RESUMEN
Breast cancer is one of the common tumors occurring in woman and despite treatment, the prognostic is poor. Genistein, a soy isoflavone, has been reported to have chemopreventive\chemotherapeutic potential in multiple tumor types. Here, we investigated the genistein antiproliferative effect in MCF-7 breast cancer, underlying the molecular mechanisms involved in this effect. MCF-7 cancer and CCD1059sK fibroblast cells were treated with estradiol (10 nM) or genistein (0.01-100 µM) for 24, 48, and 72 h and the cell proliferation was investigated by MTT; membrane cell permeability was evaluated by LDH and PI incorporation; apoptosis was investigated by externalization of phosphatidylserine by FACS; and presence of autophagy was detected by LC3A/B immunostaining. The expression of apoptotic proteins and antioxidant enzymes was evaluated by qPCR. The results demonstrate that genistein (100 µM) for 72 h of treatment selectively reduced MCF-7 cell proliferation independent of estrogen receptor activation, while no cytotoxicity was observed in fibroblast cells. Further experiments showed that genistein induced phosphatidylserine externalization and LC3A/B immunopositivity in MCF-7 cells, indicating apoptosis and autophagy cell death. Genistein increased in three times proapoptotic BAX/Bcl-2 ratio and promoted a parallel downregulation of 20 times of antiapoptotic survivin. In addition, genistein promoted a decrease of 5.5, 9.3, and 3.6 times of MnSOD, CuZnSOD, and TrxR mRNA expression, respectively, while the GPx expression was increased by 6.5 times. These results suggest that the antitumor effect of genistein involved the modulation of antioxidant enzyme and apoptotic signaling expression, which resulted in apoptosis and progression of autophagy.
Asunto(s)
Apoptosis/efectos de los fármacos , Autofagia/efectos de los fármacos , Neoplasias de la Mama/genética , Genisteína/administración & dosificación , Neoplasias de la Mama/enzimología , Neoplasias de la Mama/patología , Proliferación Celular/efectos de los fármacos , Femenino , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Humanos , Células MCF-7 , Estrés Oxidativo/genética , Proteína X Asociada a bcl-2/metabolismoRESUMEN
Stress-induced alterations in feeding behavior are sexually dimorphic and have been related to changes in monoamine levels. Fluoxetine is commonly used as an antidepressant and has also been suggested as an adjunct to other strategies to treat obese individuals. Leptin may interact with stress hormones and with the brain serotonergic system, possibly affecting the feeding behavior of stressed rats. The aim of this study is to evaluate the interaction between chronic fluoxetine treatment and leptin levels in adult female Wistar rats submitted to chronic variable stress. After 30 days of stress, control and stressed groups were subdivided into two groups that received daily injections of vehicle or fluoxetine (8 mg/kg, i.p.). Body weight was evaluated before and after fluoxetine treatment. The animals gained weight with time, signifying that there is a difference in weight gain over time when fluoxetine-treated animals are, or not, subjected to the stress model. Both fluoxetine and stress induced a decrease in sweet food consumption. On the 60th day of fluoxetine treatment, leptin levels were decreased in fluoxetine-treated animals and there was no effect of stress. We conclude that chronic fluoxetine treatment induced a decreased intake of sweet food, as well as a reduction in leptin levels, and that this result could represent a compensatory response to reduced food intake rather than a direct anorectic mechanism. No interaction with chronic stress was observed.
Asunto(s)
Conducta Alimentaria/efectos de los fármacos , Fluoxetina/farmacología , Leptina/sangre , Inhibidores Selectivos de la Recaptación de Serotonina/farmacología , Estrés Psicológico/sangre , Estrés Psicológico/psicología , Animales , Peso Corporal/efectos de los fármacos , Enfermedad Crónica , Ciclo Estral/efectos de los fármacos , Femenino , Fenómenos Fisiológicos de la Nutrición , Ratas , Ratas WistarRESUMEN
Brief periods of handling during the neonatal period have been shown to have profound and long-lasting physiological consequences. Previous studies performed in our laboratory have demonstrated that handling the pups during the neonatal period leads to increased sweet food ingestion in adult life. The objective of this study is to verify if this effect could be explained by the enhanced anxiety levels in these animals. Litters were divided in: (1) intact; (2) handled (10 min in an incubator/day) and (3) handled + tactile stimulation (10 min/day). Procedures were performed on days 1-10 after birth. When adults, rats were tested in the elevated plus maze apparatus, light dark exploration test and open field test. They were also tested for sweet food ingestion, being injected with 2 mg/kg diazepam or vehicle 60 min before the test. Handling and handling + tactile stimulation do not alter performance in the plus maze test, but handled rats presented more crossings in the light/dark exploration test and open field (two-way ANOVA). Females also spent more % time in the open arms in the plus maze and more time in the lit compartment in the light/dark test, presenting more crossings in both tests. Both treated rats (handled and handled + tactile stimulation groups) consumed more sweet food than intact ones (two-way ANOVA). When diazepam was injected prior to the measurement of sweet food ingestion, there was no effect of the drug. We suggest that handling during the neonatal period leads to plastic alterations in the central nervous system of these animals, causing an increased ingestion of palatable food in adult life, and this alteration does not express an anxiety-like behavior.
