Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB190

Poster Communications

Plasma oxytocin level is enhanced by acute high-intensity interval exercise in men

H. Tsukamoto1,2, N. D. Olesen3, L. G. Petersen3,4, T. Suga2, H. Sørensen3, H. Niel3, S. Ogoh5, N. H. Secher3, T. Hashimoto2

1. University of South Wales, Pontypridd, United Kingdom. 2. Ritsumeikan University, Shiga, Japan. 3. University of Copenhagen, Copenhagen, Denmark. 4. University of California, San Diego, California, United States. 5. Toyo University, Saitama, Japan.

Oxytocin (OT) is a neuropeptide released from neurohypophysis and promotes social cognition and brain-related health. Plasma OT is enhanced by acute very high-volume exercise but not by low- to moderate-volume exercise (Hew-Butler et al. 2008). However, acute very high-volume exercise impairs brain function (Grego et al. 2005) whereas cognitive function is improved by acute high-intensity interval exercise (HIIE) (Tsukamoto et al. 2016). Yet, it is unknown whether HIIE affects OT secretion. Arginine vasopressin is structurally similar to OT and is also released from the neurohypophysis and both plasma OT and arginine vasopressin increase in parallel in response to very high-volume exercise (Hew-Butler et al. 2008). Arginine vasopressin is released by high lactate concentration in the hypophysis (Ohbuchi et al. 2010). Previously, we found that repeated HIIE diminishes cerebral lactate uptake by muscle glycogen depletion-induced low lactate production (Hashimoto et al. 2018). Thus, we hypothesized that plasma OT would be elevated in response to HIIE by increased brain OT release and evaluated internal jugular venous-arterial differences across the brain for OT (v-a diffOT) at rest and end of repeated HIIE in healthy young men. In addition, we also aimed to determine the relationship between OT and lactate across the brain. Subjects (n = 14, age 24 ± 2 years) performed a HIIE protocol twice (warm-up at 50-60% of maximal workload (Wmax) for 5 min and four 4 min bouts of exercise at 80-90% Wmax interspaced by four 3 min bouts at 50-60% Wmax for a total of 28 min) separated by a 60 min resting period because very high-volume induced plasma OT enhancement is returned to the resting level within 60 min after exercise. Blood samples were obtained from the bulb of the right internal jugular vein and a brachial artery to determine v-a diffOT. Transcranial Doppler determined middle cerebral artery mean blood velocity (MCA Vmean), and the global cerebral blood flow (gCBF) was estimated from changes in MCA Vmean. Brain OT release/uptake balance was estimated as v-a diffOT × gCBF. Jugular venous and arterial plasma OT increased similarly in response to both HIIEs (both P < 0.01), but brain OT release/uptake balance was not affected by HIIE. Nevertheless, the exercise-induced increase in jugular venous OT level correlated to brain OT release/uptake balance (1st HIIE r = 0.75 P < 0.01, 2nd HIIE r = 0.80 P < 0.01). In addition to this, there were significant inverse correlations between high arterial plasma OT level and decreased brain OT release/uptake balance (1st HIIE r = -0.64 P < 0.05, 2nd HIIE r = -0.66 P < 0.01). There were no correlations between brain OT release/uptake balance and cerebral lactate uptake. These results indicate that HIIE enhances plasma OT level regardless exercise condition with low cerebral lactate and probably increases both brain OT release and uptake.

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