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

Abstract

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.

Circular RNA Expression Profiling and Selection of Key Circular RNAs in the Hypothalamus of Heat-Acclimated Rats

“…Prolonged heat exposure resulted in a prominent decrease of Tre in the HA group (Figure 1C). These findings are consistent with those of earlier studies conducted on HA rats (Dervisevik et al, 2011; Nakagawa et al, 2016).…”

“…Rats were randomly distributed into HA or C group. HA group was maintained in chamber temperature of 35 ± 1°C with a relative humidity of 55 ± 5% 2 h daily for 30 days to induce homeostasis and their body weight Tre changes were monitored (Dervisevik et al, 2011; Domazetovska et al, 2011; Alexander-Shani et al, 2017). Tre was measured under the arousal condition of food and water ad libitum .…”

“…Heat acclimation results in a multitude of positive adaptations, including elevated whole-body sweat rate and body plasma volume in conjunction with reduced core temperature and heart rate (Schwimmer et al, 2004; Dervisevik et al, 2011). Hypothalamus is a portion of the brain which acts as a temperature-regulating center; the hypothalamic preoptic area (POA) is the primary thermoregulatory region, while other regions of the hypothalamus take part in the maintenance of the afferent and efferent neural pathways, assisting in the governing of core and skin temperature by regulating the surrounding thermo effectors.…”

Glucose Metabolism and Dynamics of Facilitative Glucose Transporters (GLUTs) under the Influence of Heat Stress in Dairy Cattle

“…All these physiological, biochemical, and molecular responses make the animal survive in a harsh and stressful environment [14]. The study performed in mice showed that heart glucose level changes as a response to heat stress within a different period (12 and 24 h) of exposure to heat stress [15]. Besides, the study performed in chicken revealed that the apical glucose absorption in the jejunum is elevated to compensate for the glucose level in blood during heat stress [16].…”

Influence of Hyperthermic Environmental Temperature on Adenosine Deaminase Activity in Serum and Lymphoid Organs of Wistar Rats

“…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 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 [21].…”