RESUMO
We investigated the effect of a chronic palatable diet rich in simple sugars on memory of different degrees of emotionality in male adult rats, and on hippocampal plasticity markers in different stages of development. On postnatal day (PND) 21, 45 male Wistar rats were divided in two groups, according to their diet: (1-Control) receiving standard lab chow or (2-Palatable Diet) receiving both standard chow plus palatable diet ad libitum. At PND 60, behavioral tests were performed to investigate memory in distinct tasks. Hippocampal plasticity markers were investigated at PND 28 in half of the animals, and after the behavioral tests. Palatable diet consumption induced an impairment in memory, aversive or not, and increased Na+ , K+ -ATPase activity, both at PND 28, and in the adulthood. Synaptophysin, brain-derived neurotrophic factor (BDNF), and protein kinase B (AKT), and phosphorylated AKT were reduced in the hippocampus at PND 28. However, at PND 75, this diet consumption led to increased hippocampal levels of synaptophysin, spinophilin/neurabin-II, and decreased BDNF and neuronal nitric oxide synthase. These results showed a strongly association of simple sugars-rich diet consumption during the development with memory impairments. Plasticity markers are changed, with results that depend on the stage of development evaluated.
RESUMO
We have previously described a theoretical model in humans, called "Similarities in the Inequalities", in which extremely unequal social backgrounds coexist in a complex scenario promoting similar health outcomes in adulthood. Based on the potential applicability of and to further explore the "similarities in the inequalities" phenomenon, this study used a rat model to investigate the effect of different nutritional backgrounds during gestation on the willingness of offspring to engage in physical activity in adulthood. Sprague-Dawley rats were time mated and randomly allocated to one of three dietary groups: Control (Adlib), receiving standard laboratory chow ad libitum; 50% food restricted (FR), receiving 50% of the ad libitum-fed dam's habitual intake; or high-fat diet (HF), receiving a diet containing 23% fat. The diets were provided from day 10 of pregnancy until weaning. Within 24 hours of birth, pups were cross-fostered to other dams, forming the following groups: Adlib_Adlib, FR_Adlib, and HF_Adlib. Maternal chow consumption and weight gain, and offspring birth weight, growth, physical activity (one week of free exercise in running wheels), abdominal adiposity and biochemical data were evaluated. Western blot was performed to assess D2 receptors in the dorsal striatum. The "similarities in the inequalities" effect was observed on birth weight (both FR and HF groups were smaller than the Adlib group at birth) and physical activity (both FR_Adlib and HF_Adlib groups were different from the Adlib_Adlib group, with less active males and more active females). Our findings contribute to the view that health inequalities in fetal life may program the health outcomes manifested in offspring adult life (such as altered physical activity and metabolic parameters), probably through different biological mechanisms.
Assuntos
Peso ao Nascer , Restrição Calórica/efeitos adversos , Dieta Hiperlipídica/efeitos adversos , Fenômenos Fisiológicos da Nutrição Materna , Efeitos Tardios da Exposição Pré-Natal/fisiopatologia , Gordura Abdominal/metabolismo , Animais , Feminino , Desenvolvimento Fetal , Comportamentos Relacionados com a Saúde , Masculino , Modelos Animais , Neostriado/metabolismo , Gravidez , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores de Dopamina D2/metabolismo , Fatores Socioeconômicos , Aumento de PesoRESUMO
During the postnatal period, the nervous system is modified and shaped by experience, in order to adjust it to the particular environment in which the animal will live. This plasticity, one of the most remarkable characteristics of the nervous system, promotes adaptive changes, but it also makes brain more vulnerable to insults. This chapter will focus on the effects of interventions during the postnatal development in animal models of neonatal handling (usually up to 15 min of handling) and maternal separation (usually at least for 3 h). Sex-specific changes and effects of prepubertal stress such as social isolation later on in life were also considered. These interventions during development induce long-lasting traces in the pups' nervous system, which will be reflected in changes in neuroendocrine functions, including the hypothalamus-pituitary-adrenal and hypothalamus-pituitary-gonadal axes; anxiety and cognitive performance; and feeding, sexual, and social behavior. These enduring changes may be adaptive or maladaptive, depending on the environment in which the animal will live. The challenge researchers facing now is to determine how to reverse the deleterious effects that may result from early-life stress exposure.
