Effect of Food Restriction and Intense Physical Training on Estrous Cyclicity and Plasma Leptin Concentrations in Rats

Abstract

SummaryIntense physical training and dietary energy restriction have been associated with consequences such as nutritional amenorrhea. We investigated the effects of intense physical training, food restriction or the combination of both strategies on estrous cyclicity in female rats, and the relationship between leptin ad these effects. Twenty-seven female Wistar rats were distributed into four groups: SF: sedentary, fed ad libitum; SR: sedentary subjected to 50% food restriction (based on the food intake of their fed counterparts); TF: trained (physical training on a motor treadmill with a gradual increase in speed and time), fed ad libitum; TR: trained with 50% food restriction. We analysed estrous cyclicity, plasma leptin and estradiol as well as chemical composition of the carcass, body weight variation, and weight of ovaries and perirenal adipose tissue. Data demonstrate that physical training alone was not responsible for significant modifications in either carcass chemical composition or reproductive function. Food restriction reduced leptin levels in all animals and interrupted the estrous cyclicity in some animals, but only the combination of food restriction and physical training was capable of interrupting the estrous cyclicity in all animals. Leptin was not directly related to estrous cyclicity. From our findings, it may be concluded that there is an additive or synergistic effect of energy intake restriction and energy expenditure by intense physical training on estrous cyclicity. Leptin appears to be one among others factors related to estrous cycle, but it probably acts indirectly. Key Words energy intake, body composition, estrous cycle, leptin, physical exercise Some female athletes are constantly under pressure to achieve and/or to maintain low body weight, leading to potentially harmful patterns of restricted dieting and over exercising. Some of the health consequences of long-term energy restriction include poor nutritional status and risk of exercise-induced amenorrhea ( 1 , 2 ). In humans, this condition is characterized by the absence of menstruation for 90 d or more.Based on epidemiological data, Frisch ( 3 ) reported that, in women and girls, body fat content and ovulatory cyclicity were positively associated. However, one or more main signals that centrally indicates the availability of energy is still unknown ( 4 ). Since physical activity may reduce leptin mRNA expression ( 5 , 6 ) and athletes that train intensively, under restricted calorie intake, present a higher percentage of amenorrhea than sedentary women ( 7 ), it may be speculated that leptin is involved in the transduction of the energy availability signals.Studies on the effects of exercise, reproductive function and leptin response have been hindered by the inability to disassociate the effects of exercise itself from other confusing factors. These factors could be related to energy intake below the requirements or different hormones involved ( 8 , 9 ). It is not clear whether the reproductive functions are interrupted due...

Stress Hormone and Reproductive System in Response to Honey Supplementation Combined with Different Jumping Exercise Intensities in Female Rats

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Establishment of a chronic activity-based anorexia rat model

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Physical activity: benefit or weakness in metabolic adaptations in a mouse model of chronic food restriction?

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