Radioprotective action of a GGS-10 gaseous hypoxic mixture on the DNA supramolecular complex of normal tissues and sarcoma 45 of rats

Gas hypoxic mixture (GHM-10) inhaled by rats during gamma-irradiation (2 to 20 Gy) effectively protects the supramolecular complex of DNA (SC DNA) in bone marrow and spleen, but fails to protect this complex in sarcoma 45. GHM-10 itself has been shown to induce rapid and prolonged, but irreversible, decrease in SC DNA elastic viscosity in normal tissues.     

Thermogenic effects of dihydrocodeine in the rat

The object of this study was to assess the effects of dihydrocodeine on thermogenesis and brown adipose tissue activity in the rat from measurements of oxygen consumption and blood flow. Acute injection of dihydrocodeine tartrate (s.c.) stimulated resting oxygen consumption (VO2) in Sprague-Dawley rats in a dose-dependent manner (0.5-50 mg/kg), with a peak response (40-45% increase) occurring at 10-25 mg/kg. This effect was also observed in urethane-anaesthetized rats (although the effect was reduced) and in conscious animals following gastric intubation with the drug. Pretreatment of rats with either a beta-adrenergic antagonist (propranolol, 20 mg/kg), ACTH (4 g/kg), or an opiate antagonist (WIN44441-1, 2 mg/kg) significantly reduced the response to dihydrocodeine, whereas corticosterone injection (5 mg/kg) enhanced the effect. Surgical adrenalectomy or hypophysectomy (HYPX) almost completely abolished the thermogenic effect of dihydrocodeine. Dihydrocodeine also stimulated VO2 in lean (58% increase) and genetically obese Zucker rats (69% increase), and in both Zucker genotypes these responses were only slightly affected by HYPX, but enhanced in HYPX rats treated daily with corticosterone (1 mg/kg). Tissue blood flow, assessed from the distribution of radiolabelled microspheres, was unaffected in white adipose tissue, skeletal muscle, testes, kidney, brain, and liver (arterial supply) after a single injection of dihydrocodeine (25 mg/kg), but flow to interscapular and perirenal brown adipose tissue was increased by 9- to 10-fold. Surgical sympathectomy of brown adipose tissue prevented the increase in blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)     

Modification of DNA-specific methylation in tissues of healthy and tumor bearing (sarcoma 45) rats under the effect of an active alkylating cancerolytic agent

The content of 5-methyl cytosine (5-MC) in the DNA preparations from organs and tissues of healthy and tumour-bearing (sarcoma 45) rats and the effect of an alkylating cancerolytic agent on DNA methylation in vivo were studied. The 5-MC content in the DNA preparations from liver, spleen and testicles of tumour-bearing rats and tumour cells was increased, the maximal increase being observed in liver and spleen DNAs (1,71 and 1,70 mol.%, respectively) and in sarcoma DNA (1,93 mol.%) on the 8th post-inoculation day. On the 8th and 15th day following daily injections of the cancerolytic agent the 5-MC content in the DNAs from liver and spleen of the control animals was decreased in a number of cases almost down to normal level (1,00 mol.%). Tumour DNA did not differ from normal tissue DNA with respect to Tmelt and GC content; however, its differential melting curve revealed an additional "shoulder" within the temperature range of 56--60 degrees, which was partly removed after addition of the cancerolytic agent. It was assumed that the changes in the methylation level and secondary structure of DNA can be due to the cancerolytic activity of the preparation.     

Protective Effects of Curcumin against Fluoride-Induced Oxidative Stress in the Rat Brain

We examined effects of a plant polyphenolic compound, curcumin, against fluoride-induced oxidative stress in the rat brain. Five experimental groups of male rats (10 animals each) were compared. Animals of these experimental groups were treated with curcumin (10 and 20 mg/kg body mass), vitamin C (10 mg/kg), and sample solvent (0.5 ml) for a week prior to sodium fluoride intoxication. After treatment, rats of the experimental groups, except for the normal control group, were intoxicated with sodium fluoride (600 ppm through drinking water) for a week. Then, brains were collected and homogenized, and activities of superoxide dismutase and catalase and levels of reduced glutathione and lipid peroxidation final products were evaluated in the brain tissue homogenates. Treatment with curcumin prior to fluoride intoxication significantly normalized the above biochemical parameters; the intensity of protective effects of 20 mg/kg curcumin was close to that of vitamin C.     