Asunto(s)
Ansiedad/fisiopatología , Conducta Animal/fisiología , Conducta Alimentaria/fisiología , Manejo Psicológico , Análisis de Varianza , Animales , Animales Recién Nacidos , Ansiolíticos/farmacología , Conducta Animal/efectos de los fármacos , Diazepam/farmacología , Conducta Exploratoria/fisiología , Conducta Alimentaria/efectos de los fármacos , Femenino , Masculino , Aprendizaje por Laberinto/efectos de los fármacos , Aprendizaje por Laberinto/fisiología , Estimulación Física/métodos , Embarazo , Ratas , Ratas Wistar , Factores Sexuales , Factores de TiempoRESUMEN
Stress during the neonatal period leads to a large number of behavioral and biochemical alterations in adult life. The aim of this study is to verify the effects of handling and tactile stimulation during the first 10 days of life on feeding behavior in adult rats. Litters were divided into (1). intact; (2). handled (10 min/day); and (3). handled and tactile stimulated (10 min/day). Procedures were performed on Days 1-10 after birth. When adults, rats were tested for ingestion of sweet and savory snacks. We also measured body weight, ingestion of standard lab chow, and consumption of water and 1% glucose and 1.5% NaCl solutions. Stressed rats (handling and handling+tactile stimulation groups) consumed more sweet (two-way ANOVA, P=.008) or savory snacks (P=.001) than intact ones. This effect was observed in males and females. There were no differences in body weight, ingestion of standard lab chow, water, or in the ingestion of sweetened or salty solutions between groups. The same animals were tested later in life (15 months of age), and the effect was still evident. We suggest that handling during the neonatal period leads to alterations in the CNS of rats, causing an increased ingestion of palatable food in adult life, and this alteration probably persists throughout the whole life.
Asunto(s)
Animales Recién Nacidos/psicología , Apetito/fisiología , Conducta Alimentaria/fisiología , Manejo Psicológico , Estrés Psicológico/fisiopatología , Factores de Edad , Análisis de Varianza , Animales , Animales Recién Nacidos/fisiología , Conducta Alimentaria/psicología , Femenino , Masculino , Embarazo , Ratas , Ratas Wistar , Gusto/fisiología , Tacto/fisiologíaRESUMEN
Exposure to stress induces a cluster of physiological and behavioral changes in an effort to maintain the homeostasis of the organism. Long-term exposure to stress, however, has detrimental effects on several cell functions such as the impairment of antioxidant defenses leading to oxidative damage. Oxidative stress is a central feature of many diseases. The lungs are particularly susceptible to lesions by free radicals and pulmonary antioxidant defenses are extensively distributed and include both enzymatic and non-enzymatic systems. The aim of the present study was to determine lipid peroxidation and total radical-trapping potential (TRAP) changes in lungs of rats submitted to different models of chronic stress. Adult male Wistar rats weighing 180-230 g were submitted to different stressors (variable stress, N = 7) or repeated restraint stress for 15 (N = 10) or 40 days (N = 6) and compared to control groups (N = 10 each). Lipid peroxidation levels were assessed by thiobarbituric acid reactive substances (TBARS), and TRAP was measured by the decrease in luminescence using the 2-2'-azo-bis(2-amidinopropane)-luminol system. Chronic variable stress induced a 51% increase in oxidative stress in lungs (control group: 0.037 +/- 0.002; variable stress: 0.056 +/- 0.007, P < 0.01). No difference in TBARS was observed after chronic restraint stress, but a significant 57% increase in TRAP was presented by the group repeatedly restrained for 15 days (control group: 2.48 +/- 0.42; stressed: 3.65 +/- 0.16, P < 0.05). We conclude that different stressors induce different effects on the oxidative status of the organism.
