Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.9.3.1 (cytochrome oxidase)
8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study was designed to determine the effects of colostral fat on energy metabolism, fat oxidation and glucose homeostasis in newborn pigs maintained during the first 29h of life at thermal neutrality (34 degrees C) or in the cold (21 degrees C). Piglets were intragastric fed normal colostrum (NFC, 6% fat) or colostrum deprived of fat (LFC, less than 1% fat). A total of 21 meals of 15 to 18g colostrum/kg birthweight was given at 65- to 70-min intervals. Feeding NFC resulted in a higher amount of retained fat with the highest value being obtained in the 34 degrees C group (P less than 0.01). Fat oxidation represented 47% of the absorbed fat in NFC-fed piglets at 34 degrees C; it was 4.5 fold higher in piglets fed NFC than in those fed LFC (P less than 0.01), and 1.8 fold higher at 21 degrees C than at 34 degrees C (P less than 0.01). At both temperatures, feeding LFC resulted in a lower energy balance (P less than 0.01), whereas nitrogen balance was not affected by temperature and colostrum treatments. At 29 hours of age, rectal temperature was the lowest in piglets fed LFC at 21 degrees C (P less than 0.05). Postnatal enhancement of fat metabolism in relation to environmental and nutritional conditions was evidenced at the tissue level through an adaptation of lipoprotein lipase and cytochrome oxidase activities, especially in the red rhomboideus muscle and the liver.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Contribution of colostral fat to thermogenesis and glucose homeostasis in the newborn pig. 152 69

We have performed a sequential study on the abundance of the mRNA for uncoupling protein (UCP), subunit II of cytochrome-c oxidase (COII) and lipoprotein lipase in brown adipose tissue during the fetal and postnatal periods. Moreover, we have determined whether these parameters can be modulated by ambient temperature in the early hours after birth, and at which point in development this sensitivity first appears. UCP gene expression in the fetal and neonatal period has particular features when compared with overall mitochondriogenesis (COII mRNA expression) or with the expression of lipoprotein lipase mRNA. There is a specific induction of UCP gene expression between days 18 and 19 of pregnancy followed by a specific increase of UCP gene expression in utero and a further increase after birth. The acquisition of the physiological apparatus capable of the response to UCP and lipoprotein lipase gene expression to the environmental temperature is not achieved until the last day of fetal development. This result suggests that mechanisms of beta-adrenergic modulation of gene expression in brown fat are already established at birth. From an experiment on iopanoic acid treatment of pregnant mothers, it was concluded that iodothyronine 5'-deiodinase activity is not necessary for the expression of the mRNAs for UCP, COII and lipoprotein lipase in the fetus whereas it is necessary for the acquisition of temperature sensitivity to these parameters at birth.
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PMID:Ontogeny and perinatal modulation of gene expression in rat brown adipose tissue. Unaltered iodothyronine 5'-deiodinase activity is necessary for the response to environmental temperature at birth. 217 32

Expression of the gene for the brown-fat specific uncoupling protein thermogenin was investigated in cell cultures by hybridization of isolated RNA with a cDNA clone corresponding to mouse thermogenin. The RNA was isolated 3-4 days after confluence from cells differentiated in culture from precursors isolated from the interscapular brown adipose tissue of 5-week-old mice. Very low thermogenin mRNA levels were found in cells derived from untreated mice, and there was only little effect of added norepinephrine on thermogenin gene expression in these cells. However, in cells derived from hypothyroid (methimazole-treated) mice there was a higher expression of thermogenin, and norepinephrine had a marked augmenting effect on the thermogenin mRNA level in these cells. These effects of thermogenin mRNA levels were specific, in that they contrasted with the effects of hypothyroidism and norepinephrine on the level of other mRNA species in these cells (coding for beta-actin, lipoprotein lipase, cytochrome-c oxidase, and glycerol-3-phosphate dehydrogenase). It was concluded that brown-fat cells in culture can reach a differentiated state, sufficiently advanced that the unique properties of these cells can be expressed, and that thermogenin gene expression (i.e., the level of thermogenin mRNA) is under direct control of norepinephrine.
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PMID:Brown adipocytes differentiated in vitro can express the gene for the uncoupling protein thermogenin: effects of hypothyroidism and norepinephrine. 249 23

Daily injections of either 0.8 or 3.2 mg norepinephrine (NE)/kg for 2 wk failed to stimulate brown adipose tissue (BAT) growth, GDP binding, or cytochrome-c oxidase activity (COA) in Syrian hamsters (Mesocricetus auratus). However, a single injection of 1.6 mg NE/kg produced a small (23%) but significant acute increase in BAT GDP binding without affecting COA. Thus there is some loss of sensitivity to NE with chronic treatment in Syrian hamsters. Unilateral sympathectomy by surgical denervation of the interscapular BAT (IBAT) resulted in decreased GDP binding and COA in the denervated pad. Chronic NE treatment in hamsters with denervated IBAT only partially reversed the denervation-induced decreases in GDP binding and COA. It therefore appears that NE is not solely responsible for the maintenance and stimulation of thermogenic activity and COA in Syrian hamster BAT. Denervation of IBAT also resulted in elevated levels of lipoprotein lipase (LPL) in this tissue, a surprising finding since brown and white adipose tissue LPL activity were both stimulated by chronic NE treatment. Therefore, although NE has a stimulatory effect on LPL activity, the primary influence of the neural input to IBAT on this enzyme is inhibitory. These data exemplify dramatic differences between rats and hamsters in the mechanisms controlling BAT thermogenesis and white and brown adipose tissue LPL activity.
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PMID:Effects of norepinephrine and denervation on brown adipose tissue in Syrian hamsters. 254 10

