Martins, F. O. | bioRxiv Science

bioRxiv2023

Ablation of carotid body activity reverses diabesity by improving white and brown adipose tissue sympathetic innervation and metabolism

Finding novel pathological mechanisms that lead to innovative strategies to treat obesity and its associated illness are critically needed. The carotid bodies (CB) are metabolic sensors whose dysfunction contributes to insulin resistance and glucose intolerance development. Herein, we find that the ablation of CB activity, through resection of carotid sinus nerve (CSN) promotes weight loss and restores metabolic function in high fat (HF) rodents, by increasing WAT basal metabolism and by restoring WAT and BAT sympathetic activation. Moreover, we found that CSN resection rescues adipose tissue sympathetic/catecholamine resistance present in obesity states. Additionally, we found that the CB signals integrated in the paraventricular nucleus of the hypothalamus are decreased in obesity states and that CSN denervation in HF animals restore neuronal activity in this region. By inducing energy expenditure via the increase in WAT and BAT metabolism, CB modulation might be used as a therapeutic target for obesity and dysmetabolism. HighlightsO_LIAblation of carotid body (CB) activity promotes weight loss C_LIO_LICarotid body modulates white and brown adipose tissue metabolism C_LIO_LIAblation of CB activity rescues adipose tissue sympathetic resistance in obesity C_LIO_LICarotid sinus nerve resection restored the altered neuronal activity induced by obesity in the paraventricular nucleus of the hypothalamus C_LI

physiology↗

bioRxiv2023

Chronic intermittent hypoxia induced-dysmetabolism is associated with hepatic oxidative stress, mitochondrial dysfunction and inflammation

The association between obstructive sleep apnea (OSA) and metabolic disorders is well-established but the underlying mechanisms that elucidate this relationship remain incompletely understood. Since the liver is a major organ in the maintenance of metabolic homeostasis, we hypothesize that liver dysfunction plays a crucial role in the pathogenesis of metabolic dysfunction associated with obstructive sleep apnea (OSA). Herein, we explored the underlying mechanisms of this association within the liver. Experiments were performed in male Wistar rats fed with a control or high fat (HF) diet (60% lipid-rich) for 12 weeks. Half of the groups were exposed to chronic intermittent hypoxia (CIH) (30 hypoxic (5% O2) cycles, 8 h/day) that mimics OSA, in the last 15 days. Insulin sensitivity and glucose tolerance were assessed. Liver samples were collected for evaluation of lipid deposition, insulin signaling, glucose homeostasis, hypoxia, oxidative stress, antioxidant defenses, mitochondrial biogenesis and inflammation. Both CIH and HF diet induced dysmetabolism, a state not aggravated in animals submitted to HF plus CIH. CIH aggravates hepatic lipid deposition in obese animals. Hypoxia-inducible factors levels were altered by these stimuli. CIH decreased the levels of oxidative phosphorylation complexes in both groups and the levels of SOD-1. HF diet reduced mitochondrial density and hepatic antioxidant capacity. CIH and HF diet produced alterations in cysteine-related thiols and pro-inflammatory markers. The results obtained suggest that hepatic mitochondrial dysfunction and oxidative stress, leading to inflammation, may be significant factors contributing to the development of dysmetabolism associated with OSA.

physiology↗