Asunto(s)
Peroxidación de Lípido , Pulmón/metabolismo , Estrés Oxidativo , Estrés Fisiológico/metabolismo , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismo , Animales , Modelos Animales de Enfermedad , Radicales Libres/metabolismo , Masculino , Ratas , Ratas Wistar , Restricción FísicaRESUMEN
Exposure to stress induces a cluster of physiological and behavioral changes in an effort to maintain the homeostasis of the organism. Long-term exposure to stress, however, has detrimental effects on several cell functions such as the impairment of antioxidant defenses leading to oxidative damage. Oxidative stress is a central feature of many diseases. The lungs are particularly susceptible to lesions by free radicals and pulmonary antioxidant defenses are extensively distributed and include both enzymatic and non-enzymatic systems. The aim of the present study was to determine lipid peroxidation and total radical-trapping potential (TRAP) changes in lungs of rats submitted to different models of chronic stress. Adult male Wistar rats weighing 180-230 g were submitted to different stressors (variable stress, N = 7) or repeated restraint stress for 15 (N = 10) or 40 days (N = 6) and compared to control groups (N = 10 each). Lipid peroxidation levels were assessed by thiobarbituric acid reactive substances (TBARS), and TRAP was measured by the decrease in luminescence using the 2-2'-azo-bis(2-amidinopropane)-luminol system. Chronic variable stress induced a 51 percent increase in oxidative stress in lungs (control group: 0.037 ± 0.002; variable stress: 0.056 ± 0.007, P < 0.01). No difference in TBARS was observed after chronic restraint stress, but a significant 57 percent increase in TRAP was presented by the group repeatedly restrained for 15 days (control group: 2.48 ± 0.42; stressed: 3.65 ± 0.16, P < 0.05). We conclude that different stressors induce different effects on the oxidative status of the organism.
Asunto(s)
Animales , Masculino , Ratas , Peroxidación de Lípido , Pulmón , Estrés Oxidativo , Estrés Fisiológico , Sustancias Reactivas al Ácido Tiobarbitúrico , Modelos Animales de Enfermedad , Radicales Libres , Ratas Wistar , Restricción FísicaRESUMEN
Exposure to stress may cause either an increase or a decrease in food intake. Behavioral and physiological responses to stress, including alterations in feeding behavior, are sexually dimorphic. This study aimed to evaluate the interaction between estradiol levels and chronic variate stress on the intake of sweet food and on serum levels of leptin, a hormone secreted by the adipose cells with a role in the regulation of body weight. Adult female Wistar rats were used. After ovariectomy, the animals received estradiol replacement (or oil) subcutaneously. Rats were then divided in controls and stressed (submitted to 30 days of variate stress). Consumption of sweet food and of serum leptin was measured. Although animals receiving estradiol replacement presented smaller weight gain, they showed an increased consumption of sweet food. Chronic variate stress decreased sweet food intake at 30, but not at 20, days of treatment. Estradiol replacement in the stressed group prevented both the reduction observed in sweet food intake and the increase in leptin levels. These results suggest that there is an interaction between chronic stress and estradiol replacement in feeding behavior concerning sweet food consumption, and this interaction may be related to altered leptin levels.
Asunto(s)
Estradiol/farmacología , Terapia de Reemplazo de Estrógeno , Conducta Alimentaria/efectos de los fármacos , Leptina/sangre , Estrés Psicológico/sangre , Estrés Psicológico/psicología , Animales , Peso Corporal/efectos de los fármacos , Peso Corporal/fisiología , Enfermedad Crónica , Femenino , Preferencias Alimentarias/efectos de los fármacos , Preferencias Alimentarias/psicología , Ovariectomía , Ratas , Ratas Wistar , Aumento de Peso/efectos de los fármacos , Aumento de Peso/fisiologíaRESUMEN
Chronic variate stress was seen to decrease the ingestion of sweet food when compared to control rats. Brain monoamines are known to be involved in the control of food intake, serotonin appears to be involved in the mechanisms of satiety, and dopamine in mediating appetite or approach behaviors triggered by incentive stimuli associated with rewards. The effect of chronic variate stress on cerebral levels of monoamines was also studied in rats. Increased levels of DOPAC were observed in the frontal cortex and in the hippocampus and an increased 5-HIAA/5-HT ratio was also observed in this latter structure. In the hypothalamus, levels of HVA and DOPAC were decreased, as well as the DOPAC/DA ratio, while no difference was found in amygdala. During the treatment, there were no differences in the consumption of water and regular food between stressed and control animals. An increase in the adrenal weight was observed at the end of the treatment. The results suggest that emotional changes, such as exposure to stress situations can influence feeding behavior, chronic variate stress causes decreased ingestion of sweet food and decreased dopaminergic neurotransmission in hypothalamus. Increased dopamine metabolite levels in the cortex and hippocampus were also observed and some of these modifications may be related to alterations in feeding behavior.
