Effect of estradiol on tissue glycogen metabolism and lipid availability in exercised male rats

Abstract

The effect of 17 beta-estradiol 3-benzoate (10 micrograms.0.1 ml sunflower oil-1.100 g body wt-1) on exercise performance, tissue glycogen utilization, and lipid availability was determined in male rats. In experiment 1, estradiol or oil was administered 1 h or 1-6 days before a treadmill run to exhaustion. No differences in body weight between oil- and estradiol-administered animals were observed during the 6-day treatment. Animals receiving estradiol for 3-6 days ran significantly longer and completed more work than oil-administered animals. Significant degradation of red and white vastus muscle, myocardial, and liver glycogen was observed in all animals run to exhaustion. In experiment 2, animals were administered estradiol for 5 days and then run for 2 h. The submaximal run for 2 h significantly reduced tissue glycogen content in red and white vastus muscle, heart, and liver of oil-administered animals. The latter effect was attenuated in both vastus muscles, liver, and myocardial tissues in the estradiol-administered animals. Estradiol administration significantly increased plasma fatty acids and lowered plasma lactate during the submaximal run. These data indicate that when body weight remained constant between groups of male rats, estradiol administration for 3-6 days increased exercise performance. Furthermore, estradiol administration for 5 days resulted in greater lipid availability and less tissue glycogen utilization during submaximal running for 2 h.

Dietary macronutrient distribution influences postexercise substrate utilization in women: a cross-sectional evaluation of metabolic flexibility

“…40, 41 Estradiol is thought to play an important role in this sex-based difference, and research in animal models has indicated that estradiol administration increases lipid oxidation while decreasing CHO oxidation. 42, 43 Conversely, other studies have previously found no sex-based RER differences during exercise, 44, 45 and the current study found no correlation between salivary estradiol and RER at any time point. This lack of a relationship could potentially be due to the use of a small, relatively homogeneous sample with relatively low variability in estradiol concentrations.…”

Dietary macronutrient distribution influences postexercise substrate utilization in women: a cross-sectional evaluation of metabolic flexibility

“…40, 41 Estradiol is thought to play an important role in this sex-based difference, and research in animal models has indicated that estradiol administration increases lipid oxidation while decreasing CHO oxidation. 42, 43 Conversely, other studies have previously found no sex-based RER differences during exercise, 44, 45 and the current study found no correlation between salivary estradiol and RER at any time point. This lack of a relationship could potentially be due to the use of a small, relatively homogeneous sample with relatively low variability in estradiol concentrations.…”

17β-Estradiol Supplementation Decreases Glucose Rate of Appearance and Disappearance with No Effect on Glycogen Utilization during Moderate Intensity Exercise in Men

“…The consistency of this finding reaffirms that E2 acts to promote whole-body CHO sparing during exercise by preferentially attenuating hepatic glucose production (Ra) and glucose uptake (Rd). Animal studies support a net sparing of hepatic glycogen use during exercise in response to E2 supplementation (12,15,16). From the current data, we cannot differentiate between an effect of E2 on reducing hepatic gluconeogenesis and/or glycogenolysis; however, a previous study showed that women had a lower glucose recycling rate than men (2), suggesting a lesser flux of CHO precursors through gluconeogenesis.…”

Short-Term 17-β-Estradiol Administration Does Not Affect Metabolism in Young Males

“…Part of the difference between the current study and these studies in rodents may relate to a dosage response. For example in the studies showing glycogen sparing effects after only 5 d of treatment [13] the E 2 concentration was approximately 100 mg kg -1 body weight, which is approximately 35 times higher than the average E 2 concentration to which the subjects in the current study were exposed. Similar effects of E 2 on skeletal and cardiac glycogen metabolism have been observed in rodents following 4 weeks of injections at a lower dose (2.0 mg 100 g -1 body weight) [12].…”

“…Finally this same group found that the E 2 induced an attenuation of skeletal muscle glycogen breakdown that was most apparent in the first 30 min of exercise [20]. Furthermore, E 2 also increased resting plasma free fatty acid and skeletal muscle triacylglycerol concentrations [13].…”

Dietary macronutrient distribution influences postexercise substrate utilization in women: a cross-sectional evaluation of metabolic flexibility

