Abstract

The effect of both physiological and pharmacological doses of estradiol on exercise performance and tissue glycogen utilization was determined in oophorectomized estradiol-replaced (ER) rats. Doses of b-estradiol 3-benzoate were injected 5 days/wk for 4 wk. Controls were sham injected (SI). After treatment, the animals were run to exhaustion on a motorized treadmill. ER animals receiving the 0.02-micro g dose ran significantly longer and completed more total work than the SI group. ER animals receiving doses of >= 0.04 micro g ran longer and performed more work than the 0.02-micro-g group. At exhaustion, myocardial glycogen content was significantly decreased in animals that were ER with <= 0.1 micro g. whereas those replaced with doses > 0.1 micro g utilized significantly less glycogen. With the 10-micro-g dose no significant decrease in heart glycogen content was observed at exhaustion. A submaximal 2-h run significantly reduced glycogen content in heart, red and white portions of the vastus lateralis, and the livers of SI animals. The latter effect was attenuated in skeletal muscle and liver, and there was no effect in the hearts of the ER animals receiving 2 micro-g. These data indicated that estradiol replacement in oophorectomized rats influenced myocardial glycogen utilization during exhaustive exercise and spared tissue glycogen during submaximal exercise. These glycogen sparing effects may have contributed to the significant improvements in exercise performance observed in this study. Verf.-Referat