Investigação das alterações do consumo de alimento palatável induzidas por trauma precoce em ratas fêmeas

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

2012

RESUMO

Introduction: Chronic stress in adulthood increases anxiety and prones the individuals to use palatable foods as ¿comfort foods¿, which seems to be mediated by an altered functioning of the hypothalamus-pituitary-adrenal axis (HPA). We aimed at verifying if early life stress also affects anxiety, feeding behavior and stress responses in adult female rats. Methods: By the second day of life litters of Wistar rats were subjected to reduced nesting material (Early¿Life Stress) or standard care (Controls). In adult life, anxiety was accessed using the novelty suppressed feeding test (NSFT), and the neuroendocrine stress response to 20 minutes restraint stress was verified by measuring plasma corticosterone and ACTH levels at baseline and immediately, 20, 40, and 70 min. following the stress exposure. In a different subset of animals, the basal consumption of regular diet as well as the preference for palatable food (rich in fat (34%) and sugar (20%)) was measured in a continuous monitoring computerized system of food consumption (BioDAQ, Research Diets®) in rats receiving only regular chow or exposed to both regular and hyperpalatable diets continuously for 30 days. Body weight gain was measured weekly. At the end of the treatment, T3 levels and the abdominal fat content were measured. Results: Intervention dams showed decreased variability and quality of maternal care compared to control dams. ELS increased adulthood anxiety in the NSFT (latency to eat the sweet pellet in a new environment p=0.005, decreased chow consumption upon the return to the homecage p=0.045), as well as increased corticosterone levels in response to acute restraint stress (p=0.02). No differences were seen in ACTH levels in response to stress. The regular diet intake was different among the groups only during the nocturnal phase of the light cycle, being lower in the intervention group (p=0,047). After being exposed chronically to a palatable diet, the intervention group prefered this type of food when having the option to choose (hyperpalatable food + regular diet) (p=0,008) decreasing the consumption of the regular diet. The body weight gain during the first 72h (p=0,417) and over the 4 weeks of exposure to the palatable diet (0,474) was not different between the groups, as well as no difference was seen on the percentage of abdominal fat (p=0,166). On the preference test with all the groups, while the control group chronically exposed to the hyperpalatable diet showed a diminished preference for the palatable food compared to the control group exposed only to the regular diet, the rats exposed to early life stress did not demonstrate this reduction in preference after the chronic exposure (p<0.001). T3 hormone levels correlated negatively with the licking and grooming (LG) scores in the ELS group (p=0,010). This correlation disappears when is given the oportunity of choice between two diets (p=0,679). Conclusion: Alterations in anxiety and feeding behaviors seen in early stressed animals in this model seem to be related to changes in the neuroendocrine HPA response to acute stress. The consumption of palatable food possibly is used by ELS females rats to inhibit the anxiety symptoms.

ASSUNTO(S)

ansiedade anxiety estresse fisiológico physiological stress comportamento alimentar feeding behavior modelos animais consumo de alimentos

ACESSO AO ARTIGO

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