Effect of the acclimation to high environmental temperature on the activity of hepatic glycogen phosphorylase (a+b and a), liver glycogen content and blood glucose level in rats

Mitev, Slavco; Dinevska-Kovkarovska, Suzana; Miova, Biljana

doi:10.1016/j.jtherbio.2005.07.003

Cited by 25 publications

(23 citation statements)

References 17 publications

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“…Besides the well-known hepatic glycogenolysis in the STHA [6][7][8], we also observed intensive glycogenolysis at the level of heart Glk stores (Fig. 1).…”

Section: Short-term Heat Acclimationsupporting

confidence: 64%

“…Several other investigations suggest that the acclimation-induced augmentation of constitutive Glk is accompanied by parallel enzymatic changes which may affect the rate of glycogenolysis [11]. Some of these metabolic features, characteristic of the heart during heat acclimation are due to a sustained low thyroxin level [3,6,8,11,[26][27][28]. Several other investigations have reported that hypothyroidism is also associated with a dramatic loss in the activity of heart PFK-1, as well as PFK-2 activity and fructose 2,6 bisphosphate level [29][30][31].…”

Section: Long-term Heat Acclimationmentioning

confidence: 99%

“…In this sense, there is an enhancement of the metabolic machinery to elevate the energy potential of heat-acclimated organism which is accompanied by a decrease of the rate of the whole body metabolism [4,5]. Metabolic changes which are most evident during heat acclimation are: energy sparing, which is manifested as a rebound of liver glycogen (Glk) in rats [6][7][8] and hamsters [9] (as a result of increased activity of enzymes involved in a direct Glk synthesis), and decreased glucose (Glu) production [6][7][8]. As is the case with the liver, heat acclimation produces favorable adaptations in mechanical and metabolic aspects of the heart performance, such as: twofold greater heart Glk level, increased b-adrenergic sensibility, lowered heart rate and greater stroke volume.…”

Section: Introductionmentioning

confidence: 99%

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Heat acclimation-induced changes in heart glycogen/glucose metabolism in rats

et al. 2011

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Based on the observation that heat acclimation is a slowly developing response, evoked by continuous exposure to moderate heat, we investigated the time-dependent acclimatory changes of heart glycogen metabolism. Cardiac levels of key carbohydrate-related enzymes and substrates were studied in the function of the duration of short-term (STHA; 6, 12, 24 and 48 h) and long-term heat acclimation (LTHA; 7, 14, 21 and 30 days) to high environmental temperature (35 ± 1°C). The changes in heart glycogen metabolism during STHA could be separated in two phases: up to 12 h exposure, where significant decrease of the heart glycogen (Glk), glucose-6-phosphate (G6P), hexokinase (HK) activity as well as increase of heart glucose was observed; and from 24 to 48 h exposure, manifested with elevation of Glk, Glu, glycogen phosphorylase a (GPa), phosphofructokinase (PFK) and HK activities. The metabolic changes in the period of LTHA could also be seen as separate phases: in a period of 7-14 days of heat exposure there was an increase of heart Glk, Glu, G6P, HK, as well as a decrease of GPa and PFK, while in the period of 21-28 days there was more intensive rebound of Glk and G6P, increase of GPa activity and non-significant changes of Glu, HK and PFK. The results obtained have showed that acclimation to moderate hyperthermic environment has caused significant changes in examined parameters which differ depending on duration to the exposure: intensive stress-induced glycogenolytic and glycolytic processes in the period of STHA and intensive energy sparing, manifested by Glk deposition in the period of LTHA.

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“…Besides the well-known hepatic glycogenolysis in the STHA [6][7][8], we also observed intensive glycogenolysis at the level of heart Glk stores (Fig. 1).…”

Section: Short-term Heat Acclimationsupporting

confidence: 64%

Section: Long-term Heat Acclimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Heat acclimation-induced changes in heart glycogen/glucose metabolism in rats

et al. 2011

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“…The animals were divided into two groups (7 animals per group): control and heat exposed (experimental) group. The control group was kept at room temperature (20 ± 2 o C), while the experimental group was continuously exposed for 4 consecutive days to moderately high ambient temperature (35 ± 1 o C) in a special heat chamber with regulated air temperature and air humidity of 30-40%, as previously described [12,13]. Both groups were kept under a 12:12 h light-dark regime, having free access to standard laboratory food and water.…”

Section: Animals and Experimental Protocolmentioning

confidence: 99%

“…The specifi c temperature for the experimental group (35 ± 1 o C) was chosen based on some previous investigations [13], where it was established as a moderate high environmental temperature. Furthermore, the climate region of South-Eastern Europe, which we belong to, is considered to have similar air temperatures during the summer months.…”

Section: Animals and Experimental Protocolmentioning

confidence: 99%

The Effect of Moderate Heat on Rat Pituitary ACTH Cells: Histomorphometric, Immunofluorescent and Hormonal Study

et al. 2017

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In areas with moderate continental climate, increased average ambient temperature during the summer represents a stressogenic factor that affects the hypothalamo-pituitaryadrenocortical axis in mammals. Therefore, we wanted to examine the effects of 4 days of constant exposure to moderately elevated ambient temperature (35 ± 1 o C) on the histomorphometric and immunofl uorescent characteristics, as well as on the hormonal secretion of pituitary corticotropes (ACTH) cells in adult male rats. In comparison with the controls kept at 20 ± 2 o C, a signifi cant increase (p<0.05) of the absolute and relative pituitary weight (23.1% and 36.1%, respectively) was registered after exposure to heat. The localization, as well as the shape of the ACTH cells in the heat exposed group was not signifi cantly altered, but their immunopositivity was weaker. After 4 days of heat exposure, a weaker signal confi rmed the relative fl uorescence intensity of the ACTH cells (15.3%, p<0.05). In heat exposed rats, an increase of the cellular and nuclear volumes of immunolabelled ACTH cells and decrease of their volume density (6.9%, 14.3% and 20.0%, respectively; p<0.05) was registered. Observed histomorphometric and immunofl uorescent features of the pituitary ACTH cells were in accordance with the increased (p<0.05) value of plasma adrenocorticotropic hormone (ACTH) by 23.7% compared to the control rats. It can be concluded that the 4-day exposure to moderately elevated ambient temperature intensifi es pituitary ACTH secretion in adult male rats.

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Effects of Environment on Metabolism

Baumgard¹,

Rhoads²

2012

Environmental Physiology of Livestock

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Effect of the acclimation to high environmental temperature on the activity of hepatic glycogen phosphorylase (a+b and a), liver glycogen content and blood glucose level in rats

Cited by 25 publications

References 17 publications

Heat acclimation-induced changes in heart glycogen/glucose metabolism in rats

Heat acclimation-induced changes in heart glycogen/glucose metabolism in rats

The Effect of Moderate Heat on Rat Pituitary ACTH Cells: Histomorphometric, Immunofluorescent and Hormonal Study

Effects of Environment on Metabolism

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