Effects Of AA Supplementation Research Articles

Effect of arginine or glutamine supplementation and milk feeding allowance on small intestine development in calves

The development of the small intestine (SI) is important for the health and growth of neonatal calves. This study evaluated the effect of arginine (Arg) and glutamine (Gln) supplementation and 2 levels of milk allowance on the histomorphological development of the SI in preweaning calves. Sixty mixed-sex Friesian × Jersey calves (3-5 d of age) were offered reconstituted whole milk (125 g/L, 26% fat, 26% protein) at either high (20% of arrival body weight/d; HM) or low (10% of arrival body weight/d; LM) milk allowance without (Ctrl) or with supplementary Arg or Gln (at 1% of milk dry matter) in a 2 × 3 factorial design (n = 10/treatment). After 35 d on the diets, all calves were slaughtered to collect tissues for examination of SI development. Calves in the HM group had higher milk intake, total weight gain, and average daily gain compared with LM calves, but no effect of AA supplementation nor an interaction between milk allowance and AA supplementation was observed. For the duodenum, we observed an AA by milk allowance interaction for villus height and width, and goblet cell number per villus (HM-Arg > HM-Gln > HM-Ctrl), and villus height to crypt depth ratio (HM-Arg > HM-Gln = HM-Ctrl), but no effect of AA supplementation in the LM group. Goblet cell numbers per 100 µm of SI were greater in Arg-supplemented calves than in unsupplemented controls, with Gln-supplemented calves intermediate to but not different from the other groups. Epithelium thickness was greater in LM than in HM calves. Villus density, crypt depth, and muscle thickness did not differ between groups. For the jejunum, there was an AA by milk allowance interaction for villus height, villus surface area, and villus height to crypt depth ratio (HM-Arg = HM-Gln > HM-Ctrl), with no effect of AA supplementation in the LM groups. Amino acid supplementation affected goblet cell number per villus (HM-Gln > HM-Ctrl calves, HM-Arg intermediate), and both LM-Arg and LM-Gln calves had greater numbers than LM-Ctrl calves. Villus width, crypt depth, and muscle thickness were greater in HM than LM calves but there was no effect of AA supplementation. Villus density, goblet cell number per 100 µm of SI, and epithelium thickness were unaffected by AA supplementation and milk allowance. Milk allowance and AA supplementation had no effect on SI morphology in the ileum. Increasing milk allowance improved villus height, width, and surface area but only in Arg- or Gln-supplemented calves, not in control calves. The observed changes in development may be important for intestinal functionality, integrity, and barrier function in preweaning calves, potentially through increased cell growth and proliferation or reduced levels of cellular atrophy.

Long-term effects of vitamin C supplementation on glomerular changes in streptozotocin-induced diabetic rats

Background: Deficiency of vitamin C (L-ascorbic acid; AA) may induce renal glomular dysfunction in diabetes. Few data are available for the role of continuous upplementation of AA on glomerular dysfunction and pathologyinduced during diabetes. Objective: To investigate long-term effects of AA supplementation on glomerular changes in streptozotocin (STZ)-induced diabetic rats. Methods: Diabetes was induced in Sprague-Dawley rats (180-220 g) by injection of STZ (55 mg/kg bw, iv). The rats were divided into controls (CON), AA-supplemented controls (CON-AA), diabetic (STZ) and AA-supplemented diabetic rats (STZ-AA). AA (1 g/L) was continuously supplemented to the rats for 4, 8, 16 and 24 weeks. The glomerular filtration rate (GFR), effective renal plasma flow (ERPF), renal vascular resistance (RVR) malondialdehyde (MDA) and transforming growth factor-β1 (TGF-β1) levels were measured in the renal cortex. Glomerular morphology was examined histologically. Renal hypertrophic index was calculated using kidney-to-body weight ratio (KW/BW). Results: Decreases in GFR and ERPF were ameliorated at week 16 and deteriorated at week 24 after AA supplementation in STZ-AA rats. High blood glucose concentration was attenuated only at week 16. MAD and TGF-β1 levels in renal cortex decreased significantly in STZ-AA rats at week 16 but not at week 24. The number of abnormal glomeruli and KW/BW decreased significantly at week 16 in STZ-AA rats. Conclusion: Long-term supplementation of AA may ameliorate the glomerular changes induced by diabetes.

Tissue-specific effect of ascorbic acid supplementation on the expression of cytochrome P450 2E1 and oxidative stress in streptozotocin-induced diabetic rats

Here, we investigated the effect of l-ascorbic acid (AA) supplementation on the CYP2E1 expression level and oxidative stress in various tissues such as the liver, kidney, pancreas, and brain of streptozotocin (STZ)-induced diabetic rats. An increased cytochrome P450 2E1 (CYP2E1) expression level with a concomitant increase in the production of reactive oxygen species were found in all the tissues of STZ-induced diabetic rats tested compared with an untreated control, suggesting the possible diabetes-induced tissue injury. In contrast, the AA supplementation to the diabetic rats alleviated these experimental parameters in a tissue-specific manner. AA affected the liver most severely followed by the kidney. There was little or no effect of AA supplementation on the brain and pancreas. The circulation level of the ketone bodies, inducers of CYP2E1, was also decreased by AA supplementation compared with those of the diabetic rats. Therefore, the suppression of ketone production by AA can be one of the mechanisms of a reduction in CYP2E1. These results suggest that AA plays an important role in reducing elevated CYP2E1 expression level and the oxidative stress mediated by type 1 diabetes with a tissue-specific variation.