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In the present study, we investigated whether maternal exposure to a cafeteria diet affects the metabolism and body composition of offspring and whether such an exposure has a cumulative effect during the lifetime of the offspring. Female rats were fed a control (CON) or a cafeteria (CAF) diet from their own weaning to the weaning of their offspring. At 21 d of age, male offspring were divided into four groups by diet during gestation and after weaning (CON-CON, CON-CAF, CAF-CON and CAF-CAF). Blood was collected from dams (after weaning) and pups (at 30 and 120 d of age) by decapitation. CAF dams had significantly greater body weight and adipose tissue weight and higher concentrations of total cholesterol, insulin and leptin than CON dams (Student's t test). The energy intake of CAF rats was higher than that of CON rats regardless of the maternal diet (two-way ANOVA). Litters had similar body weights at weaning and at 30 d of age, but at 120 d, CON-CAF rats were heavier. At both ages, CAF rats had greater adipose tissue weight than CON rats regardless of the maternal diet, and the concentrations of TAG and cholesterol were similar between the two groups, as were blood glucose concentrations at 30 d of age. However, at 120 d of age, CAF rats were hyperglycaemic, hyperinsulinaemic and hyperleptinaemic regardless of the maternal diet. These findings suggest that maternal obesity does not modulate the metabolism of male offspring independently, modifying body weight only when associated with the intake of a cafeteria diet by the offspring.
Assuntos
Tecido Adiposo , Peso Corporal , Dieta/efeitos adversos , Leptina/sangue , Doenças Metabólicas/etiologia , Obesidade/etiologia , Fenômenos Fisiológicos da Nutrição Pré-Natal , Animais , Glicemia/metabolismo , Colesterol/sangue , Dieta/normas , Feminino , Hiperglicemia/sangue , Hiperglicemia/etiologia , Hiperinsulinismo/sangue , Hiperinsulinismo/etiologia , Insulina/sangue , Masculino , Doenças Metabólicas/sangue , Gravidez , Complicações na Gravidez/etiologia , Ratos , Ratos Wistar , Triglicerídeos/sangue , DesmameRESUMO
Pre-puberty is a critical period for the final maturation of the neural circuits that control energy homeostasis, as external stimuli such as exposure to diets and stress may influence the adaptive responses with long-term repercussions. Our aim is to investigate the effects of isolation stress during early life and of chronic access to palatable diets, rich in sugar or fat, on the metabolic profile (glycemia, plasma lipids, leptin and cholinesterase activity) and oxidative stress parameters in the livers of adult male rats. We observed changes mainly in animals that received the high-fat diet (increased body weight and abdominal fat in adults, as well as increased plasma glucose, and cholinesterase activity), and most of these effects were further increased by exposure to stress. High-fat diet also affected the rats' lipid profile (increased cholesterol, LDL-cholesterol and triglycerides); these effects were more marked in stressed animals. Additionally, exposure to stress led to an oxidative imbalance in the liver, by increasing production of reactive species, as well as the activity of antioxidant enzymes (superoxide dismutase and catalase); these effects were accentuated with the high-fat diet (which also caused a severe reduction in glutathione peroxidase activity). Taken together, these results show that the pre-pubertal period constitutes a critical window for stressful interventions during development, leading to alterations in metabolic parameters and increased oxidative stress during adulthood that may be more pronounced in animals that receive a high-fat diet.
