d-chiro-Inositol is absorbed but not synthesised in rodents

d-chiro-inositol (DCI) and pinitol (1d-3-O-methyl-chiro-inositol) are distinctive inositols reported to possess insulin-mimetic properties. DCI-containing compounds are abundant in common laboratory animal feed. By GC–MS of 6 m-HCl hydrolysates, Purina Laboratory Rodent Diet 5001 (diet 5001) contained 0·23 % total DCI by weight with most found in the lucerne and soya meal components. In contrast, only traces of l-chiro-inositol were observed. The DCI moiety was present in a water-soluble non-ionic form of which most was shown to be pinitol. To measure the absorption of dietary inositols, rats were fed diet 5001 in a balance study or given purified pinitol or [2H6]DCI. More than 98 % of the total DCI fed to rats as diet 5001, purified pinitol or [2H6]DCI was absorbed from the gastrointestinal tract. Rats chronically on diet 5001 consumed 921 μmol total DCI/kg body weight per d but excreted less than 5·3 % in the stools and urine, suggesting that the bulk was metabolised. The levels of pinitol or DCI in plasma, stools or urine remained relatively stable in mice fed Purina PicoLab® Rodent Diet 20 5053 over a 5-week period, whereas these values declined to very low levels in mice fed a pinitol/DCI-deficient chemically defined diet. To test whether DCI was synthesised or converted from myo-inositol, mice were treated with heavy water or [2H6]myo-inositol. DCI was neither synthesised endogenously from 2H-labelled water nor converted from [2H6]myo-inositol. DCI and pinitol in rodents appear to be derived solely from the diet.

Effects of handling, decapitation, anesthesia, and surgery on plasma noradrenaline levels in the white rat

To determine the normal resting level of plasma noradrenaline (NA) in unanesthetized and undisturbed white rats, 20 warm-acclimated rats previously fed a semisynthetic diet were implanted with an intraaortic cannula and allowed to recover for a period of 5 days. They were then placed in a closed metabolism chamber after fitting an extension to the cannula which allowed blood sampling in animals which were unrestricted and unaware of the procedure. The average NA concentration in the plasma was 0.15 ± 0.01 ng/ml as measured by a radioenzymatic method based on formation of [methyl-3H]adrenaline. Levels of noradrenaline in nanograms per millilitre measured in groups of four to five rats after various treatments were as follows: manipulation, 0.63 ± 0.18; decapitation, 1.32 ± 0.25; 5 min after 3% halothane, 0.23 ± 0.01; decapitation under halothane, 0.40 ± 0.03. In five rats fed Purina laboratory chow at room temperature, values were 0.11 ± 0.02 ng/ml and concentration invariably increased after manipulation and after decapitation. The elevated plasma NA concentration in rats cannulated under halothane anesthesia dropped to normal levels in less than 1 h after recovery from anesthesia, thus indicating that tissue trauma associated with cannula implantation does not have a long-lasting effect on plasma NA levels. These results show that special precautions must be taken to ensure minimal sympathetic activity when resting plasma NA levels are to be measured and that data on the effect of various treatments on peripheral levels of NA based on use of anesthetized, manipulated, or decapitated rats are of doubtful significance as use of these procedures result in abnormally high levels of NA in the control animals used for comparison.

Dietary production and dissolution of cholesterol gallstones in the mouse

Groups of animals fed lithogenic diets were sacrificed at intervals, with serum and bladder bile obtained. Bile was analyzed for bile acids, lecithin, free fatty acids, and cholesterol concentrations, serum for cholesterol and free fatty acids. Gall bladders were also examined for histological change. The chemical response to the diets was a prompt increment in serum and bile cholesterol concentrations. After an initial rise, bile acid content of bile decreased, resulting in a fall in bile acid-to-cholesterol ratios to the point of cholesterol precipitation. Stones once formed dissolved when animals harboring stones were fed Purina laboratory chow. Histological changes appeared in the gall bladder after 2 weeks on the diets and were progressive.

Experimental diabetes mellitus induced by diet in the sand rat

The sand rat ( Psammomys obesus), a rodent from the Near East and North Africa, becomes diabetic when raised on standard laboratory feeds. Animals collected in their natural habitat, on the other hand, show no signs of diabetes mellitus. Twelve animals were raised in the laboratory on Purina laboratory chow supplemented with fresh vegetables. Most of these animals developed severe diabetes mellitus as indicated by hyperglycemia, glucosuria, and pathological lesions including cataracts, obesity, and ß-cell degranulation and vacuolization of the pancreatic islet tissue. Ten animals raised entirely on fresh vegetables remained healthy with no signs of diabetes. Plasma and urine glucose concentrations, body weights, and the occurrence of cataracts are reported.

Influence of diet on utilization of glucose and incorporation of acetate-I-C14 into liver fatty acids and cholesterol in rats

A comparative study of glucose utilization, insulin sensitivity and in vivo incorporation of acetate-C14 into liver fatty acids and cholesterol was conducted in male adult rats. These animals were maintained for 4 weeks on three high carbohydrate diets (glucose, fructose or galactose), a high protein diet (casein), a high fat diet (lard) or Ralston Purina laboratory chow. Glucose utilization was high on the glucose diet and low on the fat diet. Incorporation of C14 into liver fatty acids was very high on the fructose diet, high on the protein and glucose diets, low on chow, and very low on the fat diet. Incorporation of C14 into liver cholesterol was relatively high on chow and relatively low on the fat diet. Glucose utilization in prefasted states and incorporation of acetate into liver fatty acids in fed states were roughly parallel on various diets but no correlation could be noted between glucose utilization and acetate incorporation into liver fatty acids on the one hand and incorporation of acetate into liver cholesterol on the other.

Factors modifying water metabolism in rats fed dry diets

To determine dietary factors which govern water turnover in rats, water intake and output were studied during 24-hour intervals. Rats given water ad libitum and Purina laboratory chow or a synthetic diet voluntarily maintained an antidiuretic state, restricting water intake and excreting urine of nearly maximum concentration. Dietary modifications which have been studied include: addition of large amounts of NaCl or urea; a protein-free diet with or without urea added; and diets containing various levels of Na, K and Cl. Conclusions drawn from these studies are as follows: under most conditions water intake was determined by the minimum urine water for solute excretion or by changes in fecal volume; the degree of antidiuresis maintained by the rats may depend on the electrolyte content of the diet. Nitrogen turnover has an additional influence on water metabolism through the effect of urea excretion on the renal concentrating mechanism. Evidence also presented indicates that Pitressin may act to ‘reset’ the threshold of drinking, with a resulting concentration of body fluids.