Physiology - Research Publications

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End date: 2021 × Author: Kingwell, Bronwyn × Author: Carey, Andrew × Type: Journal Article ×

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    Plasma Docosahexaenoic Acid and Eicosapentaenoic Acid Concentrations Are Positively Associated with Brown Adipose Tissue Activity in Humans
    Xiang, AS ; Giles, C ; Loh, RKC ; Formosa, MF ; Eikelis, N ; Lambert, GW ; Meikle, PJ ; Kingwell, BA ; Carey, AL (MDPI, 2020-10)
    Brown adipose tissue (BAT) activation is a possible therapeutic strategy to increase energy expenditure and improve metabolic homeostasis in obesity. Recent studies have revealed novel interactions between BAT and circulating lipid species-in particular, the non-esterified fatty acid (NEFA) and oxylipin lipid classes. This study aimed to identify individual lipid species that may be associated with cold-stimulated BAT activity in humans. A panel of 44 NEFA and 41 oxylipin species were measured using mass-spectrometry-based lipidomics in the plasma of fourteen healthy male participants before and after 90 min of mild cold exposure. Lipid measures were correlated with BAT activity measured via 18F-fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT), along with norepinephrine (NE) concentration (a surrogate marker of sympathetic activity). The study identified a significant increase in total NEFA concentration following cold exposure that was positively associated with NE concentration change. Individually, 33 NEFA and 11 oxylipin species increased significantly in response to cold exposure. The concentration of the omega-3 NEFA, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) at baseline was significantly associated with BAT activity, and the cold-induced change in 18 NEFA species was significantly associated with BAT activity. No significant associations were identified between BAT activity and oxylipins.
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    Acute effects of active breaks during prolonged sitting on subcutaneous adipose tissue gene expression: an ancillary analysis of a randomised controlled trial
    Grace, MS ; Formosa, MF ; Bozaoglu, K ; Bergouignan, A ; Brozynska, M ; Carey, AL ; Veiga, CB ; Sethi, P ; Dillon, F ; Bertovic, DA ; Inouye, M ; Owen, N ; Dunstan, DW ; Kingwell, BA (NATURE PORTFOLIO, 2019-03-07)
    Active breaks in prolonged sitting has beneficial impacts on cardiometabolic risk biomarkers. The molecular mechanisms include regulation of skeletal muscle gene and protein expression controlling metabolic, inflammatory and cell development pathways. An active communication network exists between adipose and muscle tissue, but the effect of active breaks in prolonged sitting on adipose tissue have not been investigated. This study characterized the acute transcriptional events induced in adipose tissue by regular active breaks during prolonged sitting. We studied 8 overweight/obese adults participating in an acute randomized three-intervention crossover trial. Interventions were performed in the postprandial state and included: (i) prolonged uninterrupted sitting; or prolonged sitting interrupted with 2-minute bouts of (ii) light- or (iii) moderate-intensity treadmill walking every 20 minutes. Subcutaneous adipose tissue biopsies were obtained after each condition. Microarrays identified 36 differentially expressed genes between the three conditions (fold change ≥0.5 in either direction; p < 0.05). Pathway analysis indicated that breaking up of prolonged sitting led to differential regulation of adipose tissue metabolic networks and inflammatory pathways, increased insulin signaling, modulation of adipocyte cell cycle, and facilitated cross-talk between adipose tissue and other organs. This study provides preliminary insight into the adipose tissue regulatory systems that may contribute to the physiological effects of interrupting prolonged sitting.
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    Skeletal Muscle Insulin Resistance Associated with Cholesterol-Induced Activation of Macrophages Is Prevented by High Density Lipoprotein
    Carey, AL ; Siebel, AL ; Reddy-Luthmoodoo, M ; Natoli, AK ; D'Souza, W ; Meikle, PJ ; Sviridov, D ; Drew, BG ; Kingwell, BA ; Kanzaki, M (PUBLIC LIBRARY SCIENCE, 2013-02-21)
    Emerging evidence suggests that high density lipoprotein (HDL) may modulate glucose metabolism through multiple mechanisms including pancreatic insulin secretion as well as insulin-independent glucose uptake into muscle. We hypothesized that HDL may also increase skeletal muscle insulin sensitivity via cholesterol removal and anti-inflammatory actions in macrophages associated with excess adiposity and ectopic lipid deposition.