The role of atorvastatin in bone metabolism in male albino Wistar rats.

OBJECTIVE: Statins have been widely used for the treatment of hypercholesterolemia, and recent studies have shown that these drugs also affect bone metabolism. The aim of this experiment was to follow the effect of atorvastatin on bone metabolism in male albino Wistar rats. METHODS: Our study was carried out on 16 rats (240 +/- 10g) which were randomly divided into 2 groups of 8 animals. The control group (CO) was given aqua pro injectione (0.2 mL/100 g BW; gavage) and the experimental group atorvastatin suspension (AT; 0.3 mg in 0.2 mL aqua pro inj./100 g BW; gavage) daily for 8 weeks. We examined serum markers of bone turnover using ELISA - C-terminal crosslinking telopeptide of type I collagen (CTX-I), total osteocalcin (total OC), procollagen type I N propeptide (PINP) and bone alkaline phosphatase (bone ALP). We investigated bone morphogenetic protein-2 (BMP-2) in the proximal tibia using Western blot analysis. Additionally, we measured bone mineral density (BMD). The femurs were used for a three-point bending test and compression test of the femoral neck. RESULTS: After 8 weeks of atorvastatin administration, a significant decrease was found in serum level of bone ALP to 30% vs. CO (p = 0.005). PINP, CTX-I and OC did not change significantly. The expression of BMP-2 was increased. There were no significant differences in BMD measurements, three-point bending test or compression test of the femoral neck. CONCLUSIONS: Our results suggest that atorvastatin has a positive effect on bone metabolism in rats by maintenance of BMD and the biomechanical characteristics of bone. Atorvastatin influenced bone metabolism by decreasing bone ALP, and probably in consequence increasing expression of BMP-2 in rats.

Mild hypothermia attenuates changes in respiratory system mechanics and modifies cytokine concentration in bronchoalveolar lavage fluid during low lung volume ventilation.

Hypothermia was shown to attenuate ventilator-induced lung injury due to large tidal volumes. It is unclear if the protective effect of hypothermia is maintained under less injurious mechanical ventilation in animals without previous lung injury. Tracheostomized rats were randomly allocated to non-ventilated group (group C) or ventilated groups of normothermia (group N) and mild hypothermia (group H). After two hours of mechanical ventilation with inspiratory fraction of oxygen 1.0, respiratory rate 60 min(-1), tidal volume 10 ml x kg(-1), positive end-expiratory pressure (PEEP) 2 cm H2O or immediately after tracheostomy in non-ventilated animals inspiratory pressures were recorded, rats were sacrificed, pressure-volume (PV) curve of respiratory system constructed, bronchoalveolar lavage (BAL) fluid and aortic blood samples obtained. Group N animals exhibited a higher rise in peak inspiratory pressures in comparison to group H animals. Shift of the PV curve to right, higher total protein and interleukin-6 levels in BAL fluid were observed in normothermia animals in comparison with hypothermia animals and non-ventilated controls. Tumor necrosis factor-alpha was lower in the hypothermia group in comparison with normothermia and non-ventilated groups. Mild hypothermia attenuated changes in respiratory system mechanics and modified cytokine concentration in bronchoalveolar lavage fluid during low lung volume ventilation in animals without previous lung injury.

Colon submucosal microdialysis: a novel in vivo approach in barrier function assessment - a pilot study in rats.

During shock, prognosis of a patient depends largely on intestinal barrier function. The potency of gut epithelium to represent an obstacle to toxins is determined by the blood supply. All established methods of mucosal function determination necessitate the functional involvement of bloodstream. Microdialysis allows monitoring of extracellular substances in the gut submucosa, but its potential use for gut barrier integrity assessment is unknown. Twelve rats underwent perfusion of the descending colon either with 20 % ethanol or control medium (vehicle). Both media contained equal amounts of a radioactive tracer substance ((51)Cr-EDTA). Mucosal permeability for (51)Cr-EDTA was assessed by microdialysate to luminal perfusate activity ratios. Sampling was performed using the colon submucosal microdialysis technique. The group subjected to ethanol treatment had profound macro- and microscopical alterations in perfused colonic segment associated with a significant increase in tracer permeability during ethanol exposure (2.354+/-0.298 % for ethanol as opposed to 0.209+/-0.102 % for control group, p 0.01), which remained elevated for 60 min after cessation of ethanol administration (3.352+/-0.188 % for ethanol compared to 0.140+/-0.0838 % for the control group, p 0.001). Submucosal microdialysis with radioactive tracer substance can be considered a feasible and advantageous alternative of gut barrier function estimation. Parallel monitoring of local tissue chemistry with this method remains a challenge in the future.