To investigate the cellular control of the recruitment process in brown adipose tissue, the ability of cholera toxin to influence the differentiation of brown preadipocytes developing in culture was investigated. Stromalvascular cells obtained from the brown adipose tissue of 3-wk-old rats were grown in culture for 6-7 days in the presence or absence of cholera toxin. It was found that cholera toxin treatment decreased the expression of the actin gene (indicating an increased degree of differentiation), while at the same time promoting the expression of the genes coding for the mitochondriogenesis marker cytochrome-c oxidase and for the adipocyte conversion marker lipoprotein lipase (all followed at the mRNA level). Chronic cholera toxin treatment also increased the total amount of protein per cell in culture, and a specific cholera toxin-induced 35-kDa protein was identified. It was concluded that (in contrast to the case suggested for white preadipocytes) cholera toxin treatment of brown preadipocytes may not only affect the activity of catabolic enzymes but may also directly promote the differentiation process, indicating that this process is under beta-adrenergic control in the adapting animal.
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PMID:Effects of cholera toxin on gene expression in brown preadipocytes differentiating in culture. 259 86

The role of insulin and brown adipose tissue (BAT) thermogenesis in metabolic efficiency (ME, the efficiency of body wt gain) was examined in rats with varied basal insulin status. Long-lasting insulin was administered using a protocol that did not alter food intake, yet increased ME in both groups. Half the rats were fed sucrose to stimulate BAT growth and thermogenesis. Insulin overrode the exaggerated decrease in ME in sucrose-fed diabetics, with only partial attenuation in controls. Interscapular BAT (IBAT) lipoprotein lipase activity was decreased in diabetic rats, restored by insulin treatment, and not affected in controls. Sucrose-fed diabetics and controls had their IBAT sham or bilaterally surgically denervated. Insulin decreased the thermogenic potential of BAT [cytochrome oxidase activity (COA)] in intact controls and diabetics; in the latter, insulin restored COA independent of BAT innervation. We conclude that insulin can increase ME without an associated increase in energy intake, regardless of basal insulin status, both insulin deficiency and excess decrease BAT thermogenic potential (COA), and hyperinsulinemia-induced increases in ME may result from decreased BAT mitochondrial proliferation.
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PMID:Insulin and metabolic efficiency in rats. I. Effects of sucrose feeding and BAT axotomy. 302 8

Despite long-standing observations of a whole-body thermogenic effect of glucagon, the role of glucagon in activating thermogenesis in brown adipose tissue has not often been studied. We investigated the ability of administered glucagon to produce alterations in brown adipose tissue similar to changes produced by accepted stimuli of brown fat activity: cold, norepinephrine, and overfeeding. Eighteen days of glucagon injections (1 mg/kg) to male Sprague-Dawley rats produced, relative to saline-injected controls, decreases in feed efficiency and increases in brown adipose tissue weight, protein content, DNA content, and mitochondrial mass as reflected in cytochrome oxidase activity. The observed changes were similar, though of lesser magnitude, to changes produced in these same parameters induced by administration of norepinephrine (250 micrograms/kg) for a positive control group. Four days of glucagon administration (1 mg/kg) produced increases in specific activity of cytochrome oxidase and lipoprotein lipase. After 8 days of glucagon administration, changes in whole-pad activity similar to those seen with 18 days of administration were present. Glucagon also increased whole-pad lipoprotein lipase activity after 4 and 8 days. Surgically denervated interscapular brown adipose tissue retained its ability to respond to exogenous glucagon, though the magnitude of the response was diminished. Guanosine 5'-diphosphate (GDP) binding to brown adipose tissue mitochondria was measured as an assessment of functional state after 5 days of glucagon (1 mg/kg). There was an increase in GDP binding relative to controls whether expressed as picomoles per milligram mitochondrial protein or nanomoles per pad.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glucagon stimulation of brown adipose tissue growth and thermogenesis. 302 65