Assuntos
Gordura Abdominal/crescimento & desenvolvimento , Glândulas Suprarrenais/crescimento & desenvolvimento , Envelhecimento/metabolismo , Lipídeos/sangue , Fígado/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Isolamento Social , Gordura Abdominal/efeitos dos fármacos , Gordura Abdominal/metabolismo , Envelhecimento/efeitos dos fármacos , Animais , Glicemia/metabolismo , Peso Corporal/efeitos dos fármacos , Catalase/metabolismo , Colinesterases/sangue , Gorduras na Dieta/farmacologia , Sacarose Alimentar/farmacologia , Ingestão de Alimentos/efeitos dos fármacos , Ingestão de Energia/efeitos dos fármacos , Radicais Livres/metabolismo , Glutationa Peroxidase/metabolismo , Leptina/sangue , Fígado/efeitos dos fármacos , Masculino , Tamanho do Órgão , Ratos , Compostos de Sulfidrila/metabolismo , Superóxido Dismutase/metabolismoRESUMO
Chronic stress increases anxiety and encourages intake of palatable foods as "comfort foods". This effect seems to be mediated by altered function of the hypothalamic-pituitary-adrenal axis. In the current study, litters of Wistar rats were subjected to limited access to nesting material (Early-Life Stress group - ELS) or standard care (Control group) from postnatal day 2 to 9. In adult life, anxiety was assessed using the novelty-suppressed feeding test (NSFT), and acute stress responsivity by measurement of plasma corticosterone and ACTH levels. Preference for palatable foods was monitored by a computerized system (BioDAQ, Research Diets(®)) in rats receiving only regular chow or given the choice of regular and palatable diet for 30 days. ELS-augmented adulthood anxiety in the NSFT (increased latency to eat in a new environment; decreased chow intake upon return to the home cage) and increased corticosterone (but not ACTH) secretion in response to stress. Despite being lighter and consuming less rat chow, ELS animals ate more palatable foods during chronic exposure compared with controls. During preference testing, controls receiving long-term access to palatable diet exhibited reduced preference for the diet relative to controls exposed to regular chow only, whereas ELS rats demonstrated no such reduction in preference after prolonged palatable diet exposure. The increased preference for palatable foods showed by ELS animals may result from a habit of using this type of food to ameliorate anxiety.
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Ansiedade/etiologia , Preferências Alimentares/psicologia , Estresse Psicológico/complicações , Gordura Abdominal/anatomia & histologia , Hormônio Adrenocorticotrópico/sangue , Fenômenos Fisiológicos da Nutrição Animal , Animais , Corticosterona/sangue , Dieta , Ingestão de Alimentos/fisiologia , Comportamento Alimentar , Feminino , Sistema Hipotálamo-Hipofisário , Sistema Hipófise-Suprarrenal , Ratos , Ratos Wistar , Restrição FísicaRESUMO
Social isolation during early development is one of the most potent stressors that can cause alterations in the processes of brain maturation, leading to behavioral and neurochemical changes that may persist to adulthood. Exposure to palatable diets during development can also affect neural circuits with long-term consequences. The aims of the present study were to investigate the long-term effects of isolation stress during the pre-pubertal period on the exploratory and anxiety-like behavior, the oxidative stress parameters and the respiratory chain enzymes activities in the hippocampus of adult male rats under chronic palatable diets. The results showed that isolated rats receiving either normal or high-fat diet during the pre-pubertal period presented an anxiolytic-like behavior. The animals exposed to stress and treated with high-carbohydrate diet, rich in disaccharides, on the other hand, presented the opposite pattern of behavior. Stress in the pre-pubertal period also leads to decreased activity of the antioxidant enzymes and the mitochondrial respiratory chain complexes II and IV and decreased total thiol content. These effects were reversed by high-fat diet when it was associated with stress. The effects of a sub-acute pre-pubertal isolation stress on anxiety-like behavior and on hippocampal oxidative imbalance during adulthood appear to be modulated by different types of diets, and probably different mechanisms are involved.
Assuntos
Ansiedade , Comportamento Animal , Dieta , Estresse Oxidativo , Maturidade Sexual , Animais , Transporte de Elétrons , Masculino , Ratos , Isolamento SocialRESUMO
OBJECTIVES: Social isolation during the prepubertal period may have long-term effects on metabolism. The exposure to stressful events is associated with increased palatable food intake, constituting reward-based eating. However, palatable food consumption in early life may lead to metabolic alterations later in life. We investigated whether isolation stress during early life can lead to metabolic alterations in male and female rats with or without exposure to a palatable diet. METHODS: Animals were stressed by isolation during one week after weaning, with or without exposure to a palatable diet. RESULTS: Stress and palatable diet induced increased caloric consumption. In females, there was a potentiation of consumption in animals exposed to stress and palatable diet, reflected by increased weight gain and triacylglycerol levels in juveniles, as well as increased adiponectin levels. Most of the effects had disappeared in the adults. Different effects were observed in males: in juveniles, stress increased unacylated ghrelin levels, and hypothalamic neuropeptide Y (NPY). Subsequently, adult males that were exposed to a palatable diet during prepuberty showed increased body weight and retroperitoneal fat deposition, increased glycemia, and decreased plasma adiponectin and hypothalamic NPY. Exposure to stress during prepuberty led to increased adrenals during adulthood, decreased LDL-cholesterol and increased triacylglycerol levels. CONCLUSION: Isolation stress and consumption of palatable diet changes metabolism in a sex-specific manner. Prepuberty female rats were more prone to stress effects on food consumption, while males showed more long-lasting effects, being more susceptible to a metabolic programming after the consumption of a palatable diet.