Asunto(s)
Monoaminas Biogénicas/metabolismo , Química Encefálica/fisiología , Conducta Alimentaria/fisiología , Estrés Psicológico/metabolismo , Animales , Peso Corporal/fisiología , Enfermedad Crónica , Dopamina/metabolismo , Ingestión de Líquidos , Privación de Alimentos/fisiología , Ácido Hidroxiindolacético/metabolismo , Masculino , Estimulación Luminosa , Ratas , Ratas Wistar , Restricción Física , Serotonina/metabolismo , Aislamiento Social , Natación/psicología , Privación de Agua/fisiologíaRESUMEN
Monoaminergic systems are important modulators of the responses to stress. Stress may influence feeding behavior, and the involvement of monoamines in the control of food intake is well recognized. We investigated the effects induced by chronic-restraint stress, 1 h a day, for 40 days, on eating behavior and on monoamines in distinct brain structures. Increased consumption of sweet pellets, and not of peanuts, was observed. Dopamine (DA), serotonin (5-HT), and their metabolites were measured by HPLC-EC. After chronic restraint, the results observed were decreased 5-HT in hippocampus, with increased 5-HIAA/5-HT; decreased 5-HIAA levels in cortex; reduction in DA in hippocampus, and increased levels in amygdala and hypothalamus; HVA increased in cortex, as well as HVA/DA ratio, while DOPAC/DA decreased. HVA decreased in hypothalamus, as well as HVA/DA, and DOPAC/DA and HVA/DA decreased in the amygdala. These results suggest that restraint stress differentially affects the activity of central dopaminergic and serotonergic neurons, and this may be related to the effects observed in eating behavior.
Asunto(s)
Monoaminas Biogénicas/metabolismo , Encéfalo/metabolismo , Conducta Alimentaria , Inmovilización , Estrés Fisiológico/metabolismo , Animales , Cromatografía Líquida de Alta Presión , Electroquímica , Masculino , Ratas , Ratas WistarRESUMEN
It has been suggested that glucocorticoids released during stress might impair neuronal function by decreasing glucose uptake by hippocampal neurons. Previous work has demonstrated that glucose uptake is reduced in hippocampal and cerebral cortex slices 24 h after exposure to acute stress, while no effect was observed after repeated stress. Here, we report the effect of acute and repeated restraint stress on glucose oxidation to CO2 in hippocampal and cerebral cortex slices and on plasma glucose and corticosterone levels. Male adult Wistar rats were exposed to restraint 1 h/day for 50 days in the chronic model. In the acute model there was a single exposure. Immediately or 24 h after stress, the animals were sacrificed and the hippocampus and cerebral cortex were dissected, sliced, and incubated with Krebs buffer, pH 7.4, containing 5 mM glucose and 0.2 microCi D-[U-14C] glucose. CO2 production from glucose was estimated. Trunk blood was also collected, and both corticosterone and glucose were measured. The results showed that corticosterone levels after exposure to acute restraint were increased, but the increase was smaller when the animals were submitted to repeated stress. Blood glucose levels increased after both acute and repeated stress. However, glucose utilization, measured as CO2 production in hippocampal and cerebral cortex slices, was the same in stressed and control groups under conditions of both acute and chronic stress. We conclude that, although stress may induce a decrease in glucose uptake, this effect is not sufficient to affect the energy metabolism of these cells.