Stereological study of rat spleen following acute ethanol treatment

To investigate the acute effect of ethanol (4 g/kg, i.p.) on spleen adult female Wistar rats were treated intraperitoneally with: a) ethanol (4 g/kg body wt), b) naltrexone (5 mg/kg body wt) followed 45 minutes later by ethanol (4 g/kg body wt) and c) naltrexone (5 mg/kg body wt) alone. Untreated and saline-treated rats were used as controls. Twenty hours after the ethanol treatment the animals were sacrificed and the spleens were removed. A piece of tissue from the central part of each organ was fixed in Bouin's solution. Paraffin sections were stained with hematoxylin-eosin and analysed using stereological measurements. The volume densities of the following tissue compartments: red pulp, white pulp (divided in follicles, periarterioral lymphatic sheath and marginal zone) and the connective tissue were determined. Stereological analysis also included parameters of follicles: the areal numerical density (the number of follicles per 1 mm2 of tissue section), the numerical density (the number of follicles per mm3 of tissue) and the mean follicle diameter. The immunoarchitecture of the spleen was preserved following acute ethanol treatment. Unlike other parameters that were unaffected, ethanol evoked a decrease in both volume density of follicle and the mean follicle diameter. Naltrexone pretreatment had no influence on ethanol-induced changes. The data obtained indicate that a single dose of ethanol has a profound effect on rat spleen affecting the follicles, but the mechanism of its action remains to be elucidated.     

清脑方对缺血性眩晕大鼠脑损伤的保护作用

目的 初步研究清脑方（Qingnaofang,QNF）对缺血性眩晕大鼠脑损伤的保护作用及其作用机制.方法 采用手术结扎右侧颈总动脉和锁骨下动脉致大鼠右侧半脑不完全脑缺血建立缺血性眩晕大鼠模型.分为模型组,QNF 1.04、0.52、0.26 g/kg组,盐酸地芬尼多15 mg/kg组,银杏叶片5.76 mg/kg组以及假手术组,观察QNF对旋转刺激缺血性眩晕大鼠跳台逃避潜伏期的影响,取材并测定动物缺血侧组织Lac、LDH、SOD、MDA、NO及NOS的含量或活性.结果 （1）与模型组相比,QNF 1.04、0.52、0.26 g/kg组大鼠跳台逃避电击潜伏期分别缩短53.6%（P〈0.01）、33.8%（P〈0.05）、56.5%（P〈0.01）.（2）QNF 1.04、0.52、0.26 g/kg均可显著降低缺血侧脑组织中Lac的含量以及LDH的活力 （P〈0.05,P〈0.01）,降低其TNOS及iNOS活力 （P〈0.01）;QNF 0.52 g/kg剂量能够明显降低缺血侧脑组织中SOD活力;QNF 0.52、0.26 g/kg剂量可显著降低其MDA和NO的含量 （P〈0.05,P〈0.01）.结论 QNF对缺血性眩晕大鼠脑损伤有一定的保护作用,能够减轻模型动物的眩晕症状,其脑保护作用机制可能与改善缺血脑组织能量代谢,减少氧化应激和炎性损伤有关.     

Effects of dieldrin on hepatic carbohydrate metabolism in the suckling and adult rat

