RESUMO
Emotional changes can influence feeding behavior. Previous studies have shown that chronically stressed animals present increased ingestion of sweet food, an effect reversed by a single dose of diazepam administered before testing the animals. The aim of the present study was to evaluate the response of animals chronically treated with midazolam and/or submitted to repeated restraint stress upon the ingestion of sweet food. Male adult Wistar rats were divided into two groups: controls and exposed to restraint 1 h/day, 5 days/week for 40 days. Both groups were subdivided into two other groups treated or not with midazolam (0.06 mg/ml in their drinking water during the 40-day treatment). The animals were placed in a lighted area in the presence of 10 pellets of sweet food (Froot loops(r)). The number of ingested pellets was measured during a period of 3 min, in the presence or absence of fasting. The group chronically treated with midazolam alone presented increased ingestion when compared to control animals (control group: 2.0 +/- 0.44 pellets and midazolam group: 3.60 +/- 0.57 pellets). The group submitted to restraint stress presented an increased ingestion compared to controls (control group: 2.0 +/- 0.44 pellets and stressed group: 4.18 +/- 0.58 pellets). Chronically administered midazolam reduced the ingestion in stressed animals (stressed/water group: 4.18 +/- 0.58 pellets; stressed/midazolam group: 3.2 +/- 0.49 pellets). Thus, repeated stress increases appetite for sweet food independently of hunger and chronic administration of midazolam can decrease this behavioral effect
Assuntos
Animais , Ratos , Masculino , Ansiolíticos/farmacologia , Sacarose Alimentar , Comportamento Alimentar/efeitos dos fármacos , Midazolam/farmacologia , Estresse Psicológico , Análise de Variância , Peso Corporal , Estudos de Casos e Controles , Ratos Wistar , Restrição FísicaRESUMO
Emotional changes can influence feeding behavior. Previous studies have shown that chronically stressed animals present increased ingestion of sweet food, an effect reversed by a single dose of diazepam administered before testing the animals. The aim of the present study was to evaluate the response of animals chronically treated with midazolam and/or submitted to repeated restraint stress upon the ingestion of sweet food. Male adult Wistar rats were divided into two groups: controls and exposed to restraint 1 h/day, 5 days/week for 40 days. Both groups were subdivided into two other groups treated or not with midazolam (0.06 mg/ml in their drinking water during the 40-day treatment). The animals were placed in a lighted area in the presence of 10 pellets of sweet food (Froot loops). The number of ingested pellets was measured during a period of 3 min, in the presence or absence of fasting. The group chronically treated with midazolam alone presented increased ingestion when compared to control animals (control group: 2.0 +/- 0.44 pellets and midazolam group: 3.60 +/- 0.57 pellets). The group submitted to restraint stress presented an increased ingestion compared to controls (control group: 2.0 +/- 0.44 pellets and stressed group: 4.18 +/- 0.58 pellets). Chronically administered midazolam reduced the ingestion in stressed animals (stressed/water group: 4.18 +/- 0.58 pellets; stressed/midazolam group: 3.2 +/- 0.49 pellets). Thus, repeated stress increases appetite for sweet food independently of hunger and chronic administration of midazolam can decrease this behavioral effect.
Assuntos
Ansiolíticos/farmacologia , Sacarose Alimentar , Comportamento Alimentar/efeitos dos fármacos , Midazolam/farmacologia , Estresse Psicológico , Análise de Variância , Animais , Peso Corporal , Masculino , Ratos , Ratos Wistar , Restrição FísicaRESUMO
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.