Asunto(s)
Dióxido de Carbono/metabolismo , Corteza Cerebral/metabolismo , Glucosa/metabolismo , Hipocampo/metabolismo , Estrés Fisiológico/metabolismo , Enfermedad Aguda , Animales , Glucemia/análisis , Enfermedad Crónica , Corticosterona/sangre , Masculino , Oxidación-Reducción , Ratas , Ratas WistarRESUMEN
It has been suggested that glucocorticoids released during stress might impair neuronal function by decreasing glucose uptake by hippocampal neurons. Previous work has demonstrated that glucose uptake is reduced in hippocampal and cerebral cortex slices 24 h after exposure to acute stress, while no effect was observed after repeated stress. Here, we report the effect of acute and repeated restraint stress on glucose oxidation to CO2 in hippocampal and cerebral cortex slices and on plasma glucose and corticosterone levels. Male adult Wistar rats were exposed to restraint 1 h/day for 50 days in the chronic model. In the acute model there was a single exposure. Immediately or 24 h after stress, the animals were sacrificed and the hippocampus and cerebral cortex were dissected, sliced, and incubated with Krebs buffer, pH 7.4, containing 5 mM glucose and 0.2 æCi D-[U-14C] glucose. CO2 production from glucose was estimated. Trunk blood was also collected, and both corticosterone and glucose were measured. The results showed that corticosterone levels after exposure to acute restraint were increased, but the increase was smaller when the animals were submitted to repeated stress. Blood glucose levels increased after both acute and repeated stress. However, glucose utilization, measured as CO2 production in hippocampal and cerebral cortex slices, was the same in stressed and control groups under conditions of both acute and chronic stress. We conclude that, although stress may induce a decrease in glucose uptake, this effect is not sufficient to affect the energy metabolism of these cells
Asunto(s)
Animales , Masculino , Ratas , Dióxido de Carbono/metabolismo , Corteza Cerebral/metabolismo , Glucosa/metabolismo , Hipocampo/metabolismo , Estrés Fisiológico/metabolismo , Enfermedad Aguda , Glucemia/análisis , Enfermedad Crónica , Corticosterona/sangre , Oxidación-Reducción , Ratas WistarRESUMEN
It has been suggested that oxidative stress is involved in aging and neuropathologic disorders. In addition, chronic stress and high corticosterone levels are suggested to induce neuronal death. The aim of this study is to verify the effect of chronic variate stress on lipoperoxidation and on the total radical-trapping potential (TRAP) in hippocampus, hypothalamus and cerebral cortex. Adult male Wistar rats were submitted to different stressors during 40 days. Lipid peroxide levels were assessed by the thiobarbituric acid reactive species (TBARS) reaction, and TRAP was measured by the decrease in luminescence using the 2-2'-azo-bis(2-amidinopropane)-luminol system. The results showed that in cerebral cortex homogenates chronic stress induces an increase in oxidative stress. In hypothalamus a decreased lipoperoxidation was observed, however TRAP showed no difference. In hippocampus no difference was observed. We concluded that prolonged stress induces oxidative stress which varies selectively with the brain region.
Asunto(s)
Encéfalo/metabolismo , Estrés Oxidativo , Estrés Fisiológico/metabolismo , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismo , Animales , Depuradores de Radicales Libres , Peroxidación de Lípido , Masculino , Ratas , Ratas WistarRESUMEN
The present study investigated the effect of repeated stress applied to female rats on memory evaluated by three behavioral tasks: two-way shuttle avoidance, inhibitory avoidance and habituation to an open field. Repeated stress had different effects on rat behavior when different tasks were considered. In the two-way active avoidance test the stressed animals presented memory of the task, but their memory scores were impaired when compared to all other groups. In the habituation to the open field, only the control group showed a significant difference in the number of rearings between training and testing sessions, which is interpreted as an adequate memory of the task. In the handled and chronically stressed animals, on the other hand, no memory was observed, suggesting that even a very mild repeated stress would be enough to alter habituation to this task. The performance in the inhibitory avoidance task presented no significant differences between groups. The findings suggest that repeated restraint stress might induce cognitive impairments that are dependent on the task and on stress intensity.
