Ethanol administration in the drinking fluid to pregnant rats as a model for the fetal alcohol syndrome

Addition of ethanol (ET) to the drinking fluid of pregnant rats has been questioned as an experimental model for the fetal alcohol syndrome (FAS). This model, however, closely simulates human alcohol intake, and in this study we used a modified version of previous protocols to overcome their major defects. A group of female rats was given 10% ET in drinking fluid for one week, 15% for the second week, 20% for the third, and 25% for the fourth, at the end of which they were mated with non-treated males and given 25% ET throughout gestation. Three groups of non-ET treated sex and age-matched rats were studied in parallel: (1) normal controls receiving solid diet ad lib, (2) paired fed rats, and (3) rats fed ad lib the solid diet mixed with 50% fiber. In the ET group, food intake decreased as ET consumption augmented, the ET calories comprising over 30% of the total energy intake during pregnancy. Total energy intake was similar for ET group and normal controls, and was higher than in paired fed animals or those on 50% fiber diet. Body weight gain in ET rats was similar to those on 50% fiber diet, lower than in normal controls and higher than in paired fed animals. At the 21st day of gestation, rats on ET had plasma ethanol levels of 147 +/- 18 mg/dl and higher plasma osmolality than in the other groups studied. In ET rats, fetal body weight was lower than in either normal controls or rats on 50% fiber diet, and fetal body length was shorter than in any other group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lung collagen and elastin after ozone exposure in vitamin B-6-deficient rats

The effects of vitamin B-6 deficiency and ozone exposure on selected features of connective tissue metabolism in lung were investigated in groups of weanling male rats fed one of three diets: B-6-supplemented, fed ad lib; B-6-deficient, fed ad lib; or B-6-supplemented, restricted to the food intake of deficient rats for 5 weeks. Also, perinatal rat pups were studied that were nursed from dams fed one of the 3 diets from parturition to day 15 of lactation. During the final week of each experiment, half of the rats in each of the groups were exposed to 0.64 ppm of ozone (23.5 h per day). The collagen and elastin content, collagen synthesis rate, total protein synthesis rate, and lysyloxidase activity of lungs were measured. Perinatal pups rendered vitamin B-6-deficient were particularly sensitive to ozone exposure (65% died as compared to fewer than 5% of the ad lib or food-restricted controls). When L-proline incorporation into collagen and total protein was investigated using lung minces, food restriction and B-6-deficiency resulted in about one-half the incorporation normally observed. Total lung lysyl oxidase activity was also decreased in B-6-deficient and food-restricted rats compared to B-6-supplemented rats fed ad lib. Exposure to ozone resulted in increased lysyl oxidase activity and collagen synthesis in lungs from B-6-supplemented rats, but such responses were not observed in B-6-deficient or food-restricted (FR) rats exposed to ozone.     

Short-term toxicity study of carnauba wax in rats

Groups of 15 male and 15 female rats were fed diet containing 0 (control), 1, 5 or 10% carnauba wax or 10% cellulose powder for 13 wk and groups of five rats of each sex were given these treatments, except the 1% carnauba wax, for 2 or 6 wk. Rats given 10% carnauba wax or 10% cellulose consumed more food than the controls but showed no differences in body weight, an effect attributed to the dilution of the diet by non-nutrient test materials. The study showed no treatment-related differences in body weights, water intakes, haematological values, serum-enzyme activities, urinary concentration and 'dilution' tests, organ weights or histological findings. The no-untoward-effect level for carnauba wax in the diet was 10%, which represented a mean intake of approximately 8.8 and 10.2 g/kg body weight/day in males and females, respectively.     

The effect of chronic underfeeding on organ weights of rats How to interpret organ weight changes in cases of marked growth retardation in toxicity tests?

Growing male rats were kept on a restricted feed intake. After 13 weeks they reached a final body weight of 250 g in comparison with 366 g of their ad lib. fed controls.The relative weights of the heart, kidneys, spleen, pituitary and prostate/ seminal vesicle were not altered by underfeeding. The relative weights of the brain, adrenals and testes were increased by 30 to 40% in the feed-restricted groups, the thyroid by about 20%. The relative weight of the liver was decreased by about 30%.When growth is markedly reduced in a toxicity experiment alterations of this kind in the organ weight: body weight ratios have to be expected as a physiological response of the organism to decreased feed intake. They must be differentiated from organ weight changes resulting from primary toxic influences of the drug tested.     

