Aerobic training lasting for 10 weeks elevates the adipose tissue FABP4, Giα, and adiponectin expression associated by a reduced protein oxidation

OBJECTIVE

The chronic moderate exercise positively alters the systemic glucose homeostasis, enhances the insulin action, and ameliorates the oxidative damage in the skeletal muscle and liver. The aim of this study was to investigate the effect of an intermittent aerobic training on the metabolic parameters of the white adipose tissue in the obese Zucker rats.

METHODS

Obese Zucker rats, 8 week old, were subjected to running on a 4-channel treadmill (1 h/day 5 times/week 20 m/min at maximum) for 10 weeks, except the weekends, (Trained Obese Zucker, TOZ) or were placed to the turned-off treadmill (Sedentary Obese Zucker, SOZ) for the same period. The serum insulin, glucose, and triglyceride were determined. The gene expression of the renin-angiotensin system (RAS) components and selected metabolic parameters were quantified by real-time qPCR in the liver and epididymal and retroperitoneal adipose tissues. The content of the protein carbonyl groups was assayed in the liver and epididymal fat depot.

RESULTS

The gene expression of the adipocyte fatty acid binding protein 4 (FABP4) was significantly elevated in the epididymal and retroperitoneal adipose tissues of the TOZ rats. The level of the adiponectin mRNA was increased in the retroperitoneal adipose tissue while leptin and inhibitory G-protein α mRNA were elevated in the epididymal adipose tissue after exercise. The aerobic training led to a decrease in the amount of protein carbonyl groups in the epididymal adipose depot. Transcription of the angiotensinogen, angiotensin-converting enzyme (ACE), and AT1 receptor genes in the epididymal adipose tissue was not influenced by the exercise. In the liver, only the AT1 receptor gene expression increased significantly. The serum glucose, insulin, and triglycerides concentrations were not changed in the TOZ rats when compared to SOZ animals.

CONCLUSIONS

Data of the present study indicate that an intermittent moderate exercise in the hyperphagic obese Zucker rats lasting for 10 weeks improves some of the morphometric and metabolic parameters of the white adipose tissue and decreases the protein oxidation implying a general beneficial effect of the long-lasting exercising.

[Protection of hypothermic rat liver against gentle manipulation injury]

Hypothermic preservation can increase hepatocyte sensitivity to various insults. Here we studied the hypothesis that hepatocytes are injured by manipulation with cold-preserved liver. Livers from Wistar rats were divided into two groups. In the 1st group (n = 6) the livers were placed after harvesting into a polyethylene (PE) bag. After the preservation period they were placed into the perfusion chamber--developed in our laboratory. Connection of livers from PE bag to the perfusion chamber required a contact manipulation with the liver. This contact manipulation was eliminated in the second group of livers (n = 6) by using the perfusion chamber for preservation. Lavage and perfusion were done in both groups under the same conditions. We found in the lavage solution of livers of the 1st group 2-times more LDH and 3.7-times higher release of TNF-alpha compared to the 2nd group. Further, bile flow of livers from the 1st group during reperfusion was significantly lower compared to the 2nd group (0.179 +/- 0,12 vs 0.398 +/- 0.15 ml/min/g liver). Manipulation with hypothermic liver leads to hepatocyte injury. Our new model of chamber can protect hypothermic liver against manipulation injury and can allow to perform physiological and pharmacological experiments on liver ex vivo.

Improvement of rat liver function by energy repletion after the preservation period: implications for hepatic graft management

We very recently showed (using a blood-free perfusion model) that cold preservation sensitized rat hepatocyte functions to rewarming ischemic injury and that the injury can be prevented by repleting high-energy adenylates in the liver by short-term oxygenated warm reperfusion. Here we investigated whether short-term reperfusion after the preservation period can improve hepatic graft function in a blood reperfusion model. Eighteen-hour cold-preserved rat livers either untreated (Group A) or pretreated by 30-min oxygenated warm reperfusion after preservation (Group B) were subjected to 20-min ischemic rewarming and then reperfused with blood. Livers in Group B compared to Group A exhibited approx. three times increased bile production and bromosulfophthalein excretion, nearly 7-fold decreased swelling, and 1.2-fold improved blood flow. These results suggest that repletion of the energy by short-term oxygenated reperfusion after prolonged preservation may improve markedly initial hepatic graft function.

Protection of the rat liver against rewarming ischemic injury by University of Wisconsin solution

BACKGROUND/AIM

University of Wisconsin (UW) solution has been proven able to prevent liver injury during cold ischemia. During rewarming ischemia, however, the efficacy of this solution in preserving hepatocyte function is unclear. The aim of the present study was to investigate to what extent UW solution protects rat liver during rewarming ischemia.

METHODS

Livers were washed out with cool physiologic saline or with UW solution and subjected to rewarming ischemia for periods of 20 min or 45 min followed by reperfusion using a blood-free perfusion model.

RESULTS

In comparison with controls, ischemia for 20 min in saline-treated livers led to mild depression of hepatocyte function, while UW solution afforded complete protection of the liver. In UW-treated livers, compared with saline-treated livers exposed to ischemia for 45 min, portal flow was slightly but significantly higher, bile production was increased by 62%, and lactate dehydrogenase leakage into the perfusate was reduced by 61%. In an attempt to explain mechanisms of liver protection by UW solution, we found that UW solution inhibited conversion of hypoxanthine into uric acid, but this effect was not associated with decreased degradation of adenine nucleotides in the liver during ischemia. Following 30 min reperfusion, UW solution increased tissue levels of adenosine triphosphate (not significantly) and adenosine diphosphate (significantly). Further, UW solution markedly reduced tumor necrosis factor-alpha release by the liver both after ischemia and after reperfusion.

CONCLUSIONS

These results create the hypothesis that UW solution may protect liver tissue during ischemia in liver surgery as well as during the implantation stage of liver transplantation.