Water-soluble vitamin homeostasis in fasting northern elephant seals (Mirounga angustirostris) measured by metabolomics analysis and standard methods

Abstract

Despite the importance of water-soluble vitamins to metabolism, there is limited knowledge of their serum availability in fasting wildlife. We evaluated changes in water-soluble vitamins in northern elephant seals, a species with an exceptional ability to withstand nutrient deprivation. We used a metabolomics approach to measure vitamins and associated metabolites under extended natural fasts for up to seven weeks in free-ranging lactating or developing seals. Water-soluble vitamins were not detected with this metabolomics platform, but could be measured with standard assays. Concentrations of measured vitamins varied independently, but all were maintained at detectable levels over extended fasts, suggesting that defense of vitamin levels is a component of fasting adaptation in the seals. Metabolomics was not ideal for generating complete vitamin profiles in this species, but gave novel insights into vitamin metabolism by detecting key related metabolites. For example, niacin level reductions in lactating females were associated with significant reductions in precursors suggesting downregulation of the niacin synthetic pathway. The ability to detect individual vitamins using metabolomics may be impacted by the large number of novel compounds detected. Modifications to the analysis platforms and compound detection algorithms used in this study may be required for improving water-soluble vitamin detection in this and other novel wildlife systems.

Role of Theobromine in Cocoa’s Metabolic Properties in Healthy Rats

“…The pantothenic acid (vitamin B5) is a precursor for the coenzyme A (CoA) and acyl carrier protein, involved in the metabolism of steroids, fatty acids, and phosphatides . CoA is found in the pathway of cholesterol synthesis, amino acid catabolism, and is a crucial substrate in the oxidation of fatty acids . The higher levels of pantothenic acid in cocoa and theobromine groups might be associated with an enhanced fatty-acid metabolism that would partially explain the lower body weight gain and the decrease in hepatic triglycerides as well as plasma cholesterol levels.…”

“…43 CoA is found in the pathway of cholesterol synthesis, amino acid catabolism, and is a crucial substrate in the oxidation of fatty acids. 44 The higher levels of pantothenic acid in cocoa and theobromine groups might be associated with an enhanced fatty-acid metabolism that would partially explain the lower body weight gain and the decrease in hepatic triglycerides as well as plasma cholesterol levels. Also related to the lipid metabolism, we found a negative correlation between the elevated glycocholic acid levels in cocoa and theobromine groups and their reduced fecal fat content.…”

High fatty acid oxidation capacity and phosphorylation control despite elevated leak and reduced respiratory capacity in northern elephant seal muscle mitochondria

“…Seven adult male NES were sampled post-breeding season, May-July, six juvenile male NES were sampled mid-molt, April-May, and four pups were sampled early in the post-weaning fast (pup weaning dates established when their mothers departed for sea); all sampling occurred at Año Neuvo State Reserve, CA. Animals were captured as previously described (Boaz et al, 2012); briefly, an initial dose of Telazol was administered via intramuscular injection and immobilization was maintained through subsequent ketamine injections into the extradural vein. Muscle biopsy sampling was performed using a local anesthetic and samples were taken from the mid-belly of the muscle using an established procedure (described below).…”

Coping with physiological oxidative stress: a review of antioxidant strategies in seals

“…Increased activity and protein expression of several antioxidant enzymes (SOD, catalase, GPx, Prx, GST, GR, G6PDH, glutamate-cysteine ligase =GCL, -glutamyl-transpeptidase: GTT), as well as increased GSH, likely contribute to the prevention of fasting-associated oxidative damage in elephant seal pups (Vázquez-Medina et al 2011c; Vázquez-Medina et al 2010). Increased plasma content of water-soluble vitamins in pups and lactating females (Boaz et al 2012), and the maintenance of elevated levels of high-density lipoproteins in breeding and molting adult males (Tift et al 2011), may also contribute to counteract fasting-induced oxidant production in elephant seals. The understanding of how the antioxidant system of the northern elephant seal is up-regulated in response to prolonged fasting remains elusive, but preliminary studies from our laboratories, along with the present findings, suggest that angiotensin II stimulates Nox4 by increasing transforming growth factor (TGF and that Nox4 may mediate an hormetic response by activating Nrf2 (Figure 2).…”