Distribution of vitamin C is tissue specific with early saturation of the brain and adrenal glands following differential oral dose regimens in guinea pigs

Abstract

Vitamin C (VitC) deficiency is surprisingly common in humans even in developed parts of the world. The micronutrient has several established functions in the brain; however, the consequences of its deficiency are not well characterised. To elucidate the effects of VitC deficiency on the brain, increased knowledge about the distribution of VitC to the brain and within different brain regions after varying dietary concentrations is needed. In the present study, guinea pigs (like humans lacking the ability to synthesise VitC) were randomly divided into six groups (n 10) that received different concentrations of VitC ranging from 100 to 1500 mg/kg feed for 8 weeks, after which VitC concentrations in biological fluids and tissues were measured using HPLC. The distribution of VitC was found to be dynamic and dependent on dietary availability. Brain saturation was region specific, occurred at low dietary doses, and the dose -concentration relationship could be approximated with a three-parameter Hill equation. The correlation between plasma and brain concentrations of VitC was moderate compared with other organs, and during non-scorbutic VitC deficiency, the brain was able to maintain concentrations from about one-quarter to half of sufficient levels depending on the region, whereas concentrations in other tissues decreased to one-sixth or less. The adrenal glands have similar characteristics to the brain. The observed distribution kinetics with a low dietary dose needed for saturation and exceptional retention ability suggest that the brain and adrenal glands are high priority tissues with regard to the distribution of VitC.

l-dehydroascorbic acid can substitute l-ascorbic acid as dietary vitamin C source in guinea pigs

“…The capacity of the brain to hold on to vitamin C is widely acknowledged [32] , [33] , [34] and our confirmatory finding supports the physiological relevance of the data. Moreover, we recently reported that saturation of the brain occurs faster than for most other tissues [35] . It can also be extracted from Fig.…”

High-fat but not sucrose intake is essential for induction of dyslipidemia and non-alcoholic steatohepatitis in guinea pigs

“…Food intake in each group was estimated daily by weighing feed-remains prior to refill. After either 16 or 25 weeks, guinea pigs were semi-fasted over-night (no feed, but access to hay), pre-anaeshetized with 0.08 ml/kg BW Zoletil-mix, placed on isoflurane and euthanized by decapitation following an intra-cardial blood sample as previously described [ 11 , 17 ]. Organs were rapidly collected, rinsed in phosphate buffered saline, weighed and stored at −80 °C or in paraformaldehyde for histological examinations.…”

Discrepancies in global vitamin C recommendations: a review of RDA criteria and underlying health perspectives

“…These transporters are high affinity transporters that are capable of maintaining a many fold higher intracellular concentration of vitamin C compared to plasma even during periods of reduced intake (reviewed in (Lindblad, Tveden-Nyborg, and Lykkesfeldt 2013)). As studied in detail in guinea pigs, that like humans do not have the ability to biosynthesize vitamin C, the brain is a particularly relevant example as it has a very high vitamin C content and a high preference in the systemic homeostasis of vitamin C (Hasselholt, Tveden-Nyborg, and Lykkesfeldt 2015;Frikke-Schmidt et al 2011). Such deep compartments do not equilibrate rapidly with blood and other compartments and are therefore not assessed in shortterm isotope dilution experiments such as those conducted by Kallner and others.…”