Plasma from exercised rats administered to sedentary rats induces systemic and tissue inflammation

Abstract

Recent studies have consistently supported the active role of blood in mediating biochemical and physiological tissue adaptations. However, no study has investigated the possible contribution of circulating factors in an exercise setting. The aim of the study was to investigate the role of circulating factors in exercise adaptations by chronically administering to sedentary animals blood plasma collected from acutely exercised animals. Phase 1: Blood plasma was collected from rats that swam to exhaustion and from sedentary rats. Phase 2: Other rats were divided into two groups (n = 20 per group): the first group involved rats that were injected intravenously with blood plasma originating from rats that previously swam to exhaustion, the second group consisted of rats that were injected intravenously with blood plasma originating from sedentary rats. Tail‐vein injections (2 mL/kg) were performed daily for 21 consecutive days. Inflammatory markers (C‐reactive protein, interleukins‐1α, 2, 6, 8, 10 and tumor necrosis factor‐a) were measured in blood plasma, muscle, and adipose tissue. Sedentary rats administered with plasma from exercised rats had significantly higher levels in all inflammatory markers measured in blood, skeletal muscle and adipose tissue, compared to the sedentary rats administered with resting plasma. Our data demonstrate that administration of “exercised” blood to sedentary rats induced inflammation in plasma, muscle and adipose tissue. Exercise adaptations are not solely due to intrinsic processes in muscle or adipose tissue. Blood factors also play a crucial role in mediating signals for tissue adaptations.

Nicotinamide riboside supplementation dysregulates redox and energy metabolism in rats: Implications for exercise performance

“…Rats swam individually in deep water tanks at a water temperature of 34°C. Rats were familiarized using a modified protocol of our group (Goutianos et al., ; Veskoukis et al., ). The familiarization protocol lasted 11 consecutive days (starting from day 11 of the experiment), and the daily swimming time was 5 min.…”

Chronic administration of plasma from exercised rats to sedentary rats does not induce redox and metabolic adaptations

“…Rats were familiarized with swimming for 4 consecutive days [26]. The daily swimming duration was 10 min with various loads attached on the base of their tails, ranging from 0% to approximately 4% of their body weight.…”

“…This is best exemplified by the elegant experimental approaches implemented by different research groups in order to reveal the role of circulating molecules in diverse biological phenomena (e.g., exercise adaptations, healthy aging, longevity). These approaches include the incubation of cells in mediums containing either components or the whole secretome of other cells [6,7], cell or tissue cultures incubated with serum from exercised [8][9][10][11] or calorie-restricted individuals [12][13][14][15], transplantation of white fat from exercised to sedentary animals [16], parabiosis set-ups between transgenic and wild-type exercised animals [17], as well as between young and aged animals [18][19][20][21][22][23][24][25], plasma injection from exercised to sedentary rats [26] and from young to aged animals [25] and, finally, execution of isolated body part or limb exercise protocols [27][28][29][30][31][32]. According to the available data, there is some evidence suggesting that changes in circulating molecules can stimulate the production of factors that subsequently affect other tissues.…”

“…All the aforementioned experimental designs provide valuable information on the role of blood or its constituents, however, each design has some fundamental limitations [e.g., in vitro to in vivo extrapolation (cell culture studies), use of highly invasive techniques (parabiosis studies) and parallel effect of the neural system (isolated body part exercise studies)]. Plasma injection in rodents, although not without limitations, seems to be a rather non-invasive and effective model to study in vivo the effect of circulating factors in tissue and organ adaptations [26,34]. Regarding exercise, and to the best of our knowledge, only one study has used this experimental approach and has reported that plasma injection from exercised rats to sedentary rats induced systemic and tissue inflammation [(i.e., interleukins, tumor necrosis factor alpha (TNF-α) and C-reactive protein (CRP)] [26].…”

“…Plasma injection in rodents, although not without limitations, seems to be a rather non-invasive and effective model to study in vivo the effect of circulating factors in tissue and organ adaptations [26,34]. Regarding exercise, and to the best of our knowledge, only one study has used this experimental approach and has reported that plasma injection from exercised rats to sedentary rats induced systemic and tissue inflammation [(i.e., interleukins, tumor necrosis factor alpha (TNF-α) and C-reactive protein (CRP)] [26]. This may also have important implications in the redox homeostasis of the sedentary rats, since inflammatory and redox processes are strongly interrelated.…”