Rapid downregulation of adipose tissue lipoprotein lipase activity on food deprivation: evidence that TNF-α is involved

Wu, Gengshu; Brouckaert, Peter; Olivecrona, Thomas

doi:10.1152/ajpendo.00257.2003

Cited by 36 publications

(27 citation statements)

References 35 publications

(30 reference statements)

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“…Estrogen has a biphasic effect on LPL in adipose tissue, with high doses inhibiting and low doses stimulating LPL (78). IGF-1, cortisol, and TNF-a are known to have inhibitory effects on LPL in adipose tissue (49)(50)(51). In our experimental model, we found no change in LPL activity after 1 or 3 h of incubation with insulin alone, PPARg ligand, TNF-a, cortisol, epinephrine, or IGF-1.…”

Section: Discussionmentioning

confidence: 49%

Gestational and hormonal regulation of human placental lipoprotein lipase

Magnusson-Olsson

Hamark

Ericsson

et al. 2006

Journal of Lipid Research

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The fetal demand for FFA increases as gestation proceeds, and LPL represents one potential mechanism for increasing placental lipid transport. We examined LPL activity and protein expression in first trimester and term human placenta. The LPL activity was 3-fold higher in term (n 5 7; P , 0.05) compared with first trimester (n 5 6) placentas. The LPL expression appeared lower in microvillous membrane from first trimester (n 5 2) compared with term (n 5 2) placentas. We incubated isolated placental villous fragments with a variety of effectors [GW 1929, estradiol, insulin, cortisol, epinephrine, insulin-like growth factor-1 (IGF-1), and tumor necrosis factor-a] for 1, 3, and 24 h to investigate potential regulatory mechanisms. Decreased LPL activity was observed after 24 h of incubation with estradiol (1 mg/ml), insulin, cortisol, and IGF-1 (n 5 12; P , 0.05). We observed an increase in LPL activity after 3 h of incubation with estradiol (20 ng/ml) or hyperglycemic medium plus insulin (n 5 7; P , 0.05).

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Section: Discussionmentioning

confidence: 49%

Gestational and hormonal regulation of human placental lipoprotein lipase

Magnusson-Olsson

Hamark

Ericsson

et al. 2006

Journal of Lipid Research

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“…In humans, rats and mice, prolonged fasting increases oxidant production, oxidative damage and inflammation (Crescimanno et al, 1989;Di Simplicio et al, 1997;Grattagliano et al, 2000;Kondoh et al, 2003;Mårtensson, 1986;Sorensen et al, 2006;Souza Rocha et al, 2008;Wu et al, 2004). In elephant seals, prolonged fasting does not induce oxidative damage or inflammation despite promoting the chronic activation of the renin-angiotensin system (RAS) and increasing circulating cortisol, NADPH oxidase activity, Nox4 protein expression and insulin resistance (Ortiz et al, 2000;Ortiz et al, 2002;Vázquez-Medina et al, 2010;Viscarra et al, 2011a;Viscarra et al, 2011b).…”

Section: Introductionmentioning

confidence: 99%

Prolonged fasting increases purine recycling in post-weaned northern elephant seals

