Capacidade aeróbia de ratos alimentados com dieta rica em frutose

Muscle glycogen metabolism changes in rats fed early postnatal a fructose-rich diet after maternal protein malnutrition: effects of acute physical exercise at the maximal lactate steady-state intensity

BACKGROUND

The objective was to evaluate the muscle glucose metabolism in rats fed a fructose-rich diet after fetal protein malnutrition, at rest and after acute physical exercise at maximal lactate steady-state intensity.

METHODS

The male offspring born of mothers fed on a balanced or low-protein diet were split in four groups until 60 days: Balanced (B): balanced diet during the whole period; Balanced/Fructose (BF): balanced diet in utero and fructose-rich diet after birth; Low protein/Balanced (LB): low-protein diet in utero and balanced diet after birth; Low protein/Fructose (LF): low protein diet in utero and fructose-rich diet after birth.

RESULTS

Acute physical exercise reduced the muscle glycogen concentrations in all groups, although the LF group showed higher concentrations at rest. There was no difference among the groups in the glucose uptake and oxidation rates in the isolated soleus muscle neither at rest nor after acute exercise. However, glycogen synthesis was higher in the LF muscle than in the others at rest. Acute physical exercise increased glycogen synthesis in all groups, and the LF group showed the highest values.

CONCLUSION

The fructose-rich diet administered in rats after fetal protein malnutrition alters muscle glycogen concentrations and glycogen synthesis in the rest and after acute exercise at maximal lactate steady-state intensity.

Metabolic responses to acute physical exercise in young rats recovered from fetal protein malnutrition with a fructose-rich diet

BACKGROUND

Malnutrition in utero can "program" the fetal tissues, making them more vulnerable to metabolic disturbances. Also there is association between excessive consumption of fructose and the development of metabolic syndrome. However, there is little information regarding the acute effect of physical exercise on subjects recovered from malnutrition and/or fed with a fructose-rich diet. The objective of this study was to evaluate the metabolic aspects and the response to acute physical exercise in rats recovered from fetal protein malnutrition with a fructose-rich diet.

METHODS

Pregnant Wistar rats were fed with a balanced (B) diet or a low-protein (L) diet. After birth and until 60 days of age, the offspring were distributed into four groups according to the diet received: B: B diet during the whole experiment; balanced/fructose (BF): B diet until birth and fructose-rich (F) diet afterwards; low protein/balanced (LB): L diet until birth and B diet afterwards; low protein/fructose (LF): L diet until birth and F diet afterwards.

RESULTS

The excess fructose intake reduced the body weight gain, especially in the BF group. Furthermore, the serum total cholesterol and the LDL cholesterol were elevated in this group. In the LF group, the serum total cholesterol and the muscle glycogen increased. Acute physical exercise increased the serum concentrations of glucose, triglycerides, HDL cholesterol and liver lipids and reduced the concentrations of muscle glycogen in all groups.

CONCLUSION

An excess fructose intake induced some signs of metabolic syndrome. However, protein malnutrition appeared to protect against the short term effects of fructose. In other hand, most responses to acute physical exercise were not influenced by early malnutrition and/or by the fructose overload.

Medidas murinométricas e eficiência alimentar em ratos provenientes de ninhadas reduzidas na lactação e submetidos ou não ao exercício de natação

INTRODUÇÃO: Excesso de alimentação no início da vida pode modificar persistentemente consumo e peso corporal. Adoção de exercício físico é uma estratégia útil para evitar excessivo ganho de peso. OBJETIVO: Avaliar o crescimento corporal e a eficiência alimentar em ratos provenientes de ninhada reduzida no aleitamento. MÉTODOS: Ao terceiro dia de vida, ninhadas foram formadas com quatro (GN4) ou 10 animais (GN10), (n = 25). Ao desmame, ratos machos Wistar permaneceram em gaiolas individuais, e, aos 60 (± 2) dias foram subdivididos em sedentários (SED) e exercitados (NAT), formando quatro grupos: GN4SED, GN10SED, GN4-NAT e GN10NAT. Avaliou-se o peso, ganho de peso e taxa específica de ganho de peso, gordura epididimal, índices de massa corporal e Lee, consumo e eficiência alimentar, glicemia e lactemia. RESULTADOS: Aos 21 dias, o GN4 apresentava peso corporal 52% acima do GN10 (P = 0,001). Contudo, aos 30 e 60 dias os pesos não diferiram. Ao final do período, GN10NAT demonstrou menor peso (356,82 ± 23,04) que GN10SED (409,28 ± 17,30). Mas GN4NAT possuía maior peso (417,85 ± 37,91) que GN4SED (413,69 ± 57,45) e GN10NAT. O GN4 exibiu elevada taxa de ganho de peso na lactação, mas, redução da mesma pós-desmame. Independente do tamanho da ninhada, a taxa de ganho de peso reduz com o aumento da idade. Ao final do período, glicemia, gordura epididimal total e relativa, e os índices de Lee e IMC não diferiram entre os grupos. Os valores de lactato antes e após o exercício condizem com esforço de intensidade moderada. Na periadolescência, GN4 apresentou menor ingestão de alimentos, mas sem diferenças na vida adulta. CONCLUSÃO: A redução da ninhada no aleitamento não alterou o peso corporal ou ingestão alimentar persistentemente. Entretanto, o protocolo de natação foi eficaz em reduzir o ganho de peso em animais controles, mas não naqueles de ninhada reduzida.

Aerobic capacity of rats recovered from fetal malnutrition with a fructose-rich diet

The objective of this study was to analyze the aerobic capacity, through the maximal lactate steady-state (MLSS) protocol, of rats subjected to fetal protein malnutrition and recovered with a fructose-rich diet. Pregnant adult Wistar rats that were fed a balanced (17% protein) diet or a low-protein (6% protein) diet were used. After birth, the offspring were distributed into groups according to diet until 60 days of age: balanced (B), balanced diet during the whole experimental period; balanced-fructose (BF), balanced diet until birth and fructose-rich diet (60% fructose) until 60 days; low protein-balanced (LB), low-protein diet until birth and balanced diet until 60 days; and low protein-fructose (LF), low protein diet until birth and fructose-rich diet until 60 days. It was verified that the fructose-rich diet reduced body growth, mainly in the BF group. There was no difference among the groups in the load corresponding to the MLSS (B, 7.5+/-0.5%; BF, 7.4+/-0.6%; LB, 7.7+/-0.4%; and LF, 7.7+/-0.6% relative to body weight). However, the BF group presented higher blood lactate concentrations (4.8+/-0.9 mmol.L(-1)) at 25 min in the load corresponding to the MLSS (B, 3.2+/-0.9 mmol.L(-1); LB, 3.4+/-0.9 mmol.L(-1); and LF, 3.2+/-1.0 mmol.L(-1)). Taken together, these results indicate that the ability of young rats to perform exercise was not altered by intrauterine malnutrition or a fructose-rich diet, although the high fructose intake after the balanced diet in utero increased blood lactate during swimming exercises in rats.