The effects of chlorogenic acid (CA) on hepatic glucose output, blood glucose levels and on glucose tolerance were analysed. Hepatic uptake of CA and its effects on hepatic catabolism of L-alanine and glucose-6-phosphatase (G-6-Pase) activity were also evaluated. CA (1 mM) inhibited about 40% of G-6-Pase activity (p < 0.05) in the microsomal fraction of hepatocytes, but no effect was observed on production of glucose from gluconeogenesis or on L-alanine catabolism, at various concentrations of CA (0.33, 0.5 and 1 mM), in liver perfusion experiments. Since there were indications of a lack of uptake of CA by the liver, it is possible that this compound did not reach sufficiently high intracellular levels to inhibit the target enzyme. Accordingly, intravenous administration of CA also failed to provoke a reduction in blood glucose levels. However, CA did promote a significant reduction (p < 0.05) in the plasma glucose peak at 10 and 15 min during the oral glucose tolerance test, probably by attenuating intestinal glucose absorption, suggesting a possible role for it as a glycaemic index lowering agent and highlighting it as a compound of interest for reducing the risk of developing type 2 diabetes.
Blood metabolic parameters of Walker-256 tumour-bearing rats, on days 5, 8, 11 and 14 after implantation of tumour, were compared with those of rats without tumour fed ad libitum (free-fed control) or with reduced feeding (pair-fed control), similar to the anorexic tumour-bearing rats. Cachexia parameters and tumour mass also were investigated. In general, especially on day 14 after implantation of tumour, there was reduction of body mass, gastrocnemius muscle mass, food intake and glycemia and increase of blood triacylglycerol, free fatty acids, lactate and urea, compared with free-fed controls rats. These changes did not occur in pair-fed control, except a slight reduction of glycemia. Pair-fed control showed no significant changes in blood cholesterol and glycerol in comparison with free-fed control, although there was reduction of cholesterol and increase of blood glycerol on day 14 after tumour implantation compared with pair-fed control. The results demonstrate that, besides the characteristic signs of the cachexia syndrome such as anorexia, weight loss and muscle catabolism, Walker-256 tumour-bearing rats show several blood metabolic alterations, some of which begin as early as day 5 after implantation of tumour, and are accentuated during the development of cachexia. Evidence that the alterations of blood metabolic parameters of tumour-bearing rats were not found in pair-fed control indicate that they were not caused by decreased food intake. These changes were probably mediated by factors produced by tumour or host tissue in response to the presence of tumour.
Background/Aims: The main purpose of this study was to investigate the effects of celecoxib and ibuprofen, both non-steroidal anti-inflammatory drugs (NSAIDs), on the decreased gluconeogenesis observed in liver of Walker-256 tumor-bearing rats. Methods: Celecoxib and ibuprofen (both at 25 mg/Kg) were orally administered for 12 days, beginning on the same day when the rats were inoculated with Walker-256 tumor cells. Results: Celecoxib and ibuprofen treatment reversed the reduced production of glucose, pyruvate, lactate and urea from alanine as well as the reduced production of glucose from pyruvate and lactate in perfused liver from tumor-bearing rats. Besides, celecoxib and ibuprofen treatment restored the decreased ATP content, increased triacylglycerol levels and reduced mRNA expression of carnitine palmitoyl transferase 1 (CPT1), while ibuprofen treatment restored the reduced mRNA expression of peroxisome proliferator-activated receptor alpha (PPARα) in the liver of tumor-bearing rats. Both treatments tended to decrease TNFα, IL6 and IL10 in the liver of tumor-bearing rats. Finally, the treatment with celecoxib, but not with ibuprofen, reduced the growth of Walker-256 tumor. Conclusion: Celecoxib and ibuprofen restored the decreased gluconeogenesis in the liver of Walker-256 tumor-bearing rats. These effects did not involve changes in tumor growth and probably occurred by anti-inflammatory properties of these NSAIDs, which increased expression of genes associated with fatty acid oxidation (PPARα and CPT1) and consequently the ATP production, normalizing the energy status in the liver of tumor-bearing rats.
Hepatic responsiveness to gluconeogenic substrates during insulininduced hypoglycemia was investigated. For this purpose, livers were perfused with a saturating concentration of 2 mM glycerol, 5 mM Lalanine or 5 mM L-glutamine as gluconeogenic substrates. All experiments were performed 1 h after an ip injection of saline (CN group) or 1 IU/kg of insulin (IN group). The IN group showed higher (P<0.05) hepatic glucose production from glycerol, L-alanine and L-glutamine and higher (P<0.05) production of L-lactate, pyruvate and urea from L-alanine and L-glutamine. In addition, ip injection of 100 mg/kg glycerol, L-alanine and L-glutamine promoted glucose recovery. The results indicate that the hepatic capacity to produce glucose from gluconeogenic precursors was increased during insulin-induced hypoglycemia.
PGZ and PGZ+INS improved INS peripheral sensitivity, possibly by decreasing blood free fatty acids, and reduced fat tissue wasting and body weight loss in small tumor-bearing rats. The results suggest clinical benefits of PGZ in preventing INS resistance, adipose tissue wasting and weight loss when the tumor is small, i.e., in less severe cachexia.
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