Effects of body weight on taste of male and female rats

Single-choice taste (solution and mixed-diet) tests revealed that ad lib fed male rats with increasing body weight showed increased intake on sweet taste as compared to intake of identically aged ad lib fed female rats with static body weight. On meal-time (3 hr) and meal-size (50% diet) restrictions though rats of either sex increased on intake of sweet taste, the increment shown by female was higher and it was correlated with their greater % loss in bw. Hence it appears that the basis for sweet taste preference is the mismatch between actual and target body weight irrespective of sex of animal.     

Estrous cyclicity in rats fed an ethanol diet for four months

This study is designed for better understanding the effect of chronic ethanol treatment on ovarian function in sexually mature rats by assessing the estrous cycle. Rats were fed the following diets for 17 weeks: a liquid diet containing 5% (w/v) ethanol, a liquid diet without ethanol (pair-fed) or laboratory chow and water ad lib. Estrous cycles were determined throughout the 17 weeks and the rats were necropsied at proestrus and metestrus. Ethanol-fed rats had significantly more irregular estrous cycles than did controls, and the duration of an estrous cycle in the ethanol-treated rats was statistically longer than that of controls. However, ovarian and uterine weights and ovarian and vaginal morphology of ethanol-fed rats were similar to those of controls.     

Effects of undernutrition on transit time and body weight of rats.

Rats given 50% and 25% of their ad lib food intake were taken as undernourished, while those on ad lib intake served as controls. Water was given ad lib for all rats. Body weight of all rats was measured daily. It showed decrease in undernourished groups but not to the extent expected from calorie intake. Fifty tiny (1-2 mm) orange coloured plastic markers mixed with food were given to all rats, at 11.00 p.m., and were collected from faeces at regular intervals of 1 h each till 80% of markers were obtained. Period (hrs) for collection of 80% markers was taken as total transit time. It showed increase with increased undernutrition (ad lib 38.9 +/- 2.1 hrs, 50% cal 68.2 +/- 5.3 hrs, 25% cal 105.00 +/- 3.3 hrs). Delayed transit time in the undernourished by prolonging contact period between food and absorptive surface of intestine probably caused increase in absorption of nutrients and thus counteracted against the loss in body weight of underfed rats.     

Ozone exposure, food restriction and protein deficiency: changes in collagen and elastin in rodent lung

Two groups of weanling or young adult rats were fed ad lib casein-based diets containing 4 or 16% protein. Food was restricted in a third group (fed the 16% protein diet) to the amount consumed daily by rats (adult or weanlings) fed the 4% diet. After 3 weeks (weanlings) or 1, 3 or 5 weeks (adults), one-half of the rats in each group were exposed to 0.64 ppm (1.28 mg/m3) of ozone for 7 days (23.5 h each day). Several parameters were then evaluated related to lung connective tissue metabolism including: (1) total lung hydroxyproline, (2) total lung elastin, (3) apparent rates for lung collagen synthesis and elastin accumulation and (4) lung and body weights. In general, the response to protein deficiency and food restriction was more pronounced than to ozone exposure. Protein deficiency and food restriction resulted in decreased lung size and collagen content. However, the ability of lung to respond to ozone (in relative terms) was not altered by changes in diet as assessed by changes in lung weight or the collagen synthetic rate.     

Chronic ethanol intake modifies estrous cyclicity and alters prolactin and LH levels

The effect on the estrous cycle, as well as prolactin, luteinizing hormone (LH) and alcohol levels, were studied in female rats during chronic alcohol intake. Rats were fed the following diets for 5 weeks: a liquid ethanol diet (5% ethanol, w/v), an isocaloric liquid diet (pair-fed) or laboratory rat-chow and water ad lib. Ethanol-fed rats showed an irregular estrous cycle with a significant decrease in the frequency of the estrus + proestrus phases, and an increase in the duration of the diestrus + metaestrus phases, when compared with both the pair-fed and rat-chow groups. In these alcoholic rats, the estrous cycle phase was correlated with blood alcohol levels, which were found to be lower in the estrus + proestrus than in the other phases of the cycle. At the same time plasma prolactin levels were higher and plasma LH levels lower in the alcoholic rats than in either control group. These data indicate that chronic ethanol consumption prolongs the diestrus phase together with altered plasma prolactin and LH levels in female rats.     

The effects of diet, ad Libitum feeding, and moderate and severe dietary restriction on body weight, survival, clinical pathology parameters, and cause of death in control Sprague-Dawley rats.

