Author(s): SIMPSON, A., PILOTTO, A., BROCCA, L., MAZZOLARI, R., ROSIER, B., CARDA-DIÉGUEZ, M., CASAS-AGUSTENCH, P., BESCOS, R., PORCELLI, S., MIRA, A., EASTON, C., HENRIQUEZ, F., BURLEIGH, M., Institution: UNIVERSITY OF THE WEST OF SCOTLAND, Country: UNITED KINGDOM, Abstract-ID: 1378

INTRODUCTION:
Nitric oxide (NO) is a multifunctional signalling molecule, produced by NO synthase (NOS) enzymes or the stepwise reduction of nitrate (NO3-) to nitrite (NO2-) by commensal oral bacteria(1). Exercise training upregulates NOS expression, improving systemic health(2). Physical activity is also associated with oral health in the general population(3). This may be underpinned by actions of oral NO2- producing bacteria which increase oral resilience to acidification, preventing tooth demineralisation(4). We provide novel data exploring the effect of exercise training on the oral microbiome and NO metabolites.
METHODS:
An exercise training and detraining study was used to explore changes to the oral microbiome and systemic and oral NO metabolite levels. Eleven untrained males (age 25±5 years, body mass 64.0±11.2kg, stature 171±6 cm, VO2peak<45ml·min−1·kg−1) underwent 8-weeks of high-intensity interval training (HIIT), followed by 12-weeks of detraining. Samples were collected at baseline, after training and after detraining. The tongue dorsum microbiome was examined using long-read 16S rRNA sequencing. Changes in NO3- and NO2-in saliva, serum and muscle were measured with high-performance liquid chromatography.
RESULTS:
Multiple alterations were seen in the microbiome following changes in activity level (all p≤0.049). These changes were relevant to systemic and oral NO availability. At the genus level, post-HIIT, NO2producing Rothia and Prevotella increased in abundance and Neisseria decreased in abundance. Five of the nine species which increased in abundance post-HIIT demonstrate NO2producing capacity. These were Rothia mucilaginosa, Streptococcus salivarius, Streptococcus parasanguinis, Prevotella salivae and Prevotella melanginogenica. NO3- increased in plasma post-training (Δ 14.15, 95%CI 1.44-26.85uM, p≤0.03) and decreased post-detraining (Δ-9.91, 95%CI -1.10-18.73μM, p≤0.033). NO2- increased in saliva post-training (Δ+78.27, 95%CI 16.21-140.3μM p=0.016) but decreased in plasma (Δ-182.0, 95%CI -20.26343.7nM, p<0.029) and muscle (Δ-0.57, 95%CI -0.250.89 μMol.kg-1, p≤0.002), before returning to baseline post-detraining (both p≤0.011).
CONCLUSION:
Structured exercise training altered the composition of the tongue dorsum microbiome, increasing the abundance of several NO2producing species. While NO3- levels in the muscle and saliva remained unchanged following HIIT, plasma NO3- increased. Exercise training also elevated salivary NO2- while decreasing NO2- levels in the plasma and muscle. These changes did not persist after detraining. When taken together, these results may have implications for general and oral health due to the potential impacts of oral NO2- production on NO availability.

1.Hezel MP, et al. Oral Dis. 2015
2.Nosarev AV, et al. Front Cell Dev Biol. 2015
3.Chan CCK, et al. Front Oral Health. 2023
4.Rosier BT, et al. J Dent Res. 2022.