α-Amino [1-14C] isobutyric acid ([14C] AIB) is a non-metabolizable analogue of alanine, the principal amino acid released by muscle in catabolic states and the major gluconeogenic amino acid in the liver. Phosphoenolpyruvate carboxykinase (PEPCK) is a rate-limiting enzyme in gluconeogenesis. Many factors, such as hormones and cytokines, have effect on both uptake of alanine by the liver and the hepatic PEPCK activity. The aim of this study was to evaluate the cooperative effect of recombinant mouse IL-6 (rmIL-6) and recombinant human IL-1 (rhIL-1) with glucagon on [14C]AIB uptake and PEPCK activity in cultured rat hepatocytes. Our data showed that rmIL-6 and glucagon increased [14C]-AIB uptake individually in a dose-dependent manner and had a significant additive effect on the uptake in rat hepatocytes. However, rhIL-1 had no effect on [14C] AIB uptake. Regarding PEPCK, rmIL-6 and rhIL-1 had no effect on the activity of PEPCK in rat hepatocytes. But both rmIL-6 and rhIL-1 significantly inhibited the stimulative effect of glucagon on hepatic PEPCK activity of the rats.
The structural and functional changes of mitochondrial monoamine oxidase (MAO) in livers of rats fed a selenium (Se)-deficient diet from an endemic area of Keshan disease were investigated. The results indicate that after intake of the Se-deficient diet for 12-14 weeks, MAO activity and lipid fluidity in the mitochondrial membranes were significantly lower than those of the control rats; on the contrary, MAO degradation and lipid peroxides were significantly higher. Concomitantly, Se content and glutathione peroxidase (GPX) activity in hepatic homogenates of Se-deficient rats markedly decreased. These changes could be prevented or returned to the control levels when the rats were fed the same diet but one supplemented with 0.5mg/kg Na2SeO3. In vitro, we also showed that adding 0.5ppm Na2SeO3 in hepatic submitochondria could significantly decrease MAO degradation induced by the intermediates of lipid peroxidation generated through radiolysis of submitochondria with a 60Co source. Our results suggest that Se may be important for preventing lipid peroxidation in hepatic mitochondrial membranes, thus maintaining structural and functional integrity of MAO.
In a previous study, we detected in human serum two immunoreactive bFGF-like (bFGF-LI) substances, a high-molecular-weight form (designated as HMW-bFGF-LI) and a 16-kDa form. In this current work, we partially purified these two Immunoreactive bFGFs from sera of patients with breast cancer by heparin-affinity chromatography and gel filtration, and further investigated their immunochemical properties and biological activities. As a result, we found that the antigenicity of the two immunoreactive bFGFs was identical to that of recombinant bFGF. And the mitogenic activity toward BALB/c3T3 fibroblasts of the 16-kDa bFGF-LI was equal to that of recombinant bFGF, whereas the mitogenic effect of HMW-bFGF-LI was weak. The mitogenic activity of the two Immunoreactive bFGFs was completely inhibited by the addition of neutralizing antibody. The mitogenic activity of the 16-kDa bFGF-LI was increased by the addition of dexamethasone, whereas that of HMW-bFGF-LI was unaffected by the drug.
We have presented several lines of evidence suggesting that in rats the neurons in the hypothalamic suprachiasmatic nucleus are involved in the regulation of glucose metabolism. There are neurons containing vasoactive intestinal peptide (VIP)-like immunoreactive substance in the suprachiasmatic nucleus, and we thought that these VIP neurons might regulate glucose metabolism. To investigate this possibility, we examined the effect of VIP injection into the lateral cerebral ventricle or the peritoneal cavity on the blood glucose level. We found that Intracranial injection of VIP into unanesthetized rats elicited hyperglycemia and hyperglucagonemia without hyperinsulinemia, although these responses showed no photoperiodicity. We also found that intraperitoneal injection of the same dose of VIP had no effect on the plasma concentrations of glucose and insulin. These facts suggest that VIP is involved in the regulation of glucose metabolism governed by the suprachiasmatic nucleus.
The objectives of the present investigation were to examine the effect of ischemia and reperfusion on superoxide anion (O-2) generation, leukocyte infiltration, edema, and erosion (injury) in the rat gastric mucosa. Ischemia of 5-, 15-, and 30-min duration was applied to the gastric tissue followed by 2.5h of reperfusion. O-2 generation in the gastric mucosa in situ during reperfusion was measured by use of a highly sensitive luminescence reagent, 2-methyl-6-phenyl-3, 7-dihydroimidazo [1.2-α] pyrazin-3-one (CLA) and a photon counting technique. Leukocyte infiltration, edema, and erosion were determined by examining gastric mucosa tissue post-reperfusion. O-2 generation, the extent of edema, and erosion all increased with the duration of Ischemia, but leukocyte infiltration was maximum after an ischemia of 15-min duration, with a corresponding reperfusion period of 15min. Administration of an O-2 scavenger, superoxide dismutase (SOD), effectively abolished O-2 detection and markedly reduced the extent of edema but was virtually ineffective on leukocyte infiltration and mucosal erosion. Similarly, the xanthine oxidase inhibitor allopurinol markedly supressed O-2 detection, edema, and mucosal erosion, but was ineffective against leukocyte infiltration into the mucosal tissue. These observations suggest that more than one mechanism contributes to tissue injury induced by ischemia and reperfusion in this model.
The effect of chronic ethanol administration on intestinal uptake of D-glucose, L-glycine, and L-leucine was studied in rats maintained on rat pellet (RP) or semisynthetic diets rich in either saturated (coconut oil; CCO) or unsaturated (n-6, corn oil; CO or n-3, fish oil; FO) triacylglycerols. The fish oil diet enhanced sodium-coupled uptake of glucose and glycine as compared with the diets containing RP, CCO, or CO. The rate of Na+-dependent leucine uptake was in the order of RP=CO<CCO<FO. In general, the solute uptake was not affected by dietary oils in the absence of sodium ions. Chronic ethanol administration to rats fed RP, CO, and FO reduced Na+-dependent glucose and glycine uptake. The CCO diet abolished the ethanol-induced decrease in glucose and glycine uptake. Leucine uptake was decreased in ethanoltreated CCO or FO groups only. Sodium independent uptake of the solutes remained unaltered upon ethanol ingestion. Kinetic studies revealed differences in the values of maximum velocity and affinity constants. These observations suggest that the type of dietary lipids has an important bearing on the absorptive properties of rat small intestine in response to ethanol.
In the present study we report that protein kinase C (PKC) inhibitors, H-7 and chelerythrine chloride, inhibit the cisplatin- or lipopolysaccharide (LPS)-induced activation of murine peritoneal macrophages to the tumoricidal state. Similarly, the tumoricidal activity was also downregulated by protein tyrosine kinase (PTK) inhibitors, genestein and lavendustin A. The production of interleukin-1 (IL-1) and tumor necrosis factor (TNF) by cisplatin- or LPS-treated macrophages was also inhibited by both PKC and PTK inhibitors. These findings suggest the involvement of PKC and PTK in the activation of murine peritoneal macrophages with cisplatin and LPS.