Soñanez‐Organis

Vázquez‐Medina

Zenteno‐Savín³

et al. 2012

Journal of Experimental Biology

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SUMMARYNorthern elephant seals are naturally adapted to prolonged periods (1-2months) of absolute food and water deprivation (fasting). In terrestrial mammals, food deprivation stimulates ATP degradation and decreases ATP synthesis, resulting in the accumulation of purines (ATP degradation byproducts). Hypoxanthine-guanine phosphoribosyl transferase (HGPRT) salvages ATP by recycling the purine degradation products derived from xanthine oxidase (XO) metabolism, which also promotes oxidant production. The contributions of HGPRT to purine recycling during prolonged food deprivation in marine mammals are not well defined. In the present study we cloned and characterized the complete and partial cDNA sequences that encode for HGPRT and xanthine oxidoreductase (XOR) in northern elephant seals. We also measured XO protein expression and circulating activity, along with xanthine and hypoxanthine plasma content in fasting northern elephant seal pups. Blood, adipose and muscle tissue samples were collected from animals after 1, 3, 5 and 7weeks of their natural post-weaning fast. The complete HGPRT and partial XOR cDNA sequences are 771 and 345bp long and encode proteins of 218 and 115 amino acids, respectively, with conserved domains important for their function and regulation. XOR mRNA and XO protein expression increased 3-fold and 1.7-fold with fasting, respectively, whereas HGPRT mRNA (4-fold) and protein (2-fold) expression increased after 7weeks in adipose tissue and muscle. Plasma xanthine (3-fold) and hypoxanthine (2.5-fold) levels, and XO (1.7-to 20-fold) and HGPRT (1.5-to 1.7-fold) activities increased during the last 2weeks of fasting. Results suggest that prolonged fasting in elephant seal pups is associated with increased capacity to recycle purines, which may contribute to ameliorating oxidant production and enhancing the supply of ATP, both of which would be beneficial during prolonged food deprivation and appear to be adaptive in this species.

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“…Prolonged food deprivation also promotes production of superoxide radical (O 2 . -), hydrogen peroxide (H 2 O 2 ) and lipid hydroperoxides that contribute to oxidative damage, inflammation and antioxidant depletion in a variety of terrestrial mammals including humans, rats and mice (Crescimanno et al, 1989;Di Simplicio et al, 1997;Grattagliano et al, 2000;Kondoh et al, 2003;Mårtensson, 1986;Sorensen et al, 2006;Souza Rocha et al, 2008;Wu et al, 2004). Glutathione (GSH; -glutamyl-cysteinyl-glycine) is the most important non-enzymatic endogenous antioxidant in animal cells (Forman et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Prolonged fasting increases glutathione biosynthesis in postweaned northern elephant seals

Vázquez‐Medina

Zenteno‐Savín²,

Forman

et al. 2011

Journal of Experimental Biology

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SUMMARYNorthern elephant seals experience prolonged periods of absolute food and water deprivation (fasting) while breeding, molting or weaning. The postweaning fast in elephant seals is characterized by increases in the renin-angiotensin system, expression of the oxidant-producing protein Nox4, and NADPH oxidase activity; however, these increases are not correlated with increased oxidative damage or inflammation. Glutathione (GSH) is a potent reductant and a cofactor for glutathione peroxidases (GPx), glutathione-S transferases (GST) and 1-cys peroxiredoxin (PrxVI) and thus contributes to the removal of hydroperoxides, preventing oxidative damage. The effects of prolonged food deprivation on the GSH system are not well described in mammals. To test our hypothesis that GSH biosynthesis increases with fasting in postweaned elephant seals, we measured circulating and muscle GSH content at the early and late phases of the postweaning fast in elephant seals along with the activity/protein content of glutamate-cysteine ligase [GCL; catalytic (GCLc) and modulatory (GCLm) subunits], -glutamyl transpeptidase (GGT), glutathione disulphide reductase (GR), glucose-6-phosphate dehydrogenase (G6PDH), GST and PrxVI, as well as plasma changes in -glutamyl amino acids, glutamate and glutamine. GSH increased two-to four-fold with fasting along with a 40-50% increase in the content of GCLm and GCLc, a 75% increase in GGT activity, a two-to 2.5-fold increase in GR, G6PDH and GST activities and a 30% increase in PrxVI content. Plasma -glutamyl glutamine, -glutamyl isoleucine and -glutamyl methionine also increased with fasting whereas glutamate and glutamine decreased. Results indicate that GSH biosynthesis increases with fasting and that GSH contributes to counteracting hydroperoxide production, preventing oxidative damage in fasting seals.

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Rapid downregulation of adipose tissue lipoprotein lipase activity on food deprivation: evidence that TNF-α is involved

Cited by 36 publications

References 35 publications

Gestational and hormonal regulation of human placental lipoprotein lipase

Gestational and hormonal regulation of human placental lipoprotein lipase

Prolonged fasting increases purine recycling in post-weaned northern elephant seals

Prolonged fasting increases glutathione biosynthesis in postweaned northern elephant seals

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