Growth and longevity of Wistar rats receiving a diet whose protein content is rapidly lowered in relation to aging]

Growth and longevity of the Rats were the same when: (i) the diet was rich in casein (21%), from weaning to death: (ii) the casein content of this diet (without B12) was progressively lowered from weaning to 200 days of age, and thereafter was 7%. When the casein level had been too rapidly lowered, inducing retardation of growth after 75 days, maximal growth was lowered and life span was increased.     

Lack of influence of vitamin D deficiency on insulin release from the isolated pancreatic islets of rats

Pancreatic islets were isolated from young (100 g) and adult (390 g), normal and vitamin D deficient male Sprague-Dawley rats. The release of insulin from leucine-stimulated or glucose-stimulated islet was not altered by vitamin D deficiency. The in vitro addition of either 25-hydroxy- or 1,25-dihydroxyvitamin-D had no effect on insulin release from either normal or vitamin D deficient islets. We conclude that the earlier report (Normal et al., Science 209 (1980) 823-825) on vitamin D deficiency depressing insulin secretion from the perfused pancreas must be related to the vitamin's effect on insulin synthesis and not the islet's release of insulin.     

Reproductive consequences of mega vitamin E supplements in female rats

Summary Female rats fed 0, 25, 2500 and 10,000 IU vitamin E/kg diet for 3 months were examined for reproductive performance. On 10,000 IU vitamin E/kg diet, the fertility of inseminated rats was significantly reduced as compared to rats given normal or nutritional levels of vitamin E.This work was supported by research grants from the National Research Council of Canada and the Research Committee of The University of British Columbia. We thank Mrs Virginia Green for her help in statistical analysis. Reprint requests should be addressed to Dr I. D. Desai, Professor of Nutrition.     

Maternal behavior in two rat lines selected for differences in the acquisition of two-way avoidance

Summary The maternal behavior of Roman high- and low-avoidance (RHA/Verh and RLA/Verh) rats was studied, using a time-sampling method. It was concluded that: a) RLA/Verh mothers spent more time with their young, b) RHA/Verh mothers were more active, and c) the mothers of both lines mostly blanketed their young during nursing, although the RHA/Verh mothers assumed the side-nursing position more often than their counterparts.This work was partly supported by a research grant from the Swiss Association of Cigarette Manufacturers. Reprint reqyests should be addressed to P. Driscoll at the given address.     

Effect of a restricted diet on the in vitro glucose-induced insulin release of aging rats

To study the effect of a sudden loss of body weight on the -cell function of aging rats, basal and glucose-induced insulin secretion was measured in pancreatic islets obtained from young (2-month-old), adult (12-month-old) and aging (24-month-old) rats, either fed ad libitum or fed a restricted diet (50% caloric restriction). Basal insulin secretion was similar in islets of young, adult and older rats. Glucose stimulated insulin release was significantly reduced in aging rats as compared to young animals. Animals fed a restricted diet showed a prolonged and higher secretory rate during first phase release when compared to animals fed ad libitum.     

A synergistic interaction between the teratogenic effect of trypan blue and dietary deficiency in the rat.

There was an increased incidence, compared to controls, of exencephaly and microphthalmia in the offspring of rats fed a vitamin D deficient diet and injected with trypan blue on day 9 of gestation. Oral vitamin D did not reverse the effect.     

Influence of dietary lactose on the development of lactase activity in the digestive tract of the pig]

Lactase activity has been measured in the pancreas, the small and large intestine of 79 pigs varying in age from 6-7 months. The endogenous enzyme level fluctuated along the small intestine but the activity did not vary according to the level of lactose fed in the diet either just after weaning or from 25 to 100 kg of live weight. Measurements performed in the content of the intestine showed that lactose could be digested by the enzymes of the microflora mostly active in the ileum, the caecum and the large intestine.     

Photoperiodic induction of diapause in an insect is vitamin A dependent

Summary A photoperiodic response was found to be absent in larvae of the parasitoid waspApanteles glomeratus when its host (caterpillars ofPieris brassicae) was reared on a low-carotenoid artificial diet. Addition of vitamin A to the host's diet restored the response to short-day photoperiods in the wasp larvae, thus showing that vitamin A is essential for photoperiodic induction of diapause. Possibly vitamin A or a derivative of vitamin A functions as the photoreceptor pigment for the photoperiodic reaction in this species of insect.     