A 2-year study was conducted in Sprague-Dawley rats to compare the effects of ad libitum (AL) feeding and dietary restriction (DR) on body weight, survival, cause of death, and clinical pathology parameters. Three groups of 120 rats/sex each received the following daily rations of a maintenance rodent diet: ad libitum (AL group); 75% of adult AL food consumption (25% DR group); and 45% of adult AL food consumption (55% DR group). Among the 3 groups, there were generally no differences in relative (food intake per gram of body weight) food consumption. Compared to the AL group, decreased body weight gain occurred in DR groups and was associated with an increase in survival proportional to the DR rate. The main cause of death was pituitary adenomas in all groups. Decreases in total leukocyte, segmented neutrophil, lymphocyte, and platelet counts occurred in the 55% DR group. In serum biochemistry, there were decreases in total protein, albumin, total and HDL cholesterol, and total calcium, and increases in alkaline phosphatase activities and chloride in 55% DR females, as well as decreases in triglycerides in the 55% DR group and in 25% DR females. Results of urinalyses showed decreases in urine volume and protein, and increases in urinary pH in both DR groups. In conclusion, a DR rate of approximately 25% appears to be appropriate for Sprague-Dawley rats in toxicity and carcinogenicity assays to improve survival without impairing growth and routine clinical pathology parameters.     

Testicular effects of cyclohexylamine hydrochloride in the rat

Testicular effects of cyclohexylamine hydrochloride (CHA) were investigated in Wistar and Sprague-Dawley rats. Groups of 25 rats were fed diets containing 6000, 2000 and 600 ppm CHA for 90 days and in addition ad lib., pair-fed and paired-weight control groups were used to assess the role of reduced food intake in the development of testicular lesions.Rats fed diets containing 6000 and 2000 ppm CHA showed significant decreases in food consumption, body weight and body weight gain. However, significant increases in the incidence of testicular lesions were found only in those animals fed 6000 ppm CHA. Absence of a similar incidence of lesions in either the paired-weight of pair-fed control groups indicated that inanition was not primarily responsible for the development of the lesions. The toxicological significance of these findings is discussed.     

Lack of chronic toxicity or carcinogenicity of dietary N-acetylglucosamine in F344 rats

Chronic toxicity and carcinogenicity of N-acetylglucosamine (GlcNAc) were examined in male and female F344 rats. GlcNAc was given in the diet at levels of 0%, 1.25%, 2.5% or 5% to groups of 10 rats of each sex for 52 weeks in the chronic toxicity study and 0%, 2.5% or 5% to groups of 50 rats of each sex for 104 weeks in the carcinogenicity study. GlcNAc exerted no toxic effects with regard to clinical signs, mortality, hematology, serum biochemistry and histopathological assessment. Slight suppression of body weight gain was observed at more than 2.5%, but this appeared to be due to slight reduction of caloric intake with the high concentration of test compound, rather than any toxicity. Thus, it was concluded that GlcNAc has neither toxic nor carcinogenic effects in F344 rats, the no observed adverse effect levels (NOAEL) estimated from the chronic toxicity study being 5% in both sexes, equivalent to 2323 and 2545 mg/kg/day in males and females, respectively.     

Toxicity and carcinogenicity studies of Caramel Colour IV in F344 rats and B6C3F1 mice.

Caramel Colour IV, a type of caramel colour used in the manufacture of cola soft drinks, was evaluated for subchronic and chronic toxicity in rats, and carcinogenicity in Fischer-344 (F344) rats and B6C3F1 mice. In each of the studies, Caramel Colour IV was mixed with demineralized water and the solutions given to the animals ad lib. in the drinking fluid. The concentrations of Caramel Colour IV in the drinking fluid were adjusted periodically to achieve the desired caramel colour intake per kg body weight. In the range-finding studies, groups of 30 rats/sex were given Caramel Colour IV at levels of 0, 15, 20, 25 or 30 g/kg for 13 wk, and groups of 10 male rats were given levels of 0, 2.5, 5, 10 or 15 g/kg for 6 wk followed, for some dose groups, by a 2-wk withdrawal period, and then re-initiation of dosing for another 2 wk. In the rat chronic toxicity study, levels of Caramel Colour IV of 0, 2.5, 5, 7.5 or 10 g/kg were given to groups of 25 rats/sex for 12 months. The test groups in the rat and mouse carcinogenicity studies were composed of 50 animals/sex and each species was given the caramel colour at levels of 0, 0, 2.5, 5 or 10 g/kg for 24 months. In each of the studies, treated animals tended to have dose-related lower water consumption than controls. This was attributed to poor palatability of the drinking fluid, and was generally associated with decreased food consumption and body weights. Rats given caramel colour often had soft or liquid malodorous faeces although there were no treatment-related ante-mortem observations in mice. Blood biochemical changes in the rat (i.e. reduced blood urea nitrogen, alkaline phosphatase and total serum protein) appeared to be related to dietary influences and were not considered toxicologically significant. There were no treatment-related alterations in haematological variables or treatment-related differences in survival or in the incidence of benign or malignant tumours among treated and control groups and no toxicologically important pathological findings. On the basis of these studies, Caramel Colour IV was not toxic or carcinogenic in F344 rats or B6C3F1 mice. The highest dose level tested in the long-term studies (10 g/kg) was considered to be the no-observed-adverse-effect level (NOAEL).     

