Food and water intake, growth, and adiposity of Sprague-Dawley rats with diet board for 24 months.

Ad libitum (AL) feeding of rats leads to obesity and increased result variability, as well as premature morbidity and mortality. It may also alter metabolism and responses to foreign compounds. Moderate dietary restriction (DR) reduces these untoward effects without compromising the sensitivity of rodent bioassays. The diet board (DB) is a novel method for achieving moderate DR in group housing. Food pellets are firmly attached into grooves in an aspen board, and rats have to gnaw the wood in order to eat. Food is available continuously, but due to the effort involved rats eat less. This study simulated a chronic safety test to assess the long-term effects of DB feeding. A total of 146 male and female outbred Sprague-Dawley rats, nine weeks old at onset, were housed in groups of three and fed either AL or with DBs for two years. Food and water consumption were measured at six time points. The rats were weighed every one to two weeks. Body and tibial lengths and epididymal fat weight were measured at necropsy. Modified body mass index was calculated at five time points after one year of age. DB feeding reduced body weight and fat tissue moderately, more so in males. DB males ate less than AL males, but no differences were seen in the total food consumption in the females. There was no consistent difference in the within-group variations of the measured parameters. DB is a workable DR method, albeit some modification could enhance and standardize its DR effects, especially in female rats.

Heat shock protein 60 autoimmunity and early lipid lesions in cholesterol-fed C57BL/6JBom mice during Chlamydia pneumoniae infection.

Chronic Chlamydia pneumoniae infection and autoimmunity to heat shock protein 60 (Hsp60) have both been documented to be associated with atherosclerosis. Herein, we studied the effects of C. pneumoniae infection and a diet with a low-cholesterol supplement on the development of autoantibodies to mouse Hsp60 and early lipid lesions in the aortic valve of C57BL/6JBom mice. In addition, pulmonary infection was investigated. C57BL/6JBom mice were given one to three C. pneumoniae inoculations and fed either a regular diet or a diet enriched with 0.2% cholesterol. Autoantibody responses against mouse Hsp60 developed in both diet groups when the mice were infected with C. pneumoniae and in uninfected mice fed a cholesterol-enriched diet. C. pneumoniae infections increased subendothelial foam cell accumulation in mice on a 0.2% cholesterol-enriched diet (p = 0.022), without apparent hypercholesterolemia. These in vivo data suggest that autoantibodies against mouse Hsp60 develop as a consequence of cholesterol feeding and repeated C. pneumoniae infections. Further, infectious burden increased early lipid lesions in C57BL/6JBom mice fed a cholesterol-enriched diet.

Different toxicological profile of two COMT inhibitors in vivo: the role of uncoupling effects.

The toxicity profiles of entacapone and tolcapone, novel catechol- O-methyl-transferase (COMT) inhibitors, have been reported to differ from each other. It has also been shown that tolcapone, but not entacapone, is a potent uncoupler of oxidative phosphorylation in vitroat low micromolar concentrations. Signs of hepatotoxicity induced by tolcapone treatment have been previously reported in toxicological studies and in clinical use. The present study was designed to investigate the mechanism of hepatotoxicity of tolcapone and its possible relationship to uncoupling of oxidative phosphorylation in vivo. A 15-day oral toxicity study with entacapone or tolcapone (300 and 500 mg/kg/day) was carried out, and 2, 4-dinitrophenol (DNP), a known uncoupling agent of oxidative phosphorylation, served as a positive reference substance (20 mg/kg/day). No treatment related findings were observed in entacapone-treated rats. Clinical chemistry parameters regarding hepatocellular damage were increased in tolcapone and DNP-treated animals. The energy status measured as ATP/ADP ratio from the liver samples and energy charge (EC) in liver cell mitochondria were diminished both in tolcapone- and in DNP-treated rats. These signs together with clinical symptoms consisting of increased respiration, decreased activity and drowsiness, and elevation of the rectal body temperature observed in tolcapone- and DNP-treated animals suggest a relationship between the treatment and uncoupling of oxidative phosphorylation in vivo.

Comparative toxicological study on the hepatic safety of entacapone and tolcapone in the rat.

Entacapone and tolcapone are novel COMT (catechol-O-methyltransferase) inhibitors indicated for the adjunctive treatment of Parkinson's disease (PD) in combination with levodopa. The marketing authorisation of tolcapone was suspended in the European Union (EU) in 1998 mainly due to severe abnormal hepatic reactions. This fact raised concern about the safety of COMT inhibitors in the treatment of parkinsonian patients. In order to investigate whether these COMT inhibitors exhibit different effects on the liver comparative toxicological studies were performed in the rat. Short term toxicological studies in rats at high oral doses of entacapone and tolcapone (200, 400 or 600mg/kg daily) were carried out. Tolcapone (400 mg/kg/day or 600 mg/kg/day) increased mortality after only one week treatment and induced signs of toxicity such as a rise in body temperature, stimulation of respiration and rapid onset of rigor mortis after death. Entacapone did not show any adverse effects at the tested dose levels. In the histopathological examination liver cell necrosis was observed in the tolcapone (400 and 600mg/kg/day) treated rats, but it revealed no treatment related signs of toxicity in entacapone-treated rats. We conclude that the toxicological profile of the two COMT inhibitors, entacapone and tolcapone, differ from each other, tolcapone--unlike entacapone--showed hepatotoxicity.

Studies on the contact sensitizing activity of dithranol (anthralin) and 10-butyryl dithranol (butantrone).

The contact sensitizing activity of dithranol and butantrone (10-butyryl dithranol) was studied in 3 animal models: the guinea pig maximization test (GPMT), the closed patch test (CPT), and the mouse ear swelling test (MEST) in 2 different mouse strains. In the GPMT, both dithranol and, to a greater extent, butantrone showed sensitizing potential. Because butantrone was less irritant, the concentrations used were 10x higher than those of dithranol. In the CPT, only butantrone was slightly positive. In the MEST, with both CF-1 and Balb/c mice, dithranol caused less swelling of the test ear after challenge than butantrone. According to the evaluation criteria of the MEST, only butantrone caused sensitization in 50% of the CF-1 mice and in 40% of the Balb/c mice. Thus, the GPMT was the only test which indicated the minor contact sensitizing potential of dithranol. On the other hand, the 10-butyryl analogue of dithranol showed undoubtedly stronger contact sensitizing potential than the parent compound in all tests. Therefore, as compared to dithranol, an increased risk of sensitization should be considered.

Skin irritation by dithranol (anthralin) and its 10-acyl analogues in 3 animal models.

The skin irritant properties of a single application of dithranol (anthralin), a typical "delayed irritant", and its 10-acyl analogues in acetone or white petrolatum were compared in 3 animals models. Maximal irritation was reached at about 24 h in mouse ear, 48 h in guinea pig back and 1 week in miniature swine back, the last-mentioned serving as a good model of human skin. In all animal species, butantrone was significantly less irritant than dithranol, 10-acetyl dithranol or 10-propionyl dithranol. 10-acetyl dithranol was the most irritant compound. Clinical trials with butantrone on psoriasis are justified.