Joint effects of dietary protein levels and vitamin A additions on the induction of cytochrome P450 by DDT in rats]

A 5 P. 100 level of protein from casein in a diet does not allow vitamin A to modify significantly induction of cytochrome P 450 on the Rat receiving or not receiving DDT. When the protein increases to a 15 p. 100 level, the induction is better providing vitamin A is to be given. If protein and vitamin A are necessary for cytochrom P 450 induction, an increase of protein level remains inefficient without vitamin A.     

The effect of dietary fibre on85Sr and47Ca absorption in infant rats

Summary The retention of bone-seeking radioisotopes⁸⁵Sr and⁴⁷Ca was about 20% lower in the femur of 6-day-old infant rats artificially fed on milk, milk supplemented with calcium and phosphorus, and milk supplemented with strontium when 6% cellulose type dietary fibre was added to the diet.Acknowledgments. This work was supported by a research grant from the Scientific Research Council of the Socialist Republic of Croatia. The authors wish to thank Mrs M. Buben, E. Herak, and K. Pribi for their technical assistance.     

A synergistic interation between the teratogenic effect of trypan blue and dietary deficiency in the rat

Summary There was a increased incidence, compared to controls, of exencephaly and micropthalmia in the offspring of rats fed a vitamin D deficient diet and injected with trypan blue on day 9 of gestation. Oral vitamin D did not reverse the effect.Acknowledgments. The author wishes to thank Dr G. Lumb and Dr. B. Mawer for advice on diets, and Mrs de Silva for making the assays.     

Plasma and hepatic antioxidant control and vitamin A nutritional status

Twenty-seven rats were divided into three groups and fed on diets containing 0.3, 6 or 60 RE (retinol equivalent) retinyl palmitate/g food. After 7 weeks, hepatic vitamin A uptake was found to be more efficient in vitamin A-deficient rats than in rats given adequate vitamin A. We showed that during the metabolic adaptation of the animals to the level of vitamin A in the diet, extensive modifications occur in the antioxidant defences of the organism. In parallel with the increase in the level of vitamin A, the decrease in the level of -tocopherol in the plasma can bring about a greater susceptibility of the lipoproteins to oxidative stress. Similarly, the decrease in the hepatic -tocopherol level and in glutathione peroxidase activity leads to the weakening of the liver's antioxidant defences.     

Action inhibitrice du thiouracil sur la carotine

Summary White rats submitted to a purified diet without vitamin A develop normally with carotene. When these animals are treated with thiouracil they show trophic alterations analogous to these observed in animals submitted to a diet without vitamine or provitamine A. These disturbances are cured immediately when vitamine A or powdered thyroids are given; on the other hand they continue when the dose of carotene is augmented. Iodine too exercises a protective and curative effect with an antagonistic action to thiouracil.The authors interpret these disturbances as due to an inhibition of the carotinase produced by thiouracil.     

Wirkungen von Gallensäure und Vitamin D auf die Kalziumresorption bei der Ratte

Summary Comparison of the effects of vitamin D and the bile salt Taurochenodeoxycholate on calcium absorption in young rats suggests that bile salt enhancement of calcium absorption occurs mainly in the ileum in normal animals but occurs in both duodenum and ileum in rachitic rats. Also suggested is that bile salts mainly assist the entry of calcium into mucosal cells from the gut lumen while vitamin D chiefly aids the egress of calcium from the cells into the extracellular fluid.     

Latent iron deficiency alters gamma-aminobutyric acid and glutamate metabolism in rat brain

A diet containing 18-20 mg iron/kg to young weaned rats for 8 weeks altered the metabolism of gamma-aminobutyric acid and glutamate in the central nervous system without affecting blood hemoglobin. Subsequent rehabilitation with 390 mg iron/kg diet for 2 weeks normalized these changes.     

Induction of epidermal cell proliferation by a tumour promoter in vitamin B6-deficient mice

Summary Topical application of the tumour promoter 12-0-tetradecanoyl-phorbol-13-acetate to skin caused a marked enhancement of mitotic acitivity both in mice maintained on a complete diet or on a vitamin B₆-deficient diet.Acknowledgment. The author thanks Mr P. Daenke for excellent technical assistance.This investigation was supported by the Australian Research Grants Committee and the Australian Tobacco Research Foundation.     

