed in alanine aminotransferase and triglycerides (P>0.05). Medium correlation was observed between NEFA and glycerol (R=0.64) and glycerol and triglycerides (R=0.50). In conclusion, an increase in IL-6 immediately that occurred after marcha simulation test was associated with elevated concentrations of several energetic metabolites (NEFA, glycerol and glucose). This metabolic adaption may contributed to the horses’ performance during their typical aerobic exercise and was not associated with significant elevation in IL-1b, CK, and cortisol in healthy trained four-beat gaited horses.

Use of oil-rich diet for gaited horses during physical training

“…The NEFA and triglyceride levels before the testing were similar to those described for fasting Marchador horses (NEFA: ~0.025 mmol/ml; triglycerides: ~32.0 mg/dl) (Ferreira et al 2017). However, in the supplemented group, NEFA levels increased while triglyceride levels decreased compared to the concentrations measured before the testing or in the control group, in addition to those described in the literature (Ferreira et al 2015). The results of this experiment are similar to others reported in the literature, which indicate a reduction in triglyceride levels and an increase in NEFA levels, but differ in terms of total cholesterol (Gleenen et al 1999).…”

“…Dietary fat supplementation and its effects on equine erythrocytes and leukocytes have not yet been clearly described in the literature. The results of this experiment indicated that erythrocyte counts in the non-supplemented group, both before and throughout the experiment, were below the previously described levels (Ferreira et al 2015). However, the dietary supplementation raised the erythrocyte counts to levels similar to those reported in the literature for Campolina and Mangalarga Marchador horses (Ferreira et al 2015), while the leukocyte levels in all the animals of this experiment were within the range described by those authors.…”

“…In racehorses, supplementation with oil elevated plasma lipase activity and muscle antioxidant capacity, but did not increase muscle glycogen and triglyceride levels (Orme et al 1997). In contrast, gaited horses show increased NEFA and triglyceride levels during and immediately after exercise (Ferreira et al 2015), similar to what has been described for other equine sport disciplines (Kronfeld 1996;Orme et al 1997). In the latter disciplines, which are typically aerobic, the increased availability of fats in feed can support athletic performance because they provide high-energy sources and antioxidant capacity in the blood of horse athletes.…”

Effects of supplementation with combination of polyunsaturated oils in diet of horses in maintenance and during marcha training

“…During aerobic exercise, [NEFA] increase after the exercise test (1) , and previous aerobic exercise may promote a much early increase in [NEFA] in exercised horses (17) , which is important to horses that do sports of many challenges in short periods, like marcha gaited championships and helpers in "vaquejada". In four-beat gaited horses submitted to 30 min of marcha gait competition, the [NEFA] ranged from ~110 mmol/mL in fasting pre-test, to ~880 mmol/mL after 15 minutes; then it returned to ~270 mmol/mL after 120 minutes after the end of the gait competition (18) . In contrast, in well trained Thoroughbreds supplemented with fat or in the control group, the [NEFA] after overnight fasting were ~300 mmol/mL and ~200 mmol/mL, respectively, and during recovery, the [NEFA] was higher in the supplemented group (~300 mmol/mL) than in the control group (~220 mmol/mL) (19) , showing different adaptation in these groups.…”

“…Variation in glycerol concentration has some relation with the exercise level and how horses do recovery of their muscles' fat storages. Some researchers found that during aerobic exercise competition (gait), the glycerol content increased from ~49 mg/L, in the pre-test, to ~368 mg/L after 15 minutes of gait, and decreased to ~83 mg/L after 120 minutes (18) . It was different from the behavior observed in intense exercise that glycerol ranged from ~30 mg/L, in rest, to ~45 mg/L after exercising (gallop) and it was ~100 mg/L during recovery (19) .…”