Efeito do tratamento com triptofano sobre parâmetros do comportamento alimentar em ratos adultos submetidos à desnutrição neonatal

Abstract

OBJETIVO: Investigou-se os efeitos do tratamento com triptofano sobre o consumo alimentar em ratos adultos, submetidos ou não a desnutrição precoce. MÉTODOS: Sessenta e quatro ratos Wistar machos foram divididos em nutridos (n=32, caseína=17%) e desnutridos (n=32, caseína=8%), de acordo com a dieta materna empregada no período de lactação. Após o desmame, todos os ratos receberam dieta com 23% de proteína. Pesos corporais foram avaliados no sétimo, vigésimo primeiro e septuagésimo dias de vida. Aos setenta dias de idade, cada grupo nutricional foi dividido em subgrupos: Nutrido-Salina (n=16) e Nutrido-Triptofano (n=16), Desnutrido-Salina (n=16) e Desnutrido-Triptofano (n=16). Os grupos receberam diariamente 1,0mL/100g de triptofano, na dose de 50mg/kgP ou salina (0,9%NaCl), durante 14 dias. Neste período foram realizados os estudos dos parâmetros do comportamento alimentar. Posteriormente obteve-se a média do consumo alimentar relativo e a média do ganho de peso relativo. As análises estatísticas foram feitas utilizando os testes t Student e ANOVA seguido de Tukey, com p<0,05. RESULTADOS: As ninhadas de mães alimentadas com dieta hipoproteica mantiveram pesos inferiores comparados com as ninhadas nutridas (p<0,01) até os setenta dias de vida. Os ratos nutridos tratados com triptofano (M=6,88, DP=0,05) reduziram a ingestão alimentar comparados aos nutridos salina (M=7,27, DP=0,08) (p<0,01). Contudo, não houve efeito sobre o ganho de peso. Entre os desnutridos nenhuma diferença foi encontrada. CONCLUSÃO: Nesse estudo, a restrição proteica neonatal alterou a evolução ponderal em ratos. Além disso, a desnutrição precoce tornou os ratos adultos resistentes aos efeitos inibitórios do triptofano sobre a ingestão alimentar.

Influence of protein malnutrition on cutaneous wound healing in rats

“…Proteins ingested or derived from muscle catabolism are metabolized to enzymes, hormones, cytokines, growth factors, and antibody components [23,24]. With protein malnutrition, there is a decrease in the expression of cytokines and growth factors involved in both tissue maintenance processes and in wound healing [12,23]. The results of the present study showed a pauci extracellular matrix in both malnourished animals in both periods of the experiment.…”

“…The MN group was composed of 10 rats from nourished mothers (standard diet containing 17% protein of high biological value), and the N group comprised 10 rats, also obtained from nourished mothers. The day after birth, the mothers of the animals belonging to the MN group were fed a hypoproteic diet (containing 8% protein of high biological value) and water ad libitum during the lactation period (from the 1 st to the 21 st day of life of the pups) [12]. After weaning, the animals continued to receive the same hypoprotein diet and water ad libitum until they were 60-70 days old.…”

Perinatal serotonergic activity: A decisive factor in the control of food intake

“…In the neonatal period, protein malnutrition reduced masticatory efficiency, weakening and delaying masticatory muscle maturation and the associated neuronal circuit [39]. A functional change associated with neonatal malnutrition and food intake seems to decrease the inhibitory effects of tryptophan on food intake in adulthood [40]. This resistance to the inhibitory effects of serotonin has also been observed in malnourished animals in gestation and lactation when submitted to acute fenfluramine administration [37].…”

“…Perinatal protein malnutrition seems to reduce weight gain and food intake in rats [37][38][39][40]. These animals gain less weight as they grow and have lower weight in adulthood.…”

“…The interaction between nutrition in the critical development period, serotonin action, and repercussions in adulthood has been documented by many researchers [2,9,[37][38][39][40]. Perinatal malnutrition is one of the environmental factors responsible for structural and functional changes in central nervous system development, such as fewer neurons, and changes in neuronal shape and neurotransmitter levels [2,41].…”