Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB205

Poster Communications

The role of endogenous oxytocin on the anti-stress effect of exercise

S. Arabaci Tamer1, S. Ucem2, M. Guner2, B. Buke2, A. Karakucuk2, N. Yigit2, O. Cevik3, B. Coskunlu4, F. Ercan4, S. SIRVANCI4, B. Yegen1

1. Faculty of Medicine, Department of Physiology, Marmara University, Istanbul, Turkey. 2. Faculty of Medicine, Marmara University, Istanbul, Turkey. 3. Faculty of Medicine, Department of Biochemistry, Adnan Menderes University, Aydin, Turkey. 4. Faculty of Medicine, Department of Histology and Embryology, Marmara University, Istanbul, Turkey.

Exogenously administered oxytocin, which results in suppression of the hypothalamopituiatary-adrenal (HPA) axis1, was proven to possess anti-ulcer effects2. Regular exercise protects gastric mucosa by alleviating stress3, suggesting that the anti-ulcer effects of exercise training might be mediated by endogenous oxytocin via the inhibition of HPA axis. The aim was to investigate the role of endogenous oxytocin in the anti-ulcer impact of exercise on gastric ulcerogenesis. Following the ethical approval, Wistar albino rats were randomly divided as exercise (30 min/day, 5 days/week swimming for 6 weeks) and sedentary groups. On 7th week, under ketamine and chlorpromazine anesthesia (100 and 10 mg/kg, intraperitoneally, ip) rats underwent a laparotomy, and acetic acid (80%; ulcer, n=28) or saline (control; n=28) was applied on serosal surface of stomachs for 1 min. Oxytocin-receptor-antagonist atosiban (0.1 mg/kg/day) or saline was injected ip on the last 4 days before surgery and on 3 days after surgery. On postsurgical 3rd day, anxiety levels were determined using hole-board. Then, on the 4th day gastric serosal blood flow was measured under anesthesia via laser Doppler flowmetry. The rats were euthanised following the withdrawal of blood by cardiac puncture. Using ELISA, serum cortisol levels and gastric levels of 8-hydroxy-2′-deoxyguanosine (8OHDG) and caspase-3 activity were determined. Gastric injury was assessed histologically (hematoxylin & eosin) and immunohistochemical expression of oxytocin was evaluated in the supraoptic nuclei. Statistical analyses were made using ANOVA and Student's t-tests. Compared to sedentary control group, serum cortisol level was increased in the sedentary-ulcer groups (p<0.05), while head-dipping numbers on holeboard were reduced (p<0.05), indicating increased anxiety. Regular exercise depressed cortisol and increased head-dipping number, showing decreased anxiety (p<0.05). When compared with sedentary control group, caspase-3 activity, 8-OHDG levels and gastric damage scores showed significant increases in the sedentary ulcer group (p<0.001), while serosal blood flow was significantly decreased (p<0.05). Swimming exercise elevated serosal blood flow and attenuated ulcer-induced gastric damage score (p<0.05), while atosiban treatment reversed exercise-induced reduction in gastric damage score (p<0.05). Oxytocin expression in supraoptic nucleus showed a tendency to decline in the sedentary ulcer groups (control:1.3±0.4, ulcer: 0.3±0.3), but exercise increased expression above control level (2.5±0.5, p<0.05), while atosiban blunted exercise-induced increase in oxytocin expression (0.7±0.2; p<0.05). These data suggest that exercise reduces anxiety, protects gastric mucosa and supports gastric blood flow by suppressing HPA activity, which appears to involve the upregulation of hypothalamic oxytocin synthesis.

Where applicable, experiments conform with Society ethical requirements