“…40, 41 Estradiol is thought to play an important role in this sex-based difference, and research in animal models has indicated that estradiol administration increases lipid oxidation while decreasing CHO oxidation. 42, 43 Conversely, other studies have previously found no sex-based RER differences during exercise, 44, 45 and the current study found no correlation between salivary estradiol and RER at any time point. This lack of a relationship could potentially be due to the use of a small, relatively homogeneous sample with relatively low variability in estradiol concentrations.…”

17β-Estradiol Supplementation Decreases Glucose Rate of Appearance and Disappearance with No Effect on Glycogen Utilization during Moderate Intensity Exercise in Men

“…The consistency of this finding reaffirms that E2 acts to promote whole-body CHO sparing during exercise by preferentially attenuating hepatic glucose production (Ra) and glucose uptake (Rd). Animal studies support a net sparing of hepatic glycogen use during exercise in response to E2 supplementation (12,15,16). From the current data, we cannot differentiate between an effect of E2 on reducing hepatic gluconeogenesis and/or glycogenolysis; however, a previous study showed that women had a lower glucose recycling rate than men (2), suggesting a lesser flux of CHO precursors through gluconeogenesis.…”

Short-Term 17-β-Estradiol Administration Does Not Affect Metabolism in Young Males

“…Part of the difference between the current study and these studies in rodents may relate to a dosage response. For example in the studies showing glycogen sparing effects after only 5 d of treatment [13] the E 2 concentration was approximately 100 mg kg -1 body weight, which is approximately 35 times higher than the average E 2 concentration to which the subjects in the current study were exposed. Similar effects of E 2 on skeletal and cardiac glycogen metabolism have been observed in rodents following 4 weeks of injections at a lower dose (2.0 mg 100 g -1 body weight) [12].…”

“…Finally this same group found that the E 2 induced an attenuation of skeletal muscle glycogen breakdown that was most apparent in the first 30 min of exercise [20]. Furthermore, E 2 also increased resting plasma free fatty acid and skeletal muscle triacylglycerol concentrations [13].…”

Dietary macronutrient distribution influences postexercise substrate utilization in women: a cross-sectional evaluation of metabolic flexibility

“…40, 41 Estradiol is thought to play an important role in this sex-based difference, and research in animal models has indicated that estradiol administration increases lipid oxidation while decreasing CHO oxidation. 42, 43 Conversely, other studies have previously found no sex-based RER differences during exercise, 44, 45 and the current study found no correlation between salivary estradiol and RER at any time point. This lack of a relationship could potentially be due to the use of a small, relatively homogeneous sample with relatively low variability in estradiol concentrations.…”

17β-Estradiol Supplementation Decreases Glucose Rate of Appearance and Disappearance with No Effect on Glycogen Utilization during Moderate Intensity Exercise in Men

“…The consistency of this finding reaffirms that E2 acts to promote whole-body CHO sparing during exercise by preferentially attenuating hepatic glucose production (Ra) and glucose uptake (Rd). Animal studies support a net sparing of hepatic glycogen use during exercise in response to E2 supplementation (12,15,16). From the current data, we cannot differentiate between an effect of E2 on reducing hepatic gluconeogenesis and/or glycogenolysis; however, a previous study showed that women had a lower glucose recycling rate than men (2), suggesting a lesser flux of CHO precursors through gluconeogenesis.…”

Short-Term 17-β-Estradiol Administration Does Not Affect Metabolism in Young Males

“…Part of the difference between the current study and these studies in rodents may relate to a dosage response. For example in the studies showing glycogen sparing effects after only 5 d of treatment [13] the E 2 concentration was approximately 100 mg kg -1 body weight, which is approximately 35 times higher than the average E 2 concentration to which the subjects in the current study were exposed. Similar effects of E 2 on skeletal and cardiac glycogen metabolism have been observed in rodents following 4 weeks of injections at a lower dose (2.0 mg 100 g -1 body weight) [12].…”

“…Finally this same group found that the E 2 induced an attenuation of skeletal muscle glycogen breakdown that was most apparent in the first 30 min of exercise [20]. Furthermore, E 2 also increased resting plasma free fatty acid and skeletal muscle triacylglycerol concentrations [13].…”