Hepatic carbohydrate metabolism was studied in adult and suckling rats given age-specific LD50 doses of dieldrin po. These doses in 5-, 10-, and 60-day-old Wistar rats were 38, 28, and 63 mg/kg, respectively. Plasma glucose and free fatty acids (FFA), and hepatic glycogen, phosphoenolpyruvate carboxykinase (PEPCK), fructose-1,6-diphosphatase (FDP), and glucose-6-phosphatase (G6P) were measured 1 and 3 h after administration of the insecticide. Plasma glucose concentrations were elevated (17%) in some 5-day-old rats after 1 h and in all adults after 1 and 3 h (45 and 30%, respectively). Plasma FFA concentrations were decreased (9%) in the 5-day-old rat 1 h after dieldrin. Hepatic glycogen content was reduced in both 5- and 10-day-old pups at 1 hour (22 and 17%, respectively). Hepatic FDP activity was elevated in the 5-day-old rat at 1 h (17%) and was decreased (10%) in the 10-day-old rat at 3 h. Hepatic PEPCK activity was increased in adult animals by 30% 1 h after dieldrin. Furthermore, PEPCK activity was increased at 3 h in rats of all ages (76%, 5-day-old pup; 115%, 10-day-old pup; 56%, 60-day-old adult). Hepatic G6P activity was unaltered by dieldrin. Thus only the activity of hepatic PEPCK is consistently elevated by dieldrin exposure. However, this enhanced PEPCK activity is associated with dieldrin-induced hyperglycemia only in the adult rat.     

Reduction of ethanol-induced gastric damage by sodium cromoglycate and FPL-52694. Role of leukotrienes, prostaglandins, and mast cells in the protective mechanism

The mechanism of action of the "mast cell stabilizers" sodium cromoglycate and FPL-52694 as protective agents against ethanol-induced gastric mucosal damage was investigated in the rat. Using an ex vivo gastric chamber model, various concentrations (10-80 mg/mL) of the two agents were applied to the gastric mucosa prior to exposure to 40% ethanol. Both agents significantly reduced ethanol-induced damage in a dose-dependent manner. When given orally (80 mg/kg) both agents significantly reduced gastric damage induced by subsequent oral administration of absolute ethanol. Pretreatment with indomethacin did not significantly affect the protection afforded by FPL-52694, but did cause a partial reversal of the protective effect of sodium cromoglycate. Changes in gastric leukotriene C4 synthesis did not correlate with the protective effects of the two agents. Both mucosal and connective tissue mast cell numbers were significantly reduced following oral ethanol administration. In the groups pretreated with FPL-52694 or sodium cromoglycate, mucosal mast cell numbers were not significantly different from those in rats not treated with ethanol. Furthermore, the connective tissue mast cell numbers were significantly lower than in ethanol-treated control rats, despite a greater than 95% reduction of ethanol-induced hemorrhagic damage. These results therefore suggest that stimulation of gastric prostaglandin synthesis is not important in the mechanism of action of FPL-52694, and neither agent appears to reduce damage through a mechanism related to effects on gastric leukotriene C4 synthesis. The present studies further suggest that the protection afforded by pretreatment with sodium cromoglycate or FPL-52694 may be unrelated to effects of these agents on the connective tissue mast cell population in the stomach.     

Augmented efficacy of tamoxifen in rat breast tumorigenesis when gavaged along with riboflavin, niacin, and CoQ10: effects on lipid peroxidation and antioxidants in mitochondria

Reactive oxygen species (ROS) play a major role in causing mitochondrial changes linked to cancer and metastasis. Uptake of antioxidants by tissue to reduce the ROS production could be instrumental in controlling cancer. Tamoxifen (TAM), a nonsteroidal anti-estrogen drug most used in the chemotherapy and chemoprevention of breast cancer. Riboflavin, niacin and coenzyme Q10 (CoQ10) are proved to be potent antioxidants and protective agents against many diseases including cancer. The objective of this research is to determine the therapeutic efficacy of combinatorial therapy on mammary carcinoma bearing rats in terms of the mitochondrial lipid peroxidation and antioxidant status especially MnSOD. Female albino rats of Sprague-Dawley strain were selected for the investigation. Mammary carcinoma was induced with 7,12-dimethyl benz(a)anthracene (DMBA: 25 mg), and the treatment was started by the oral administration of TAM (10 mg/kg body weight/day) along with riboflavin (45 mg/kg body weight/day), niacin (100 mg/kg body weight/day) and CoQ10 (40 mg/kg body weight/day) for 28 days. The levels of lipid peroxides, activities of enzymic and non-enzymic antioxidants were measured in the mitochondria isolated from the mammary gland and liver of control and experimental rats. Rats treated with DMBA showed an increase in mitochondrial lipid peroxidation (mammary gland 52.3%; liver 25.1%) accompanied by high malondialdehyde levels along with lowered activities of mitochondrial enzymic antioxidants [superoxide dismutase (mammary gland 19.9%; liver 24.8%), catalase (mammary gland 50%; liver 19.7%), glutathione peroxidase (mammary gland 47.8%; liver 31.1%)] and non-enzymic antioxidants [reduced glutathione (mammary gland 14.3%; liver 13.3%), Vitamin C (mammary gland 6.49%; liver 21.4%) and E (mammary gland 20.3%; liver 22.2%)]. Administration of combinatorial therapy restored lipid peroxide level and the activities of enzymic and non-enzymic antioxidants to near normalcy. In addition, antitumour activity was also found to be enhanced which is evident from the increased expression of tumour suppressor gene MnSOD thereby preventing cancer cell proliferation. These results suggested that TAM treatment is the most effective during co-administration of riboflavin, niacin and CoQ10 in terms of mitochondrial antioxidant and antitumour activity.     

