Significance of increase in glucose 6‐phosphatase activity in brown adipose cells of cold‐exposed and starved mice

Watanabe, Jun; Kanamura, Shinsuke; Tokunaga, Hitoo; Sakaida, Minoru; Kanai, Kazuo

doi:10.1002/ar.1092190108

Cited by 10 publications

(12 citation statements)

References 32 publications

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“…We concluded that the simultaneous increase in the two enzyme activities in the tissues of cold-exposed animals is probably related to "thermogenesis by substrate (futile) cycle between G6P and glucose" (Watanabe et al, 1987). As revealed in the present study, the increase in the two enzyme activities by cold-exposure was inhibited by sectioning of nerve fibers distributed to brown adipose tissues.…”

Section: Discussionsupporting

confidence: 66%

Neuronal regulation of substrate cycle between glucose 6‐phosphate and glucose in brown adipose tissues of cold‐exposed mice

et al. 1990

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The increase in both glucose 6-phosphatase and hexokinase activities in brown adipose tissues of cold-exposed mice probably relates to thermogenesis by the substrate cycle between glucose 6-phosphate and glucose (Watanabe et al.: Anatomical Record 219:39-44, 1987). To clarify the factors causing the simultaneous increase, we examined biochemically the effects of uni- or bilateral surgical denervation of brown adipose tissues, of adrenalectomy, or of streptozotocin injection on the increase in the two activities in the tissues of cold-exposed mice. Further, the effects of denervation on the increase were also examined histochemically. The simultaneous increase in the two activities was inhibited in the denervated tissues of cold-exposed animals in biochemical and histochemical experiments. However, the increase in the activities was not inhibited in the tissues of animals exposed to cold after adrenalectomy or streptozotocin injection. The results suggest strongly that the activation of the substrate cycle in brown adipose tissues of cold-exposed mice is caused by a transmitter released from sympathetic nerve endings, probably norepinephrine.

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Section: Discussionsupporting

confidence: 66%

Neuronal regulation of substrate cycle between glucose 6‐phosphate and glucose in brown adipose tissues of cold‐exposed mice

et al. 1990

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“…ductus epididymis (280) (19), seminal vesicle (270) (18). and brown adipose tissue (259.7) (43). The high G6Pase activity in these organs is related to glucose (or fructose) release into the blood, aqueous humor, epididymal fluid, or seminal fluid.…”

Section: Discussionmentioning

confidence: 99%

Significance of high glucose-6-phosphatase activity in rat oviduct epithelium.

Asaka

Watanabe²,

Amatsu³

et al. 1993

J Histochem Cytochem.

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To study the origin of glucose in the oviduct fluid, we cytochemidy examined gIucose-6-phasphatase (G6Pase) activity in rat oviduct. The activity in the whole oviduct was also assayed biochemically. During proestrous, estrous, and metestrous phases, staining reaction for the activity was moderate in the epithelium of the caudal isthmus (Cd) and uterotubal junction (UJ), whereas it was weak in that of the ampulla (A) and cephalic isthmus (CeI). In the diestrous phase, staining reaction in the epithelium of CaI and UJ became strong although it remained weak in that of A and CeI. Reaction product for the activity was localized in the endoplasmic reticulum and nudear envelope of all cell types in the epithelium. The amount of reaction product in secretory cells was small to moderate in CaI and UJ, and small

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“…In rats exposed to low temperatures, HK activity was 1.15-and 1.17-fold higher in cardiac and gastrocnemius muscles respectively [51]. The exception in mammals was observed in the thermogenic brown adipose tissue of mice, where the increase in HK activity was between 1.9-and 2.5-fold [52,53].…”

Section: Introductionmentioning

confidence: 94%

Characterization of non-cytosolic hexokinase activity in white skeletal muscle from goldfish (Carassius auratus L.) and the effect of cold acclimation

Santos

Diniz

Galina³

et al. 2010

Bioscience Reports

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HK (hexokinase) is an enzyme involved in the first step in the glucose metabolism pathway, converting glucose into G6P (glucose 6-phosphate). Owing to the importance of skeletal muscle for fish swimming and acclimation processes, we used goldfish (Carassius auratus L.) white muscle in order to investigate subcellular distribution and kinetics of HK. In this study, we report that HK activity is predominantly localized in the mitochondrial fraction [NC-HK (non-cytosolic HK)] in goldfish white muscle. Studies of the kinetic parameters revealed that the Km (Michaelis-Menten constant) for glucose was 0.41±0.03 mM and that for mannose was 3-fold lower, whereas the affinity for fructose was too low to be measured. The Km for ATP was 0.88±0.05 mM, whereas no activity was observed when either GTP or ITP was used as a phosphate donor. A moderate inhibition (20-40%) was found for ADP and AMP. Similar to mammalian HK, G6P and glucose analogues were able to promote an inhibition of between 85 and 100% of activity. Here, we found that acclimation of goldfish at 5°C promoted a 2.5-fold increase in NC-HK compared with its counterpart acclimated at 25°C. However, cytosolic HK activity was not altered after thermal acclimation. In summary, our results suggest that the goldfish has a constitutive NC-HK that shows some similarities to mammalian HK-II and, curiously, may play a role in the broad metabolic changes required during the cold acclimation process.

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Significance of increase in glucose 6‐phosphatase activity in brown adipose cells of cold‐exposed and starved mice

Cited by 10 publications

References 32 publications

Neuronal regulation of substrate cycle between glucose 6‐phosphate and glucose in brown adipose tissues of cold‐exposed mice

Neuronal regulation of substrate cycle between glucose 6‐phosphate and glucose in brown adipose tissues of cold‐exposed mice

Significance of high glucose-6-phosphatase activity in rat oviduct epithelium.

Characterization of non-cytosolic hexokinase activity in white skeletal muscle from goldfish (Carassius auratus L.) and the effect of cold acclimation

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