The consequences of hyperlipidic feeding on interscapular brown adipose tissue (IBAT) activity were examined in the cold-acclimated rat. Male Osborne-Mendel rats (7 weeks old) were exposed for 10 weeks at either 28 or 5 degrees C. The rats were fed a semipurified diet (normal fat (NL): 5% lard; high fat (HL): 54% lard) for the last 9 weeks. IBAT weight was greater in HL than in NL rats. This increase was entirely due to accumulation of neutral lipids. Among different IBAT components (proteins, DNA, phospholipids) no variations were observed in HL 28 degrees C rats. HL diet did not modify lipoprotein lipase and cytochrome oxidase activities, but an increase in purine nucleotide binding (taken as an index of thermogenic activity) was observed in HL 28 degrees C rats. Cold acclimation led to comparable stimulation in NL and HL rats. The calorigenic effect of norepinephrine in vivo was not modified by HL diet. Study of arteriovenous differences showed that IBAT fatty acid and glycerol release by norepinephrine was slightly increased in HL 28 degrees C rats. No effect of HL diet was observed at 5 degrees C. These results indicate that HL feeding leads to a moderate increase in the IBAT thermogenic capacity of Osborne-Mendel rats. HL diet does not modify the normal development of nonshivering thermogenesis when rats are kept in a cold environment.
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PMID:Thermogenesis and brown adipose tissue activity in high fat fed Osborne-Mendel rats. 315 Nov 44

Serum prolactin (PRL) decreases in Syrian (Mesocricetus auratus) and Siberian (Phodopus sungorus sungorus) hamsters following short-photoperiod exposure. Both species also exhibit short-photoperiod-induced changes in body and lipid mass, but in opposite directions; Syrian hamsters increase and Siberian hamsters decrease their body weight, changes reflected nearly exclusively in their carcass lipid content. The purpose of these experiments was to determine whether the photoperiod-induced changes in PRL were responsible for the seasonal changes in energy balance in Syrian and Siberian hamsters by using the strategy of experimentally producing serum PRL levels opposite to those normally associated with the photoperiod in which the animals were housed. In long photoperiods serum PRL was reduced to short-day levels by subcutaneous (s.c.) CB-154 (bromoergocryptine, a dopamine agonist) injections. In short photoperiods, serum PRL was elevated to long-day levels in Syrian hamsters by ectopic pituitary explants, and in Siberian hamsters, serum PRL was elevated by chronic s.c. infusions of ovine PRL (oPRL). In both species, manipulations of serum PRL did not affect food intake, carcass composition, or the wet weight of various white and brown adipose tissue pads (WAT and BAT, respectively). Body weight increased in CB-154-treated Syrian hamsters and decreased in Siberian hamsters, an effect partially reversed by coadministration of oPRL in Syrian, but not Siberian, hamsters. Thus, lowering serum PRL to short-day levels in long-day-housed hamsters of both species mimicked the directional change in body weight appropriate for each species when they are exposed to short days. This effect of CB-154 on body weight may be a result of some as yet unidentified effect of dopaminergic stimulation on overall growth since 1) these changes in body weight were not reflected as changes in lipid mass, as occurs naturally following short-day exposure for each species, and 2) neither species exhibited a reciprocal change in body weight when serum PRL was experimentally elevated in short days. Alternatively, it may be that once the energetic responses to short-day exposure have been fully expressed, the ability of PRL to stimulate the target sites of action for PRL for these responses may be decreased. BAT protein content, cytochrome oxidase activity (measures of metabolic growth of this tissue), and retroperitoneal total and specific lipoprotein lipase (LPL) activities were increased by CB-154 treatment in Syrian hamsters.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Are the short-photoperiod-induced decreases in serum prolactin responsible for the seasonal changes in energy balance in Syrian and Siberian hamsters? 344 32

Metabolic changes associated with sustained 48-hr shivering thermogenesis were studied in piglets maintained at 34 (thermoneutrality) or 25 degrees C (cold) between 6 and 54 hr of life. Despite their high shivering activity and elevated heat production, cold-exposed piglets exhibited a slightly lower rectal temperature than thermoneutral animals (-1.1 degrees C; P < 0.01) at the end of the treatment. The enhancement of heat production and shivering activity were associated with a decrease in muscle glycogen (-47%; P < 0.05) and total lipid content (-23%; P < 0.05), a reduction of blood lactate levels (P < 0.05) and an enhancement of muscle cytochrome oxidase activity (+20%; P < 0.05) which suggests that muscle oxidative potential was increased by cold exposure. Potential for capturing lipids (lipoprotein lipase activity) was also higher in the red rhomboideus muscle (+71%; P < 0.01) and lower in adipose tissue (-58%; P < 0.01) of the cold-exposed piglets. Measurements performed at the mitochondrial level show no changes in rhomboideus muscle, but respiratory capacities (state IV and FCCP-stimulated respiration) and intermyofibrillar mitochondria oxidative and phosphorylative (creatine kinase activity) capacities were enhanced in longissimus dorsi muscle (P < 0.05). These changes may contribute to provide muscles with nonlimiting amount of readily oxidable substrates and ATP necessary for shivering thermogenesis. A rise in plasma norepinephrine levels was also observed during the second day of cold exposure (P < 0.05).
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PMID:Metabolic changes associated with sustained 48-hr shivering thermogenesis in the newborn pig. 884 May 9


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