The differences in selected biochemical markers and histological findings after bile duct ligation in male and female rats.

To study the correlation between the degree of histopathological changes in the liver and selected biochemical tests after bile duct ligation (BDL) in male and female Wistar rats. Rats were divided into 4 groups. Laparotomized male rats (M-LAP), male rats with BDL (M-BDL), laparotomized female rats (F-LAP) and female rats with BDL (F-BDL). Liver bioptic samples were taken 7 and 14 days after operations and were cultivated 24 hours under standard conditions. TNF-alpha and IL-6 (pg/ml) concentrations were estimated in cell culture supernatants. Rats were sacrificed 14 days after operations, histological evaluation of liver tissue was performed, and serum activity of alanine-transaminase (ALT) and gamma-glutamyl transferase (GMT) (microkat/l) and estradiol concentration (EST) (pmol/1) were estimated. Results are presented as median (cytokines, estradiol) or mean +/- SEM. IL-6 concentration in cell culture supernatants was 7 days after the operation 1495 pg/ml in M-BDL and 1050 pg /ml in F-BDL, but were not detected in M-LAP and F-LAP. TNF-alpha concentration in supernatants was detected in all groups and was not significantly higher in male rats in comparison with female rats. M-BDL group had higher activity of ALT (1.5+/-0.1) and GMT (1.24+/-0.38) in comparison with F-BDL (ALT - 1.24+/-0.38, GMT - 0.98+/-0.38). Estradiol concentrations were detected in BDL groups, male rats 175 pmol/l and female rats 543 pmol/l. Although ALT and GMT activities and TNF-alpha and IL-6 concentrations were higher in male rats histopathological findings have shown slightly more advanced fibrotic and inflammatory changes in female rats.

Course of liver regeneration after partial hepatectomy in rats treated with dialysates of intact organs.

A number of growth phenomena observed in vitro have shown that cells, at high densities, produce and release substances which, when they have reached a given concentration, arrest further growth. In vivo, these possibilities can be studied on the model of rapid regeneration of the rat liver after 65-70% partial hepatectomy (PH). We evaluated the course of liver regeneration after PH in animals treated with dialysates (DIA) of intact rat tissues. In addition to kidney and lymph node DIA, we were particularly interested in the effect of liver and spleen DIA. The experiments were carried out on male rats weighing 210-240 g. The relevant DIA was administered 24 h prior to PH; the controls were given physiological saline. The animals were killed just before PH and 24, 48, 30 and 72 h and 14 days after. DIA obtained from intact liver tissue inhibited the regeneration process induced by PH and its effect persisted 48 h after PH. Compared with the controls and with the rats given kidney DIA, DNA synthesis in the liver 24 h after PH was reduced to 77%. After spleen DIA, several (still hypothetical) factors probably acted together synergically (factors belonging to the immune system--RES--and spleen-produced factors capable of promoting proliferation of the hepatocytes--the "portal blood factor"). We arrived at this conclusion from an evaluation of liver DNA synthesis 24 h after 24h after PH, when synthesis was altogether markedly raised, but attained far higher values after the administration of spleen DIA.(ABSTRACT TRUNCATED AT 250 WORDS)

Course of liver regeneration after partial hepatectomy in rats treated with dialysates obtained 17 hours after partial hepatectomy.

Various theories have been put forward to explain the regenerative capacity of liver tissue induce by partial hepatectomy (PH). One of them presumes the existence of humoral factors stimulating proliferation of the liver tissue. We evaluated the course of liver regeneration after 65-70% PH as influenced by dialysates (DIA) of the organs of a rat killed 17 h after PH. In addition to kidney DIA, we were particularly interested in the effect of liver and spleen DIA. The experiments were carried out on rats weighting 310-370 g. Kidney, liver or spleen dialysate was administered subcutaneously and the rats were killed 12 or 24 h later by exsanguination from the abdominal aorta. In further rats, PH was performed 24 h after administering DIA and the rat were killed 18, 24, 30, 48 and 72 h after the operation. The initiation of liver regeneration was stimulated by all the given DIA, but especially by liver DIA. The faster onset of liver regeneration 18 h after PH in rats given spleen DIA is interesting. DIA did not greatly affect the hepatocytes of intact liver, but accelerated the initiation of liver regeneration after PH by synchronizing the cell cycle of proliferating hepatocytes. DIA obtained 17 h after PH contained substances which primarily stimulated liver DNA synthesis. From the changes in inhibition of the migration of spleen macrophages in the medium containing liver antigens, and from the circulating immunocomplex values, we conclude that DIA activation of the immune system, a well as the hepatic stimulator substance contained in the DIA, participates in acceleration of the liver regeneration process.