Effect of schedule feeding on water intake and urine output in rats

Water intake of schedule feeding rats was correlated to food intake through variations in calorie content of food. On intake time restriction (3 h) schedule, it was positively correlated while on amount restriction schedule (25% and 15% food) correlation was negative. Water-to-food ratio (W/F) of 3 hFW rats was decreased whereas W/F of 25% and 15% food animals, it was increased as compared to ad lib W/F. On calorically rich (3.2 cal/gr) diet 3 hFW rats food intake (7.8 +/- 0.6 gr) and water intake (4.7 +/- 0.3 ml) remained unaltered, while ad lib rats food intake (14.7 +/- 0.9) was decreased and water intake (16.2 +/- 1.1) increased as compared to their intake on calorically poor (2.8 cal/gr) diet. Urine percent over water intake (u/w x 100) was inversely related to food intake of rats (on ad lib food, 13.8%; on 25% food 29.1% on 15% food 31.8%) excepting for urine percent of 3 hFW rats which was (7.6%) disproportionately decreased.     

Chronic methylxanthine treatment in rats: A comparison of Wistar and Fischer 344 strains

Caffeine, theophylline or aminophylline were administered chronically to rats of both sexes, in the weight range 30–245 g. Self-injurious behaviour was noted only rarely in Wistar rats allowed free access to food, but developed over 3 to 4 weeks in half of the animals given a restricted diet of about one third of the intake of control rats. Fischer rats showed self-injurious behaviour more readily, 87% of animals showing signs within 9 days even on an ad lib diet. It is suggested that Fischer rats treated with methylxanthines may provide a model of the Lesch-Nyhan syndrome. Behavioural observations made during the period of methylxanthine treatment suggest than an activation of both the dopamine and 5-hydroxytryptamine neurone systems may be produced. Further work will seek a relationship between these systems and self-injurious behaviour.     

Subchronic toxicity study of Caramel Colour II in F344 rats.

Caramel Colour II is a distinct type of colourant with a pronounced reddish hue. It is made with sulphite reactants but without ammonia. The red colour and a high alcohol solubility provide functional characteristics that are important in foods or beverages containing natural flavour extractives. Caramel Colour II is widely used in ice creams and liqueurs; however, it represents less than 1% of total caramel colour manufacture. The toxicity of Caramel Colour II was evaluated in a 13-wk study in Fischer-344 (F344) rats. The test material was mixed with demineralized water and the solutions were given to the animals ad lib. in the drinking fluid. The concentrations of caramel colour in the drinking fluid were adjusted periodically to achieve the desired caramel colour intake/kg body weight/day. Groups of 20 rats/sex were given Caramel Colour II at levels of 0, 4, 8, 12 or 16 g/kg for at least 13 wk. There were no deaths in any of the groups fed Caramel Colour II. All rats fed caramel colour had soft faeces. All treated groups also had lower fluid consumption that was attributed to poor palatability of the high concentrations of caramel colour that were fed. A number of changes observed (reduced food consumption in all treatment groups except males given 4 g/kg; significantly lower body weights for males given 12 g/kg or more and for females given 8 g/kg or more; lower urine volume and higher specific gravity) were attributed to the reduced water intake and not considered to be toxicologically significant. There were no consistent treatment-related alterations in haematology or blood chemistry variables, and random changes noted were not associated with macroscopic or microscopic pathological alterations. There were no toxicologically important pathological findings. Based on this study, Caramel Colour II was not toxic in F344 rats treated for 13 wk. The highest dose level tested in this study (16 g/kg) was considered to be the no-observed-adverse-effect level.     