Assuntos
Comportamento Alimentar/fisiologia , Estresse Fisiológico/fisiopatologia , Animais , Ansiolíticos/farmacologia , Apetite/efeitos dos fármacos , Apetite/fisiologia , Peso Corporal , Diazepam/farmacologia , Jejum , Comportamento Alimentar/efeitos dos fármacos , Masculino , Ratos , Ratos Wistar , Restrição Física , Edulcorantes/farmacologia , Fatores de TempoRESUMO
Rats were trained and tested in habituation to a novel environment and step-down inhibitory avoidance. Immediately after training in each task the animals received intra-amygdala, intraseptal, or intrahippocampal micro-injections of agonists and antagonists of various neurotransmitter receptors. In the habitation task, intrahippocampal, but not intra-amygdala or intraseptal administration of the NMDA receptor antagonist aminophosphornopentanoic acid (AP5, 5.0 micrograms) or of the muscarinic receptor antagonist, scopolamine (2.0 micrograms) caused amnesia and the indirect antagonist of GABA-A receptors, picrotoxin (0.08 microgram), caused retrograde facilitation. Intrahippocampal administration of the respective agonists, glutamate, oxotremorine, and muscimol, had effects of their own opposite to those of the blockers, and norepinephrine (0.3 microgram) caused memory facilitation. In the avoidance task, results obtained with drug infusions given into the three structures were very similar: in all cases, AP5, scopolamine, and muscimol were amnestic, and glutamate, oxotremorine, norepinephrine, and picrotoxin caused memory facilitation. In addition, also in the three structures, picrotoxin counteracted the amnestic effect of AP5 and/or scopolamine and the beta-adrenoceptor blocker, timolol (0.3 microgram), while ineffective on its own, attenuated all the effects of picrotoxin. The results suggest that similar synaptic mechanisms in the amygdala, medial septum, and hippocampus are involved in memory consolidation: NMDA, muscarinic, and beta-noradrenergic receptors stimulate and GABA-A receptors inhibit this process, and beta-noradrenergic receptors modulate the GABAergic synapses. In the avoidance task these mechanisms operate in the three structures: in habituation only those in the hippocampus are operative. Possibly in each structure these mechanisms regulate, if not actually consolidate, a different aspect, component, or form of memory.
Assuntos
Tonsila do Cerebelo/fisiologia , Hipocampo/fisiologia , Memória/fisiologia , Neurotransmissores , Tonsila do Cerebelo/efeitos dos fármacos , Animais , Aprendizagem da Esquiva , Comportamento Animal , Comportamento Exploratório , Habituação Psicofisiológica , Hipocampo/efeitos dos fármacos , Masculino , Muscimol , Próteses e Implantes , Ratos , Ratos Endogâmicos , Receptores de Neurotransmissores , Projetos de Pesquisa , Retenção Psicológica , Ácido gama-AminobutíricoRESUMO
1. The immediate post-training microinjection of the N-methyl-D-aspartate receptor antagonist amino-5-phosphonopentanoic acid (5 micrograms) or of scopolamine, the cholinergic muscarinic antagonist (2 micrograms), into the dorsal hippocampus of rats caused retrograde amnesia for habituation to a novel environment, as measured by the number of rearings and crossings performed in a test session. In contrast, picrotoxin (0.08 microgram), the indirect GABA-A antagonist, caused retrograde memory facilitation. 2. Receptor agonists administered into the hippocampus had effects opposite to those of the respective antagonists: glutamate (5 micrograms) and oxotremorine (2 micrograms) enhanced memory and muscimol (0.03 microgram) was amnestic. 3. Aminophosphonopentanoic acid, scopolamine and picrotoxin had no effect when injected into the amygdala or medial septum. Our result contrasted with the recent report of an inhibitory avoidance task in which these drugs, at the doses used here, were effective when injected post-training into any of the three structures. 4. These findings suggest that similar neurotransmitter mechanisms operate in different brain regions in order to regulate memory consolidation processes; however, there is a specialization of these brain regions in relation to different types or components of memory.