Endotoxin inactivating activity of rat serum

The ability of rat serum to inactivate endotoxin (LPS) was assessed with the aid of the limulus amebocyte lysate assay. Following the addition of various amounts of endotoxin to normal serum the mixture was incubated for 1 hr at 37 degrees C and the residual endotoxin activity determined. One milliliter of rat serum inactivated between 5 and 10 micrograms Escherichia coli LPS per hour. Heating serum for 45 min at 56 degrees C resulted in loss of 80-90% of the LPS inhibitor (LPSI) activity. Serum from cobra venom factor (CVF)-treated rats inactivated between 0.5 and 2.5 micrograms LPS/ml serum. Serum from tolerant rats, even after heating for 45 min at 56 degrees C, inactivates between 10 and 15 micrograms LPS/ml serum/hr; decomplemented tolerant rat serum neutralizes between 5 and 10 micrograms LPS/ml serum/hr. Clearly, the tolerant rat has large quantities of LPSI activity, which does not appear to be complement. The inhibitor found in tolerant rat serum is not species specific since it inactivates Salmonella minnesota and Salmonella typhimurium endotoxins to the same degree and in the same amount as E. coli endotoxin, the agent used to induce tolerance. Both heating serum (56 degrees C) and lead acetate reduce LPSI activity.     

Neutral cytoplasmatic deoxyribonuclease of the rat liver and spleen in carcinogenesis

The activity of cytoplasmic neutral DNA in the liver and spleen of albino rats is studied when the tumour process develops after fast neutrons irradiation, when tumour is induced by 3,4-benzpyrene and after sarcoma 45 transplantation. It is shown that an increase in the enzymic activity with a further decrease during the process development is observed for all studied types of carcinogenesis in the pretumour period. Changes in the activity of natural inhibitor and the enzyme form bound with the inhibitor were not found (except for one or another index in the spleen of animals with sarcoma 45). The enzyme activation in the pretumour period is considered as a tumour defence response of the organism aimed at elimination of damages in DNA which arise as a result of direct or indirect action of carcinogen.     

Metrifonate and dichlorvos: Effects of a single oral administration on cholinesterase activity in rat brain and blood