Asunto(s)
Reacción de Prevención , Memoria , Estrés Fisiológico , Análisis de Varianza , Animales , Conducta Animal , Femenino , Ratas , Ratas Wistar , Restricción Física , Estrés Fisiológico/psicologíaRESUMEN
The present study investigated the effect of repeated stress applied to female rats on memory evaluated by three behavioral tasks: two-way shuttle avoidance, inhibitory avoidance and habituation to an open field. Repeated stress had different effects on rat behavior when different tasks were considered. In the two-way active avoidance test the stressed animals presented memory of the task, but their memory scores were impaired when compared to all other groups. In the habituation to the open field, only the control group showed a significant difference in the number of rearings between training and testing sessions, which is interpreted as an adequate memory of the task. In the handled and chronically stressed animals, on the other hand, no memory was observed, suggesting that even a very mild repeated stress would be enough to alter habituation to this task. The performance in the inhibitory avoidance task presented no significant differences between groups. The findings suggest that repeated restraint stress might induce cognitive impairments that are dependent on the task and on stress intensity
Asunto(s)
Animales , Ratas , Femenino , Reacción de Prevención , Memoria , Estrés Fisiológico , Análisis de Varianza , Conducta Animal , Ratas Wistar , Restricción Física , Estrés Fisiológico/psicologíaRESUMEN
The effects of acute and repeated restraint stress on nociception, as measured by the tail-flick latency, were studied in adult male and female rats. After the exposure to a single restraint session, both male and female rats presented an increased latency in the tail-flick test. On the other hand, chronically stressed females presented a performance similar to the control group, whereas chronically stressed male rats responded to restraint with a decrease in the tail-flick latency. This response could be determined by the chronic treatment itself or by the restraint done just before the measurement. Thus, the effect of chronic stress upon basal tail-flick latency was evaluated. In male rats, this latency was significantly decreased in the stressed animals compared with the control group. In female rats, no difference between those groups was observed. Therefore, the results suggest that: (a) acute restraint stress induces an analgesic response in both male and female rats, and (b) there is a gender-specific nociceptive response induced by repeated restraint stress with a hyperalgesic effect in response to stress only in males.
Asunto(s)
Nociceptores/fisiología , Estrés Psicológico/psicología , Animales , Femenino , Masculino , Dimensión del Dolor , Ratas , Ratas Wistar , Recurrencia , Restricción Física , Caracteres Sexuales , Estrés Psicológico/fisiopatologíaRESUMEN
Epinephrine released or administered soon after a given training task modulates memory processes. Since epinephrine does not readily cross the blood-brain barrier, studies have suggested that some of the central effects of epinephrine might be mediated by peripheral release of glucose. These experiments examined the involvement of blood glucose levels in the posttraining effects of peripherally administered epinephrine. The effects of the administration of epinephrine (25 and 625 microg/kg) [corrected] on memory of an inhibitory avoidance task were evaluated in fed and fasted rats (depleted glycogen stores in liver). Blood glucose levels after the task in each group were also measured. Female Wistar rats were divided in two groups. Fed and 48-h-fasted animals were submitted to the inhibitory avoidance task and received i.p. epinephrine or saline immediately after training. The test session was carried out 48 h after training. Epinephrine (25 or 625 microg/kg) [corrected] caused an increased glycemia in fed rats, but no effect was observed in fasted animals. Administration of epinephrine 25 microg/kg [corrected] induced a facilitation of memory, while epinephrine 625 microg/kg [corrected] impaired retention (either in fasted or in fed animals). There was no relation between increased glycemia induced by epinephrine and its effects on memory, since this drug presented its classical effects independently of the previous state of the animal (fed or fasted). The results of the present study suggest that the effects of systemic released or administered epinephrine on memory processes are not dependent on hepatic glucose release.
Asunto(s)
Reacción de Prevención/efectos de los fármacos , Glucemia/metabolismo , Epinefrina/farmacología , Hígado/efectos de los fármacos , Recuerdo Mental/efectos de los fármacos , Retención en Psicología/efectos de los fármacos , Animales , Relación Dosis-Respuesta a Droga , Femenino , Inhibición Psicológica , Glucógeno Hepático/metabolismo , Ratas , Ratas Wistar , Tiempo de Reacción/efectos de los fármacosRESUMEN
The expression of appetite reflects the complex functioning of a psychobiological system organized in different levels closely related to each other, in which emotional changes can influence feeding behavior. Benzodiazepines are widely used as anxiolytics and can change behaviors caused by stress. The aim of the present study was to verify the feeding behavior of rats, submitted or not to fasting, after acute and chronic restraint stress. We also evaluated the response to the ingestion of sweet food of chronically restrained animals after the administration of diazepam. Male adult Wistar rats were exposed to restraint 1 h/day for 50 days in the chronic model. In the acute model, there was a single exposure. Four hours after the stress, the animals were placed in a lightened area in the presence of 10 pellets of sweet food (Froot Loops). The number of ingested Froot Loops was measured during a period of 3 min in the presence or absence of fasting. The groups acutely stressed showed ingestion similar to that of the control group, whether they had been fasted or not. The chronically stressed animals showed increased ingestion of sweet food. Diazepam given 60 min before the test session of the stressed rats reduced the ingestion of these animals to control levels. Thus, the chronic stress increases appetite for sweet food, independently of hunger, and diazepam is able to reverse this behavior.