Assuntos
Encéfalo/fisiologia , Habituação Psicofisiológica/fisiologia , Memória/fisiologia , Receptores de GABA-A/fisiologia , Receptores Muscarínicos/fisiologia , Receptores de N-Metil-D-Aspartato/fisiologia , 2-Amino-5-fosfonovalerato/farmacologia , Animais , Habituação Psicofisiológica/efeitos dos fármacos , Masculino , Memória/efeitos dos fármacos , Picrotoxina/farmacologia , Ratos , Ratos Wistar , Escopolamina/farmacologiaRESUMO
The immediate post-training microinjection of the N-methyl-D-aspartate receptor antagonist amino-5-phosphonopenmtaanoic acid (5 ug) or of scopolamine, the cholinergic muscarinic antagonist (2 ug), into the dorsal hippocampus of rats caused retrograde amnesia for habituation to a novel environment, as measured by the number of rearings and crossings performed in a test session. In contrast, picrotoxin (0.08 ug), the indirect GABA-A antagonist, caused retrograde memory facilitation. Receptor agonist administered into the hippocampus had effects opposite to those of the respective antagonists: glutamate (5 ug) and oxotremorine (2 ug) enhanced memory and muscimol (0.03 ug) was amnestic. Aminophosphonopentanoic acid, scopolamine and picrotoxin had no effect when injected into the amygdala mor medial septum. Our result contrasted with the recent report of an inhibitory avoidance task in which these drugs, at the doses used here, were effective when injected post-training into any of the three structures. These findings suggest that similar neurotransmitter mechanisms operate in different brain regions in order to regulate memory consolidation processes; however, there is a specialization of these brain regions in relation to different types or components of memory
Assuntos
Tonsila do Cerebelo , Habitação , Hipotálamo , Memória , Receptores Colinérgicos , Receptores de GABA-A , Receptores de N-Metil-D-AspartatoRESUMO
A test for recent memory was developed using non-verbal material. The present report describes a series of experiments conducted to evaluate its reproducibility and the influences of changes in the interval between acquisition and retrieval, and age and level of instruction, and its sensitivity to the integrity of memory function. A total of 114 subjects participated in 5 experiments. The test of recent memory is reproducible over a period of at least 5 months and can be used with training-testing intervals of 24 to 48 h. The performance of the test is affected by age and level of instruction. Moreover, the memory test is sensitive to differences in the integrity of memory function. Thus, the memory test developed in this study may be used to evaluate the effects of behavioral and/or pharmacological manipulations on recent memory in homogeneous groups of subjects.
Assuntos
Memória de Curto Prazo , Testes Neuropsicológicos , Adolescente , Adulto , Idoso , Análise de Variância , Escolaridade , Humanos , Pessoa de Meia-Idade , Retenção PsicológicaRESUMO
A test for recent memory was developed using non-verbal material. The present report describes a series of experiments conducted to evaluate its reproducibility and the influences of changes in the interval between acquisition and tetrieval, and age and level of instruction, and its sensitivity to the integrity of memory function. A total of 114 subjects participated in 5 experiments. The test of recent memory is reproducible over a period of at least 5 months and can be used with training-testing intervals of 24 to 48h. The performance of the test is affected by age and level of instruction. Moreover, thre memory test is sensitive to differences in the integrity of memory function. Thus, the memory test developed in this study may be used to evaluate the effects of behavioral and/or pharmacological manipulations on recent memory in homogeneous groups of subjects
Assuntos
Humanos , Escolaridade , Memória , Testes Neuropsicológicos , Análise de Variância , Escolaridade , Retenção PsicológicaRESUMO
Rats were submitted to a training and a test session in a shuttle avoidance task. In some groups, a second training session was interpolated 2 or 24 hr after the first session. In others, a session of extinction was interpolated 2 or 24 hr after the training session. When the interpolated task was 2 hr after training, training-test interval was 24 hr. When the interpolated task was 24 hr after training, training-test interval was 48 hr. The additional training enhanced, and the extinction depressed, retention test performance. Diazepam, given 30 min prior to the first (or only) training session enhanced the performance of avoidance responses in that session but inhibited it in the subsequent retention test. Diazepam given 90 min after training had no effect on retention. Diazepam given 30 min prior to either the additional training session or the extinction session did not affect performance in that session but cancelled their effects on retention test performance. The effects are related to the previously described prevention by diazepam of interfering effects on memory.
Assuntos
Aprendizagem da Esquiva/efeitos dos fármacos , Diazepam/farmacologia , Memória/efeitos dos fármacos , Retenção Psicológica/efeitos dos fármacos , Animais , Feminino , Ratos , Ratos Endogâmicos , Fatores de TempoRESUMO
Rats were submitted to a training and a test session of shuttle avoidance. Exposure to a session of extinction of this task either 2 or 24 h after training interfered with retention test performance. Exposure to an open field 2, but not 24 h after the avoidance training also interfered with retention. Diazepam blocked the deleterious effect of extinction and of the open field on retention of the avoidance task. Diazepam alone had no effect when given after avoidance training; it did, however, also interfere with retention when given prior to training. It is likely, therefore, that diazepam cancelled the effect of the extinction or of the open field on avoidance retention because of anterograde amnesia (i.e., it prevented the recording of these tasks). The deleterious effect of the open field on retention of shuttle avoidance can be explained by retroactive interference caused by the addition of information. It is not due to a direct influence on retrieval, it is not due to extinction, and it had to be recorded 2 h after training in order to the effective.