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Diphenyl diselenide and ascorbic acid changes deposition of selenium and ascorbic acid in liver and brain of mice.

Sodium selenite (Na2SeO3) is the selenium form used in the composition of dietary supplements, and diphenyl diselenide (PhSe)2 is an important intermediate in organic synthesis, which increases the risk of human exposure to this chemical in the workplace. These compounds have been reported to inhibit the cerebral and hepatic aminolevulinic acid dehydratase (ALA-D) in vitro, and now we show that ascorbic acid can reverse some alterations caused by in vivo selenium exposure, but not ALA-D inhibition. The effect of Na2SeO3 or (PhSe)2 and ascorbic acid on selenium distribution, total non-protein thiol, ascorbic acid content (liver and brain) and haemoglobin was also examined. Mice were exposed to 250 micromol/kg (PhSe)2, or 18.75 micromol/kg Na2SeO3 subcutaneously, and to ascorbic acid, twice a day, 1 mmol/kg intraperitonially, for 10 days. Hepatic ALA-D of mice treated with (PhSe)2 was inhibited about 58% and similar results were observed in the animals that received ascorbic acid supplementation (P<0.01, for (PhSe)2-treated and (PhSe)2+ascorbic acid-treated mice). The haemoglobin content decreased after treatment with (PhSe)2 (P<0.01). However, the haemoglobin content of the (PhSe)2+ascorbic acid group was significantly higher than in the (PhSe)2-treated mice (P<0.05), and similar to control (P>0.10). Ascorbic acid treatment decreased significantly the hepatic and cerebral deposition of Se in (PhSe)2-exposed mice (P<0.01). Hepatic non-protein thiol content was not changed by treatment with (PhSe)2, ascorbic acid or (PhSe)2+ascorbic acid. Hepatic content of ascorbic acid was twice that in mice that received (PhSe)2, independent of ascorbic acid treatment (P<0.001). The results of this study suggest that vitamin C may have a protective role in organodiselenide intoxication.

Animals↗

gamma-Linoleic acid and ascorbic acid ameliorate the effects of experimental diabetes on electrolyte and bone homeostasis in pregnant rats.

Experimental diabetes in rats is associated with excessive electrolyte loss in the urine, which is further accentuated by pregnancy, particularly of Ca. Supplementation with essential fatty acids and antioxidants has proven beneficial in treating several types of complications, including nephropathy. The present study investigated the effect of gamma-linoleic acid (GLA; 500 mg/kg per day; group DG) and ascorbate (290 mg/kg per day; group DA), alone and in combination (group DGA), as well as ascorbyl-GLA (790 mg/kg per day; group DASG), on urinary electrolyte output and skeletal composition in pregnant streptozotocin-diabetic rats. Urine was collected in metabolism cages before and throughout pregnancy. Diabetic rats (DP) increased their urine volume as compared with control (CP) throughout the experiment, reaching an output of more than 13 times that of the control group by the end of pregnancy (CP 24+/-4, DP 316+/-21, DG 223+/-21, DA 221+/-14, DASG 163+/-17, DGA 220+/-19 ml urine/24 h). Concomitant with increased urine volume was a reduction of urinary Na (CP 47+/-14, DP 22+/-5 mmol/l), K (CP 210+/-34, DP 31+/-1 mmol/l) and Mg (CP 14+/-1, DP 3.8+/-0.2 mmol/l) concentration, but not of Ca concentration (CP 5.4+/-1.5, DP 6.3+/-0.6 mmol/l), and hence total Ca loss was relatively most severe. All the treatments reduced urine volume with no effects on electrolyte concentration as compared with DP, with no significant difference between the treatments. A reduced bone size and bone Ca content was partially ameliorated by the diet supplementation. We have concluded that GLA and ascorbate, alone or in combination, prevent urinary electrolyte loss in pregnant rats and do so by reducing urine production.

Animals↗

Seasonal variations in ascorbic acid status and breast milk ascorbic acid levels in rural Gambian women in relation to dietary intake.

Vitamin C intakes from mangoes and oranges, and plasma and breast milk ascorbic acid concentrations were measured at regular intervals in a cohort of pregnant and lactating women in Keneba and Manduar, two neighbouring rural Gambian villages. Extremely wide seasonal variations in plasma ascorbic acid levels were observed, the peak during the mango season in May and June attaining mean levels of 1.4 mg/dl, while the lowest levels, averaging only 0.2 mg/dl, were observed during the rainy season, during September and October. Parallel, but less pronounced variations were observed in breast milk ascorbate levels. A vitamin-fortified milk and biscuit supplement, given first to the lactating, and later to the pregnant, mothers in Keneba, which provided about 35 mg ascorbic acid per day, failed to produce any major improvement in plasma ascorbic acid levels during the rainy season, although there was some evidence for an improvement in breast milk levels. It is therefore likely that considerably greater intakes are required to maintain satisfactory maternal circulating levels and biochemical status during this critical period.

Ascorbic Acid↗

Ascorbic acid in thyroidectomized rats. II) Ascorbic acid status of the storage tissues and hepatic biosynthesis of glucuronic acid.

Depletion of ascorbic acid from adrenals, brain and epididymis along with loss in weight were noticed in the state of thyroidectomy. This decrease appears to be due to an effect of thyroidectomy on the membrane integrity since the membrane bound sialic acid was found to be significantly lowered in these tissues as a consequence of the elevated activity of sialidase. Thyroidectomy was also found to cause an adverse effect on the activities of hepatic UDP-glucuronyl transferase and beta-glucuronidase with no alteration in UDP-glucose dehydrogenase.

Adrenal Glands↗