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Ingestão de Alimentos , Maturidade Sexual/fisiologia , Isolamento Social , Estresse Psicológico/metabolismo , Adiponectina/sangue , Animais , Glicemia/análise , Feminino , Hipotálamo/química , Insulina/sangue , Masculino , Neuropeptídeo Y/análise , Ratos , Ratos Wistar , Caracteres Sexuais , Aumento de PesoRESUMO
The effects of neonatal handling and the absence of ovarian hormones on the olfactory memory related to a palatable food in adulthood were investigated. Oxidative stress parameters and Na+/K+-ATPase activity in the hippocampus and olfactory bulb of adult pre-puberty ovariectomized female rats handled or not in the neonatal period were also evaluated. Litters were non-handled or handled (10 min/day, days 1-10 after birth). Females from each litter were divided into: OVX (subjected to ovariectomy), sham, and intact. When adults, olfactory memory related to a palatable food (chocolate) was evaluate using the hole-board olfactory task. Additionally, oxidative stress parameters and Na+/K+-ATPase activity were measured in the hippocampus and olfactory bulb. No difference between groups was observed considering olfactory memory evaluation. Neonatal handled rats presented an increase in Na+/K+-ATPase activity in the hippocampus and in the olfactory bulb, compared to non-handled ones. Considering the surgical procedure, there was a decrease in Na+/K+-ATPase and catalase activities in sham and OVX groups, compared to intact animals in the olfactory bulb. We concluded that olfactory memory related to a palatable food in adulthood was not affected by neonatal handling or by pre-puberty surgery, with or without removal of ovaries. The difference observed between groups in catalase and Na+/K+-ATPase activity does not seem to be related to the olfactory memory. Additionally, the increase in Na+/K+-ATPase activity (an enzyme that maintains the neurochemical gradient necessary for neuronal excitability) induced by neonatal handling may be related to neuroplastic changes in the hippocampus and olfactory bulb.
Assuntos
Manobra Psicológica , Hipocampo/metabolismo , Memória/fisiologia , Bulbo Olfatório/metabolismo , Percepção Olfatória/fisiologia , ATPase Trocadora de Sódio-Potássio/metabolismo , Ração Animal , Animais , Catalase/metabolismo , Feminino , Glutationa Peroxidase/metabolismo , Ovariectomia , Estresse Oxidativo/fisiologia , Ratos , Ratos Wistar , Superóxido Dismutase/metabolismo , PaladarRESUMO
Early life events can change biochemical, endocrine and behavioral aspects throughout the life of an animal. Since there is a strong relationship between stress, neonatal handling and feeding behavior, the aim of this study was to investigate the effects of these three factors on behavioral parameters (anxiety and locomotion), oxidative stress in brain structures (prefrontal cortex and hippocampus) and on plasma glucose. Nests of Wistar rats were handled (10 min/day), or not (control groups), on days 1-10 after birth. Males from these groups were divided into 4 subgroups: (1) stressed by isolation in childhood (pre-puberty) and with access to a highly palatable diet (2) stressed by isolation and receiving standard lab chow (3) not isolated and receiving a highly palatable diet and (4) not isolated and receiving standard chow. The animals were kept under these conditions for 7 days. Rats receiving the highly palatable diet consumed more food, more calories, gained more weight and had a higher plasma glucose level, but had a lower caloric efficiency than the standard chow groups. Both handling and palatable diet were able to increase food consumption on the first day of isolation. Isolation stress had an anxiogenic effect in the plus maze, which was counteracted by handling. Palatable diet increased time spent in the central area of the open field apparatus and in the open arms of the elevated plus maze, showing an anxiolytic effect. The use of both these conditions, however, does not appear to bring additional protection against the effects of stress during this particular period of life, i.e., pre-puberty. In the prefrontal cortex, handling reduced thiol content and appears to imbalance the antioxidant enzymes system, which is counteracted by a palatable diet. Hippocampus seems to be more sensitive than the prefrontal cortex to early interventions, especially to the highly palatable diet, and both handling and diet appear to imbalance the antioxidant enzyme system. Thus, measurements of antioxidant enzymes activities indicate that handling may endanger some brain structures and that the palatable diet was able to prevent some handling effects on antioxidant enzymes, depending on the brain structure.