Riboflavin brain

Pyridoxine phosphate oxidase is a flavoprotein, and activation of the erythrocyte apoenzyme by riboflavin 5 -phosphate in vitro can be used as an index of riboflavin nutritional status (Section 7.4.3). However, even in riboflavin deficiency, there is sufficient residual activity of pyridoxine phosphate oxidase to permit normal metabolism ofvitamin Be (Lakshmi and Bamji, 1974). Pyridoxine phosphate oxidase is inhibited by its product, pyridoxal phosphate, which binds a specific lysine residue in tbe enzyme. In tbe brain, tbe Ki of pyridoxal phosphate is of the order of 2 /xmol per L - the same as the brain concentration of free and loosely bound pyridoxal phosphate, suggesting that this inhibition may be a physiologically important mechanism in the control of tissue pyridoxal phosphate (Choi et al., 1987). 

Vitamin B complex is the collective term for a number of water-soluble vitamins found particularly in dairy products, cereals and liver.Vitamin B (thiamine) is used by mouth for dietary supplement purposes and by injection in emergency treatment of Wernicke-Korsakoff syndrome. Vitamin B2 (riboflavin) is a constituent of the coenzyme FAD (flavine adenine dinucleotide) and FMN (flavine mononucleotide) and is therefore important in cellular respiration. Vitamin Be (pyridoxine) is a coenzyme for decarboxylases and transamination, and is concerned with many metabolic processes. Overdose causes peripheral neuropathy. It may be used medically for vomiting and radiation sickness and for premenstrual tension. Pyridoxine has a negative interaction with the therapeutic use of levodopa in parkinsonism by enhancing levodopa decarboxylation to dopamine in the periphery, which does not then reach the brain. The antitubercular drug isoniazid interferes with pyridoxine, and causes a deficiency leading to peripheral neuritis that may need to be corrected with dietary supplements. Vitamin B ... 

Sea lettuces are a source of vitamins from group B (MacArtain et al, 2007 McDermid and Stuercke, 2003). For instances, Ulva lactuca contain high amount of cobalamin or vitamin B12. Vitamin B12 plays a key role in homeostasis of the brain and nervous system, and for the formation of blood (Scalabrino, 2009). Daily ingestion of 1.4 g/day of Ulva lactuca will be enough to meet the daily requirements of vitamin B12 (MacArtain et al, 2007). One of the most important vitamins B occurring in Ulva reticulata is riboflavin (vitamin B2). Vitamin B2 deficiency is often endemic in human... 

An investigation was made by Schaus and Kirk (1956) of the total rilio-flavin tissue concentrations in 89 samples of the cerebral cortex, 86 samples of the heart, and 88 samples of the pectoral muscle derived from individuals ranging in age from 7 days to 92 years. The mean riboflavin values observed in human subjects for the various decades ai e presented in Table VIII. It will be seen from the recorded data that no significant changes with age were found in the riboflavin levels of the brain tissue (r = -f 0.14 t = 1.32) or skeletal muscle (r = —0.20 I = 1.08). A tendency was noted for the riboflavin values of the myocardium to decrease after the age of 80 years, but the number of samples derived from individuals above 80 years was too. small to permit definite conclusions in this respect the calculated coefficient of correlation (r), age myocardial riboflavin concentnition for the 86 samples analyzed, was —0.18 (< = 1.67). 

During this period of rapid somatic growth, there is a high rate of brain growth and evidence further suggests that certain vitamins such as folate and riboflavin and at least one trace element, zinc, may be particularly active in the normal process of protein synthesis and cell replication. 

For the uptake of riboflavin by brain cells, it is most important to maintain homeostasis. The concentration of riboflavin in the brain remains constant, both at times of riboflavin deficiency and after massive intravenous applications. In rat brains, more than 90% of total riboflavin is found as FAD and FMN (Ball 2004b). 

Cerebrospinal fluid is constantly produced and exchanged, and therefore riboflavin is continuously supplied and crosses the blood-brain barrier. The mechanism of this process was examined in vitro in rabbit brain slices (Speetor 1980a), rat brain endothelial cells (RBE4 cells) (Patel et al. 2010), and isolated rabbit choroid plexus (Speetor and Boose 1979). 

The same phenomenon was observed after injeetions of riboflavin into the ventricular cerebrospinal fluid of anaesthetized rabbits only some of the riboflavin was accumulated in the choroid plexus and most was removed (Speetor 1980b). Thus, support of brain homeostasis results from transport of riboflavin both from blood into the choroid plexus and in the opposite direction. 

The saturable system of crossing the cells was also observed for brain slices (cut in two different directions). The process was ATP dependent (inhibited by DNP and decreased temperature) because absorbed intracellular riboflavin is rapidly converted into FMN and in turn into FAD. Additionally, neither the absorption of FAD nor FMN is possible (Speetor 1980a, 1980b). 

Relevant in making the maintenance of brain homeostasis possible is the third identified human riboflavin transporter hRFT3 (GPR172A), which is expressed in the brain and salivary gland. It has the same substrate specificity as hRFTl and hRFT2, and functional characteristics similar to those of hRFTl (Yao et al. 2010). 

Additionally, passive diffusion was proven during riboflavin oversupplementation in small and large intestine, brain and renal cells. Receptor-mediated transport is suggested as an additional mechanism of riboflavin uptake and is recognised in both the small and large intestine and in placental cells. 

Patel, M.R., Mandava, N., Pal, D., and Mitra, A.K., 2010. Identification and functional characterization of a carrier mediated transport system for riboflavin on rat brain endothelial cells. In Pharmaceutical Sciences Word Congress Abstracts, AAPS Journal M1209. 

Spector, R., 1980a. Riboflavin accumulation by rabbit brain slices in vitro. Journal of Neurochemistry. 34 1768-1771. 

Yao, Y., Yonezawa, A., Yoshimatsu, H., Masuda, S., Katsura, T., and Inui, K., 2010. Identification and comparative functional characterization of a new human riboflavin transporter hRFT3 expressed in the brain. Journal of Nutrition. 140 1220-1226. 

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