Abstract
We previously found that acute exercise inhibited the gastric emptying of liquid in awake rats by causing an acid-base imbalance. In the present study, we investigated the involvement of the nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway, vasoactive intestinal peptide (VIP), and corticotropin-releasing factor (CRF) peptide in this phenomenon. Male rats were divided into exercise or sedentary group and were subjected to a 15-min swim session against a load (2.5 or 5% b.w.). The rate of gastric emptying was evaluated after 5, 10, or 20 min postprandially. Separate groups of rats were treated with vehicle (0.9% NaCl, 0.1 mL/100 g, ip) or one of the following agents: atropine (1.0 mg/kg, ip), the NO non-selective inhibitor Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME; 10.0 mg/kg, ip), or the selective cGMP inhibitor 1H-(1,2,4)oxadiazole[4,3-a]quinoxalin-1-one (ODQ; 5.0 mg/kg, ip), the i-NOS non-specific inhibitor (aminoguanidine; 10.0 mg/kg, ip), the corticotropin-releasing factor receptor antagonist (astressin; 100 µg/kg, ip), or the vasoactive intestinal peptide (VIP) receptor antagonist Lys1, Pro2,5, Arg3,4, Tyr6 (100 µg/kg, ip). Compared to sedentary rats, both the 2.5 and 5% exercise groups exhibited higher (P<0.05) values of blood lactate and fractional gastric dye recovery. Corticosterone and NO levels increased (P<0.05) in the 5% exercised rats. Pretreatment with astressin, VIP antagonist, atropine, L-NAME, and ODQ prevented the increase in gastric retention caused by exercise in rats. Acute exercise increased gastric retention, a phenomenon that appears to be mediated by the NO-cGMP pathway, CRF, and VIP receptors.
Highlights
Regular physical activity has a notable impact on various physiological systems, such as cardiovascular [1] and neuromuscular [2] systems
We recently found that acute high-intensity exercise delayed the gastric emptying (GE) of a liquid test meal in awake male rats, a phenomenon that appears to be related to blood academia [6]
No significant difference was found between groups regarding the following parameters: total body water (TBW), extracellular fluid (ECF), intracellular fluid (ICF), fat-free mass (FFM), fat mass (FM), or body mass index (BMI)
Summary
Regular physical activity has a notable impact on various physiological systems, such as cardiovascular [1] and neuromuscular [2] systems. Especially runners, report gut dysmotility during training and racing. Half have loose stools, and nausea and vomiting frequently occur after hard runs. According to Gil et al [3], 20 to 50% of the athletes that perform high-intensity physical exercise ( those of aerobic nature, such as cycling, marathons, and triathlons) present gastrointestinal complaints, including diarrhea and incontinence; rectal bleeding is frequent [4]. Runners usually take prophylactic medications to minimize some of these disorders. Upper digestive symptoms seem to occur more often in multisport events (e.g., triathlons) [5]. Physical exercise can be both beneficial and harmful for the gastrointestinal tract in a dose-effect relationship between its intensity and health [4]
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