Dietary vitamin E does not protect from endotoxin-induced hepatic microvascular dysfunction

Starting from the concept that lipopolysaccharide (LPS)-associated hepatotoxicity involves the action of reactive oxygen species, the present study was conducted to test whether vitamin E, a lipophilic antioxidant, prevents LPS-induced hepatic microvascular dysfunction and liver injury. Fifty-two rats were divided into three groups and fed diets containing 0 (n=16), 75 (n=18) or 8000 mg (n=18) α-tocopherol acetate/kg food for four weeks. At 1 h and 6 h after intravenous LPS-exposure (10 mg/kg E. coli LPS) hepatic microvascular response and liver injury were assessed by the analysis of Kupffer cell phagocytic activity, leukocyte-endothelial cell interaction and nutritive sinusoidal perfusion (intravital fluorescence epi- illumination technique) as well as bile flow, serum liver enzyme activities and tissue histomorphology. In animals fed with 75 mg vitamin E/kg (standard diet), LPS caused hepatic Kupffer cell activation (increased phagocytic activity) and hepatic microvascular leukocyte activation, with stasis in sinusoids and adherence in postsinusoidal venules (1 h) followed by leukocytic infiltration into tissue (6 h) and progredient sinusoidal perfusion failure (6 h). Hepatic microvascular injury was accompanied by reduced bile flow and enhanced liver enzyme release. Vitamin E-enriched diet (8000 mg/kg) and even vitamin E-deficient diet did not significantly affect LPS-induced hepatic microvascular cell activation and perfusion failure. Thus, we conclude, that vitamin E is not effective to protect from endotoxin-induced hepatic microvascular dysfunction. Received 7 November 1996; received after revision 30 December 1996; accepted 20 January 1997     

In vivo study of the hypocalcemic, hypophosphoremic, hyperlipemic, and immunogenic activities of the oligopeptide fragment common to ACTH, alpha and beta MSH, and beta lipotropin]

The intravenous injection that was given to rabbits which consisted of 0,5 mg of a common heptapeptide to ACTH4-10, BETA MSH11-17 hormones, and to beta lipotropic47-53 hormone (beta LPH47-53) was followed at the end of an hour by an augmentation of 70% of total lipids, and at the end of two hours by a lowering of calcemia (around 27%) and of phosphoremia (20%). The injection of a tetrapeptide corresponding to only ACTH7-10 bound to a nitrobenzylhydralamin and in presence of a Freund adjuvants has provoked the formation of corresponding antibodies.     

Effect of a restricted diet on the in vitro glucose-induced insulin release of aging rats.

To study the effect of a sudden loss of body weight on the beta-cell function of aging rats, basal and glucose-induced insulin secretion was measured in pancreatic islets obtained from young (2-month-old), adult (12-month-old) and aging (24-month-old) rats, either fed ad libitum or fed a restricted diet (50% caloric restriction). Basal insulin secretion was similar in islets of young, adult and older rats. Glucose stimulated insulin release was significantly reduced in aging rats as compared to young animals. Animals fed a restricted diet showed a prolonged and higher secretory rate during first phase release when compared to animals fed ad libitum.     

Über den Vitamin-B12-Gehalt von Organen verschieden ernährter Ratten

Summary Adult, male rats bred for over 10 generations on a soy meal-corn-diet had vitamin B₁₂ values of liver and kidney about 10 times lower than the controls. If the deficient ration was supplemented with 5µg/kg of B₁₂, these values were still about 1/5 of the controls. 3 weeks on the deficient diet lowered the B₁₂ levels in the livers and kidneys of previously undepleted rats to about 1/2, and a similar diet containing 0.1% of iodized casein lowered these levels to about 1/3 of the normal values but did not lower the B₁₂-concentration of organs of already deficient rats.Rats bred on the deficient diet and receiving for 1 month a supplement of 30µg/kg of vitamin B₁₂ or the stock diet with a similar B₁₂-content, had normal B₁₂-levels in livers and kidneys.