Moderate physical exercise attenuates the alterations of feeding behaviour induced by social stress in female rats

Abstract

Epidemiological studies have demonstrated that stress-related disorders, such as the increase on the caloric intake, are twice as common in women as in men, but surprisingly, very few studies have been tested this subject on female experimental animals. Additionally, it has been proposed that regular physical exercise can improve the deleterious effects of stress. Therefore, the present longitudinal study, performed in female rats, aimed to test the influence of chronic stress (ST) imposed by social isolation on the animals' caloric intake and to assess the effect of regular physical exercise of low intensity on this behaviour. In 4 groups of Wistars rats (control sedentary, n = 6; control exercised, n = 6; ST sedentary, n = 6; ST exercised, n = 6), body weight, food intake, abdominal fat weight, adrenal weight, corticosterone metabolites in faeces and plasma insulin levels were measured during the experimental protocol and/or at its end. The results showed that social isolation was not able to modify the amount of abdominal fat and the body weight; however, it promoted significant increases in the corticosterone metabolites and in the amount of caloric intake, which were attenuated in exercised rats. Additionally, exercised groups presented lower levels of fasting insulin than sedentary groups. Therefore, the present study demonstrated that regular physical exercise of low intensity attenuates the corticosterone metabolites and overeating behaviour triggered by social stress.

Does High Fat Diet have the Stress-Like Effect on Animals?

“…In our previous study, we demonstrated that isolated females rats increase their intake of fat and that was associated to increase in corticosterone [3], such as in others studies [7,8,16]. In this study, therefore, we test the hypothesis that the increase in corticosterone may be due the increase in high fat food intake per se and not only due the methodology used to induce social stress and verify if high fat food and stress affect mitochondrial homeostasis.…”

“…The fecal samples were collected three times: at beginning of experiment, after two and six weeks. The collection and the treatment was performed as described previously [3].…”

“…This effect leads to increased levels of glucocorticoids, as cortisol and corticosterone [1][2][3]. These hormonal changes can trigger the reward-seeking behavior and increase the motivation for natural recompenses such as highcalorie and palatable foods intake.…”

Avaliação comportamental de ratos treinados em natação forçada

“…O exercício físico tem sido testado para aliviar diversos tipos de estresse experimentalmente induzidos, como isolamento social [5,30], ruídos [35], imobilização, frio [31], privação de alimentos e água [14], dentre outros. Há indícios de que o tipo e a intensidade do exercício, bem como o modelo animal utilizado, podem influenciar nas respostas hormonais e comportamentais [36].…”

“…Em estudo com ratos, o exercício físico de baixa intensidade mostrou-se como um atenuador de alterações tanto de insulina e metabólitos da corticosterona, quanto do comportamento alimentar promovido pelo estresse social induzido pelo isolamento, com provável ação sobre o eixo hipotalâmico-pituitário-adrenal [5]. Observou-se que o exercício retarda o desenvolvimento de neurite autoimune em ratos [6].…”