Cholinesterase activities in rat forebrain, erythrocytes, and plasma were assessed after a single oral administration of metrifonate or dichlorvos. In 3-month-old rats, the dichlorvos (10 mg/kg p.o.)-induced inhibition of cholinesterase reached its peak in brain after 15–45 min and after 10–30 min in erythrocytes and plasma. Cholinesterase activity recovered rapidly after the peak of inhibition, but did not reach control values in brain and erythrocytes within 24 h after drug administration. The recovery of plasma cholinesterase activity, in contrast, was already complete 12 h after dichlorvos treatment. Metrifonate (100 mg/kg p.o.) had qualitatively similar inhibition kinetics as dichlorvos, albeit with a slightly delayed onset. Peak values were attained 45–60 min (brain) and 20–45 min (blood), after drug administration. Apparently complete recovery of cholinesterase activity was noted in both tissues 24 h after treatment. The dose-dependence of drug-induced inhibition of cholinesterase in rat blood and brain was determined at the time of maximal inhibition, i.e., 30 min after dichlorvos treatment and 45 min after metrifonate treatment. The oral ED₅₀ values obtained for dichlorvos were 8 mg/kg for brain and 6 mg/kg for both erythrocyte and plasma cholinesterase. The corresponding oral ED₅₀ values for metrifonate were 10 to 15 times higher, i.e., 90 mg/kg in brain and 80 mg/kg in erythrocytes and plasma. In rats deprived of food for 18 h before drug treatment, the corresponding ED₅₀ values for metrifonate were 60 and 45 mg/kg, respectively, indicating an about two-fold higher sensitivity of fasted rats to metrifonate-induced cholinesterase inhibition compared to non-fasted rats. Compared to 3-month-old rats, 19-month-old rats showed a higher sensitivity towards metrifonate and dichlorvos. At the time of maximal inhibition, there was a strong correlation between the degree of cholinesterase inhibition in brain and blood. These results demonstrate that single oral administration of metrifonate and dichlorvos induces an inhibition of blood and brain cholinesterase in the conscious rat in a dose-dependent and apparently fully reversible manner. While the efficiency of a given dose of inhibitor may vary with the satiety status or age of the animal, the extent of brain ChE inhibition can be estimated from the level of blood ChE activity.     

Study of promutagen biotransformation in the Ames test. IV. The effect of transplanted tumors on the biotransformation of various antineoplastic agents

The effect of transplantation of rat tumours Jensen sarcoma, sarcoma 45, sarcoma M-1, as well as of inoculation of rat normal connective tissue on the processes of biotransformation of antitumour preparations cyclophosphane (CP), thiophosphamide, prospidine and of model compound nitrosomorpholine (NM) was studied. The study was accomplished by means of the Ames test with indicator bacterial strain Salmonella typhimurium TA 1950 in relation to the reactions of the 1st and the 2nd phases of xenobiotics metabolism. It was shown that the presence of tumours leads to inhibition of both metabolic activation processes of the promutagens NM and CP and the conjugation reactions of genetically active metabolites of these compounds with reduced glutathione. Genetic danger is supposed to be increased during application of antitumour preparations, the mutagenic activity of which is due to the activity of their metabolites. It is noted that the most essential effect on biotransformation processes of NM and CP was exhibited by sarcoma M-1, the most important changes of the biotransformation processes of promutagens being observed in the initial period of pathologic process, i.e. on the 3rd day after inoculation. Transplantation of the normal connective tissue of rats had no effect on reactions of both the 1st and the 2nd phase of metabolism of the promutagens studied.     

The Effects of Combined Treatment with Niacin and Chromium on the Renal Tissues of Hyperlipidemic Rats

In this study, 12 months old female Swiss albino rats were used. They were randomly divided into four groups. The animals of group I were fed with pellet chow. Group II were fed with pellet chow and treated with 250 μg/kg CrCl₃.6H₂o and 100 mg/kg niacinfor 45 days. Group III were fed a lipogenic diet consisting of 2% cholesterol, 0.5% cholicacidand 2%sun flower oil added to the pellet chow, andgiven 3%alcoholic water for 60 days. Group IV were fed with the same lipogeni cdiet for 60 day sand treated by gavage technique to rats at a dose of 250 mu/kg CrCl_3.6H₂O and 100 mg/kg niacin for 45 days, 15 days after experimental animals were rendered hyperlipidemic. At the 60th day, renal tissue and blood samples were taken from the animals. The sections were examined under light and electron microscopy. The degenerative changes were much more in the hyperlipidemic rats than the control group. The changes in renal tissue were also observed in hyperlipidemic animals given niacin and chromium. In the hyperlipidemic rats, renal glutathione levels decreased and renal lipid peroxidation levels, and serum urea and creatinine levels were increased. But, renal glutathione levels increased and lipid peroxidation levels and serum urea and creatinine levels decreased in hyperlipidemic rats given niacin and chromium. The purpose of this study was to investigate whether a protective effect of a combination of niacin and chromium is present on the renal tissue of hyperlipidemic rats or not. In conclusion, we can say that niacin and chromium do not have a protective effect on the morphology of the renal tissue of hyperlipidemic rats, except a protective effect on their biochemical parameters.     

