RESUMEN
BACKGROUND: Caloric restriction since birth changes glucose metabolism by the liver in overnight-fasted rats to a fed-like pattern, in which glucose output is large but gluconeogenesis is negligible. It was investigated whether these changes could be a residual effect of the nutritional condition during lactation and what could be the mechanism of such change. METHODS: Newborn Wistar rat pups were arranged in litters of 6 or 12 (G6 and G12). After weaning, the male pups were divided in: G6L and G12 L, fed freely until the age of 90 days (freely-fed groups); G6R and G12R, given 50% of the GL ingestion (food-restricted groups) until 90 days of age; G6RL and G12RL, given 50% of the GL ingestion until 60 days of age and fed freely until 90 days of age (refed groups). The experimental protocols were carried out at the age of 90 days after overnight fasting. Pairs of groups were compared through t test; other statistical comparisons were made with one-way ANOVA with Tukey post hoc text. RESULTS: Caloric restriction was effective in decreasing body and fat weights, total cholesterol and LDL. These effects were totally or partially reversed after 30 days of refeeding (groups GRL). During liver perfusion, the high glucose output of the GRs was further enhanced by adrenaline (1 µM), but not by lactate infusion. In contrast, in groups G6L, G12 L, G6RL and G12RL glycogenolysis (basal and adrenaline-stimulated glucose output) was low and gluconeogenesis from lactate was significant. A twofold increase in liver content of PKA in group G6R suggests that liver sensitivity to glucagon and adrenaline was higher because of caloric restriction, resulting in enhanced glucose output. CONCLUSIONS: As glucose output was not affected by litter size, liver glucose metabolism in the adult rat, in contrast to other metabolic processes, is not a programmed effect of the nutritional condition during lactation. In addition, the increased expression of PKA points to a higher sensitivity of the animals under caloric restriction to glycogenolytic hormones, a relevant condition for glucose homeostasis during fasting.
RESUMEN
Fumonisins (FBs) are mycotoxins produced by Fusarium molds. Several works have shown contamination of maize by this toxin. Fumonisin B1 (FB-1) is found in greatest proportion (about 70%), resistant to several industrialization processes. In that context, the objective of this work was to analyze the effect of administering a diet contaminated with FB- 1 on the morphophysiology of the kidneys of 21-day old male Wistar rats. The animals were divided into 2 groups: G0 (with animals receiving feed free of FBs) and G6 (6mg of FB1 kg-1 of feed). The diet was administered during 42 days. After that period, the animals were placed in metabolic cages for urine collection, blood was collected for analysis of plasma creatinine, and the kidneys were fixed and stained with Masson's trichrome. We observed that FB1 administration did not affect feed intake, body weight gain and animal growth. The normal levels of plasma creatinine suggest that the toxin did not lead to glomerular lesion. There was also no change in water intake, osmolarity and excretion of sodium in urine. However, there was a significant increase in urine volume and potassium excretion in urine, with mild tubulointerstitial changes in the outer cortex for the group receiving the mycotoxin.
Fumonisinas (FBs) são micotoxinas produzidas por fungos do gênero Fusarium. Diversos trabalhos demonstraram a contaminação do milho por essa toxina. A fumonisina B1 (FB-1) é encontrada em maior proporção (cerca de 70%), sendo resistente a vários processos de industrialização. De acordo com este contexto, o trabalho em foco teve como objetivo analisar o efeito da administração de dieta contaminada com FB-1 sobre a morfofisiologia renal de ratos Wistar machos, com 21 dias de idade. Os animais foram divididos em 2 grupos: G0 (ração isenta de FBs) e G6 (alimentados com 6mg de FB1 kg-1 de ração). A dieta foi administrada por 42 dias. Após esse período, os animais foram colocados em gaiolas metabólicas para coleta da urina, o sangue foi coletado para análise da creatinina plasmática, e os rins fixados e corados pelo Tricrômico de Masson. Observou-se que a administração de FB1 não afetou o consumo de ração, o ganho de peso e crescimento dos animais. A normalidade nos níveis da creatinina plasmática sugere que a toxina não induziu lesão glomerular. Não houve alteração na quantidade de água ingerida, na osmolaridade e na excreção urinária do sódio. No entanto houve aumento significativo no volume urinário e na excreção urinária do potássio e presença de alterações tubulointersticiais de intensidade leve no córtex externo, no grupo que recebeu a micotoxina.