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Glycogen metabolism in β-cells may affect downstream metabolic pathways controlling insulin release. We examined glycogen metabolism in human islets and in the rodent-derived INS-1 832/13 β-cells and found them to express the same isoforms of key enzymes required for glycogen metabolism. Our findings indicate that glycogenesis is insulin-independent but influenced by extracellular glucose concentrations. Levels of glycogen synthase decrease with increasing glucose concentrations, paralleling accumulation of glycogen. We did not find cAMP-elicited glycogenolysis and insulin secretion to be causally related. In conclusion, our results reveal regulated glycogen metabolism in human islets and insulin-secreting cells. Whether glycogen metabolism affects insulin secretion under physiological conditions remains to be determined. [ABSTRACT FROM AUTHOR]

Serotonin (5-HT) is a biogenic monoamine that functions both as a neurotransmitter and a circulating hormone. Recently, the metabolic effects of 5-HT have gained interest and peripheral 5-HT has been proposed to influence lipid metabolism in various ways. Here, we investigated the metabolic effects of 5-HT in isolated, primary rat adipose cells. Incubation with 5-HT suppressed β-adrenergically stimulated glycerol release and decreased phosphorylation of protein kinase A (PKA)-dependent substrates, hormone sensitive lipase (Ser563) and perilipin (Ser522). The inhibitory effect of 5-HT on lipolysis enhanced the anti-lipolytic effect of insulin, but sustained in the presence of phosphodiesterase inhibitors, OPC3911 and isobuthylmethylxanthine (IBMX). The relative expression of 5-HT1A, -2B and -4 receptor class family were significantly higher in adipose tissue compared to adipose cells, whereas 5-HT1D, -2A and -7 were highly expressed in isolated adipose cells. Similar to 5-HT, 5-HT2 receptor agonists reduced lipolysis while 5-HT1 receptor agonists rather decreased non-stimulated and insulin-stimulated glucose uptake. Together, these data provide evidence of a direct effect of 5-HT on adipose cells, where 5-HT suppresses lipolysis and glucose uptake, which could contribute to altered systemic lipid- and glucose metabolism. [ABSTRACT FROM AUTHOR]

Background: A novel coronavirus, SARS-CoV-2 (known as COVID-19), spread rapidly around the world, affecting all and creating an ongoing global pandemic. Across the United States, Latinx and Indigenous populations have been disproportionately affected by COVID-19 cases and death rates. An examination of the perceptions and beliefs about the spread of the virus, COVID-19 testing, and vaccination amongst racial-ethnic minority groups, specifically Latinx and Indigenous Latin American immigrant communities, is needed to alleviate the widespread disparity in new cases and deaths.Methods: This study was carried out from August 2020 to January 2021 and used community-based participatory research to engage community partners and build the capacity of community health workers (i.e., promotores de salud) and pre-medical and medical students in conducting qualitative research. The objective of the study was to examine the structural and social determinants of health on perceptions of the coronavirus, its spread, and decisions around COVID-19 testing and vaccination. Data collection included ethnography involving observations in public settings and focus groups with members of Latinx and Indigenous Mexican farm-working communities in the Eastern Coachella Valley, located in the Inland Southern California desert region. A total of seven focus groups, six in Spanish and one in Purépecha, with a total of 55 participants were conducted. Topics covered include perceptions of the coronavirus and its spread, as well as COVID-19 testing and vaccination.Results: Using theme identification techniques, the findings identify structural and social factors that underly perceptions held by Latinx and Indigenous Mexican immigrants about the virus and COVID-19, which, in turn, shape attitudes and behaviors related to COVID-19 testing and vaccination. Common themes that emerged across focus groups include misinformation, lack of trust in institutions, and insecurity around employment and residency.Conclusions: This immigrant population is structurally vulnerable to historical and present-day inequalities that put them at increased risk of COVID-19 exposure, morbidity, and mortality. Study findings indicate a significant need for interventions that decrease structural vulnerabilities by addressing issues of (dis)trust in government and public health among this population. [ABSTRACT FROM AUTHOR]