The effects of dietary sulfur on selenium utilization by the rat

The antagonistic effects of S on Se utilization were studied by measurement of tissue Se concentrations and glutathione peroxidase (GSHpx, E.C.1.11.1.9) activities in rats offered Torula yeast-based diets supplemented with sodium sulfate to provide 1.5, 3, or 5 g S/kg diet. Increasing sulfur concentrations in the diet caused small but significant decreases in GSHpx activity of liver, spleen, heart, lung small intestine, and skeletal muscle. Also significantly decreased were Se concentrations in liver and hair. Dietary sulfur content had no significant effect on body weight gain of the rats. With an adequate supply of Se in the diet, there are probably no major deleterious effects of dietary S on Se metabolism in the rat.     

Dose-dependent increase of oxidative damage in the testes of rats subjected to acute iron overload

This study describes the in vivo response of rat testes to acute iron overload. Male Wistar rats (250-300 g) were injected ip with iron dextran at doses of 250 (Fe250), 500 (Fe500), or 1000 mg/kg body wt (Fe1000) or with saline (C). Parameters of oxidative stress and iron toxicity were measured 20 h after injection. Total iron content was 3.5-, 5.3-, and 10.4-fold higher in the Fe250, Fe500, and Fe1000 groups, respectively, compared to controls (320 +/- 22 nmol/g tissue). Histological studies showed that: (a) iron accumulated in the sperm and other testes cells, and (b) spermatogenesis was markedly lower in the Fe1000 group. The concentration of alpha-tocopherol, ubiquinol-9, and ubiquinol-10 in the testes was inversely correlated with the extent of oxidation. Testes chemiluminescence was 45% higher in the Fe1000 group compared to controls (41 cps/cm(2)). Endogenous levels of lipid oxidation, evaluated as 2-thiobarbituric acid-reactive substances, were 46, 73, and 82% higher in the groups Fe250, Fe500, and Fe1000, respectively, than in controls (33.6 +/- 1.4 nmol/g tissue). Oxidative damage to DNA evaluated by the presence of 8-oxo-2'-deoxyguanosine (oxo(8)dG), was 26, 39, and 74% higher in the Fe250, Fe500, and Fe1000 groups, respectively, than in the C group (2.3 +/- 0.1 oxo(8)dG/10(5)dG). Protein oxidation was measured as protein thiols and carbonyl content in proteins and glutamine synthase activity. Protein thiols content and glutamine synthase activity were similar in all the groups, while the protein-associated carbonyls content was 96% higher in the Fe1000 group than in the C group (2.1 +/- 0.4 nmol/mg protein). No changes in the activities of superoxide dismutase, catalase, and glutathione peroxidase were observed. The results showed that in vivo iron overload induced oxidative stress and the impairment of spermatogenesis in rat testes that were dependent on the amount of iron supplemented and its accumulation in the tissue.     

The CO2-SFE crude lipid extract and the free fatty acid extract from Perna canaliculus have anti-inflammatory effects on adjuvant-induced arthritis in rats

The anti-inflammatory (AI) activity of a supercritical fluid extract (CO(2)-SFE) of tartaric acid-stabilised Perna canaliculus mussel powder, and of the free fatty acid (FFA) class separated from the CO(2)-SFE extract by column chromatography, was investigated in the rat adjuvant arthritis model. Administration of the CO(2)-SFE extract (100 mg/kg BW/day s.c.) for 15 days post-adjuvant inoculation significantly reduced rear paw swelling by 34% and the deterioration in total body condition by 52% in arthritic rats, compared to vehicle controls. These observations were accompanied by a decreased serum ceruloplasmin oxidase activity, and reduced inflammatory response of the spleen. The mussel FFA extract given at one third of the dose (30 mg/kg BW/day s.c.) and for a shorter treatment period (5 days during the inflammatory phase) achieved an even greater AI activity, and was equipotent to piroxicam (2 mg/kg BW/day s.c.). Preliminary toxicology assessment using both arthritic and non-arthritic (healthy) rats revealed no significant differences between the mussel treatment groups and respective vehicle controls in either organ weights, tissue histology or selected biochemical parameters. These results indicate the CO(2)-SFE crude lipid extract and its FFA components from stabilised P. canaliculus mussel powder contain biologically significant AI activity in vivo, with no apparent adverse side effects.     