Effect of sodium saccharin and calcium saccharin on urinary parameters in rats fed Prolab 3200 or AIN-76 diet

The effects of the salt form of saccharin and of diet on urinary ion levels have been studied in rats. Sodium saccharin (NaS) or calcium saccharin (CaS) was fed at a level of 5% in either Agway Prolab 3200 diet or AIN-76 diet to male, 5-wk-old F344 rats for 10 wk. The AIN-76 diet contained considerably less calcium, sodium and potassium than the Prolab 3200 diet, and smaller amounts of these ions were eliminated over 24 hr in the urine of rats fed the AIN-76 diet. Although food consumption was less in the groups fed AIN-76, total urinary saccharinate ion excretion with either saccharin salt was comparable with, or even higher than, that excreted by rats fed either salt in the Prolab 3200 diet. Rats fed Prolab 3200 eliminated approximately equal amounts of saccharinate ion in the faeces and urine. Rats fed AIN-76 eliminated about 10-20 times as much saccharin in the urine as in the faeces. Total saccharin excretion (faecal and urinary) was not influenced by the salt form. Water intake and urine volume were lower in rats fed control AIN-76 diet in comparison with those fed Prolab 3200, and were increased above the control level in groups fed saccharin in the AIN-76 diet. Urine electrolyte levels and osmolality were lower in the groups fed AIN-76. In general, NaS administration in either diet resulted in increased urinary sodium compared with controls, and the pH was at, or above, the level of control rats. CaS resulted in increased urinary calcium and decreased pH. There were marked diurnal variations in the urinary excretion of the various electrolytes, pH, and urine volume over a 24-hr period in all rats. This diurnal variation was more pronounced in the rats fed the Prolab 3200 diet. These results indicate that NaS and CaS have marked effects on the excretion of urinary electrolytes, and that these effects are influenced by diet.     

Behavioural changes on diet selection and serotonin (5-HT) turnover in rats under pizotifen treatment.

The effects of pizotifen on protein and carbohydrate self-selection in rats over a seven-day period, and on 5-HT turnover was studied. Four groups of male Wistar rats were individually caged and ad lib fed with a standard (SD) and (50%) carbohydrate-enriched diet (CED), sweet (diet group I) or not (diet group II). Food intake was measured daily 4 hr after IP injection of pizotifen (2.5 mg/kg) or vehicle. 5-HT and 5-HIAA in the hypothalamus (Hy), striatum (St) and hippocampus (Hi) were assayed on the 8th day of the experiment. Pizotifen increased the consumption of SD. The absolute intake of CED remained totally and daily unchanged, while the percentage proportion was reduced. Total food intake was increased by the drug which seemed to affect the proportion rather than the absolute amounts of carbohydrate and protein consumed. This effect was independent of the carbohydrate taste. There was a decrease of 5-HT levels in the Hi, while 5-HIAA/5-HT ratio was increased in the Hy and in the Hi of animals that consumed sweet carbohydrate. The above data suggest a role of pizotifen on 5-HT central metabolism and diet selection and support the view that changes of 5-HT metabolism in the Hy and Hi are responsible for protein selection and the regulation of SD/CED ratio, but they cannot explain drug's effect on total food intake.     

A chronic toxicity study of cyadox in Wistar rats

To investigate the chronic toxicity of cyadox, a growth promoting agent, five groups of Wistar rats (30 rats/group/sex) were fed with the diets containing cyadox (0, 100, 400 and 2000 mg/kg) or olaquindox (400 mg/kg) for 78weeks. There were significant decreases in body weights in both genders during most of the study period in 2000 mg/kg cyadox and 400 mg/kg olaquindox rats. Significant decreases in serum alkaline aminotransferase in the 2000 mg/kg cyadox rats at weeks 26, 52 and 78 were observed. Relative weights of liver and kidney were significantly increased in 2000 mg/kg cyadox and 400 mg/kg olaquindox rats at weeks 26, 52 and 78. A significant increase in relative brain and heart weights in 2000 mg/kg cyadox males was observed. The histopathological examinations revealed that 2000 mg/kg cyadox diet or 400 mg/kg olaquindox diet could induce proliferation of bile canaliculi in the portal area of liver and swelling and fatty degeneration of the proximal renal tubular epithelial cells in kidneys. In conclusion, the target organs of cyadox for rats were liver and kidney. The no-observed-adverse-effect level of cyadox in this study was estimated to be 400 mg/kg diet.