Biology subjects

Pon Velayutham, A. B.

Publications and source records attributed to Pon Velayutham, A. B..

2 recordsLinked to original sources

bioRxiv2024

Establishing reliable blood biomarkers for trimethylamine N-oxide status in rodents: effects of oral choline challenge, dietary choline and fasting conditions

Circulating concentrations of the gut microbial-mammalian metabolite trimethylamine N-oxide (TMAO) is linked to atherosclerosis risk. TMAO biosynthesis begins when dietary choline is converted to trimethylamine (TMA) by gut microbial TMA lyase. TMA is transported to the liver, where flavin-containing monooxygenases convert it to TMAO. While dietary modifications regulate TMAO production, the impact of different intake methods, including oral gavage, dietary supplementation, and conditions such as fasting versus non-fasting, has not been fully explored. Twelve female Sprague-Dawley rats were divided into three diet groups (n = 4 per group): no-choline (0% choline), low-choline (0.08% choline), and high-choline (1% choline). Choline and TMAO fasting and non-fasting blood concentrations, and their kinetics following an acute choline challenge, were assessed before and after a 2-week dietary intervention with the distinct choline dietary levels. Fasting choline was under tight control, with little effect of dietary choline. Non-fasting choline was more variable, with high dietary choline reflected in higher blood choline. Greater levels of dietary choline were reflected in significantly greater levels of TMAO, particularly for non-fasting levels. Kinetic profiling demonstrated additional information regarding the appearance and clearance of these compounds from blood. These results suggest that acute oral choline gavage is likely most suitable for studies targeting acute (direct) inhibitors, whereas a choline-rich diet with assessment of fasting and non-fasting blood levels is more suitable for studying alterations to TMAO production capacity. Future research should examine the impact on atherosclerosis biomarkers and microbiome diversity to deepen the understanding of TMAO regulation and its cardiovascular implications.

biochemistry↗

bioRxiv2021

Activating P2Y1 receptors improves function in arteries with repressed autophagy

ObjectiveThe importance of endothelial cell (EC) autophagy to vascular homeostasis is evolving. Earlier we reported that purinergic 2Y1 receptor (P2Y1-R) activation rejuvenates shearstress induced nitric oxide (NO) generation in bovine aortic endothelial cells that is otherwise compromised after pharmacological and genetic autophagy repression. Here we determined the translational and functional relevance of these findings. Approach and ResultsFirst we assessed translational relevance using older humans and mice that exhibit blunted EC autophagy at rest together with impaired arterial function vs. appropriate controls. Rhythmic handgrip exercise elevated radial artery shear rate similarly in adult and older males for 60-min. Compared to baseline, autophagy initiation, p-eNOSS1177 activation, and NO generation, occurred in radial artery ECs from adult but not older subjects. Regarding mice, indexes of autophagy and p-eNOSS1177 activation were robust in ECs from adult but not older mice in response to 60-min treadmill-running. Next we questioned whether an inability to initiate EC autophagy precipitates arterial dysfunction. Age-associated reductions in intraluminal flow-mediated vasodilation observed in older vs. adult mice were recapitulated in arteries from adult mice by : (i) NO synthase inhibition; (ii) autophagy impairment using 3-methyladenine (3-MA); (iii) EC Atg3 depletion (iecAtg3KO mice); (iv) P2Y1-R blockade; and (v) germline depletion of P2Y1-Rs. Importantly, P2Y1-R activation using 2-methylthio-ADP (2-Me-ADP) improved vasodilatory capacity in arteries from : (i) adult mice treated with 3-MA; (ii) adult iecAtg3KO mice; and (iii) older animals with repressed EC autophagy. ConclusionsArterial dysfunction concurrent with pharmacological, genetic, and age-associated EC autophagy compromise is improved by activating P2Y1-Rs.

physiology↗