Corticotropin-releasing factor: an inhibitor of vascular leakage in rat skeletal muscle and brain cortex after injury

Corticotropin-releasing factor (CRF) and other peptides of the corticoliberin superfamily inhibit development of edema in skin and mucosa after noxious stimuli. Here, the breadth of CRFs protective activity on small blood vessels was examined after injury to skeletal muscle or to brain cortex. Male rats (243 +/- 15 g) were anesthetized with sodium pentobarbital 60 mg/kg i.p. and Monastral blue 60 mg/kg i.v. was injected 3 min before mechanical injury to muscle produced by a 4 cm midline surgical incision in the rectus abdominis or before freeze injury to the cortex produced by applying a cold probe (-50 degrees C) to the skull for 4 min. Vascular leakage, measured as area of dye staining multiplied by its light intensity, was quantified with an image-analysis system. CRF, having the human/rat sequence, 30 micrograms/kg s.c., injected once (30 min) or twice (30 min and 10 min) before injury to muscle or to brain, inhibited the lesion size by 58% and 55%, respectively (tissues taken at 0.5 and 1 h). Microscopy showed that CRF inhibited Monastral blue labeling of small blood vessels. The ED50 (95% C.L.) of CRF for reducing vascular leakage in muscle after celiotomy was 24 (9 to 64) micrograms/kg s.c. h/rCRF injected 30 micrograms/kg s.c. 2 h before celiotomy inhibited vascular leakage after celiotomy in adrenalectomized rats and this effect was not obtained with dexamethasone phosphate, 1 mg/kg s.c. alpha-Helical CRF (9-41), a CRF receptor antagonist, attenuated the actions of CRF on celiotomy. Laser-Doppler flowmeter measurements of skeletal muscle showed that the anti-inflammatory effects of CRF occurred when there were no significant concurrent changes in blood flow. From these results, we surmise that CRF has a versatile protective effect on small blood vessels when it inhibits leakage within different vascular beds.     

Carbon tetrachloride metabolism in partially hepatectomized and sham-operated rats pre-exposed to chlordecone (Kepone)

The potentiation of CCl4 toxicity by pre-exposure to chlordecone (CD) is well established. Chlordecone-induced metabolism of CCl4 and suppressed hepatocellular repair have been offered as possible mechanisms for this potentiation. Recent work using the partially hepatectomized (PH) rat as a model for an actively regenerating liver has provided supportive evidence for the latter hypothesis. The present study was initiated to determine if metabolism and disposition of 14CC14 is altered in the PH rat, and if this is a contributing factor to the reported protective effect afforded by the PH procedure. Male Sprague-Dawley rats (150-175 g) maintained on dietary CD (10 ppm) for 15 days were partially hepatectomized or sham-operated (SH) on day 15. Another group of CD-pretreated rats received 0.9% CoCl2 (60 mg/kg, sc, qd for 2 days) in lieu of the surgical procedure. On day 16 the rats were challenged with a single dose of CCl4 (100 microL/kg, ip) containing 20 muCi 14CCl4. A radiolabel inventory consisting of exhaled 14CCl4, 14CO2 production, total hepatic 14C, free 14CCl4 and covalently bound 14C was taken over a 6-hr time period. Lipid peroxidation and serum enzyme activities [aspartate aminotransferase (AST) and alanine aminotransferase (ALT)] were measured in indices of toxicity. Neither CD pretreatment alone nor CoCl2 treatment alone produced significant alterations in metabolism of low dose (100 microliters/kg) CCl4. No significant difference in 14CCl4 recovery or 14CO2 production was detected for PH versus SH rats. Hepatic 14CCl4-derived 14C (per gram tissue) was greater in PH rats. Values for free 14CCl4, covalently bound 14C, and lipid peroxidation were similar for SH and PH rats.(ABSTRACT TRUNCATED AT 250 WORDS)