RESUMO
In order to study the lasting consequences of brain changes caused by early malnutrition, rats were fed a protein-deficient diet from birth until 49 days of age and a balanced diet from day 50 to day 70. At 49 and 70 days of age, independent groups of animals were tested in the locomotor activity, step-down inhibitory avoidance, and flinch-jump nociceptive tests. Also, at 49 days of age, malnourished and control rats were sacrificed in order to evaluate the weight of brain regions. Malnourished rats had lower body and brain weights (telencephalon and brain stem) than control rats. Malnourished rats also showed less locomotor activity at the beginning of the test session, lower flinch and jump thresholds, and longer step-down latencies than control animals. Chlordiazepoxide (5 mg/kg, IP) shortened step-down latency of well-nourished rats, but was ineffective in malnourished rats. These and previously reported results indicate that early protein malnutrition causes long-lasting impairment of neuronal systems underlying emotional behavior.
Assuntos
Aprendizagem da Esquiva/efeitos dos fármacos , Clordiazepóxido/farmacologia , Distúrbios Nutricionais/psicologia , Animais , Ansiedade/psicologia , Peso Corporal/efeitos dos fármacos , Ingestão de Alimentos/efeitos dos fármacos , Eletrochoque , Masculino , Atividade Motora/efeitos dos fármacos , Nociceptores/fisiologia , Tamanho do Órgão/efeitos dos fármacos , Dor/psicologia , Ratos , Ratos Endogâmicos , Limiar Sensorial/efeitos dos fármacosRESUMO
In order to study the functional consequences of brain changes caused by early malnutrition, rats were fed a protein-deficient diet from birth until 49 days of age and a balanced diet from day 50 to day 70. The animals were submitted to a step-down inhibitory avoidance task and to the flinch-jump nociceptive test at 49 and 70 days of age. Malnourished rats showed longer step-down latencies and lower flinch and jump thresholds than eutrophic animals. Chlordiazepoxide (5 mg/kg, ip) shortened step-down latency of well-nourished rats, whereas it failed to do so in malnourished rats. Since well-nourished animals also became resistant to chlordiazepoxide when tested with a higher shock intensity, generating avoidance latencies comparable to those of malnourished animals, we conclude that the drug resistance induced by malnutrition may be secondary to enhanced pain sensitivity and/or reactivity.
Assuntos
Clordiazepóxido/farmacologia , Reação de Fuga/efeitos dos fármacos , Distúrbios Nutricionais/fisiopatologia , Animais , Encéfalo/fisiopatologia , Masculino , Desnutrição Proteico-Calórica/fisiopatologia , Ratos , Ratos EndogâmicosRESUMO
In order to study the functional consequences of brain changes caused by early malnutrition, rats were fed a protein-deficient diet from birth until 49 days of age and a balanced diet from day 50 to day 70. The animals were submitted to a step-down inhibitory avoidance task and to the flinch-jump nociceptive test at 49 and 70 days of age. Malnourished rats showed longer step-down latencies and lower flinch and junp theresholds than eutrophic animals. Chlordiazepoxide (5 mg/Kg, ip) shortened step-down latency of well-nourished rats, whereas it failed to do so in malnourished rats. Since well-nourished animals also became resistant to chlordiazepoxide when tested with a higher shock intensity, generating avoidance latencies comparable to those of malnourished animals, we conclude that the drug resistance induced by malnutrition may be secondary to enhanced pain sensitivity and/or reactivity