%0 Journal Article
%T Methylcobalamin: A Potential Vitamin of Pain Killer
%A Ming Zhang
%A Wenjuan Han
%A Sanjue Hu
%A Hui Xu
%J Neural Plasticity
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/424651
%X Methylcobalamin (MeCbl), the activated form of vitamin B12, has been used to treat some nutritional diseases and other diseases in clinic, such as Alzheimer¡¯s disease and rheumatoid arthritis. As an auxiliary agent, it exerts neuronal protection by promoting regeneration of injured nerves and antagonizing glutamate-induced neurotoxicity. Recently several lines of evidence demonstrated that MeCbl may have potential analgesic effects in experimental and clinical studies. For example, MeCbl alleviated pain behaviors in diabetic neuropathy, low back pain and neuralgia. MeCbl improved nerve conduction, promoted the regeneration of injured nerves, and inhibited ectopic spontaneous discharges of injured primary sensory neurons. This review aims to summarize the analgesic effect and mechanisms of MeCbl at the present. 1. Introduction Vitamin B12 had been usually treated as sport nutrition, and used to keep old people from getting anemic in past years. Vitamin B12 was regarded as painkilling vitamin in some countries from 1950. Recently studies have shown that vitamin B12 played a key role in the normal functioning of the brain and nervous system and the formation of blood. Vitamin B12 is normally involved in several metabolisms such as DNA synthesis and regulation, fatty acid synthesis, and energy production. Vitamin B12 has some analogs including cyanocobalamin (CNCbl), methylcobalamin (MeCbl), hydroxocobalamin (OHCbl), and adenosylcobalamin (AdoCbl). In mammalian cells, CNCbl and OHCbl are inactive forms and AdoCbl acts as a coenzyme of methylmalonyl Co-A mutase in mitochondria. However, vitamin B12 was not used directly in human body, and it should be translated into activating forms such as MeCbl or AdoCbl. MeCbl differs from vitamin B12 in that the cyanide is replaced by a methyl group (Figure 1) [1]. It is a coenzyme of methionine synthase, which is required for the formation of methionine from homocysteine in the methylation cycle which involves methylation of DNA or proteins [2¨C5]. Compared with other analogs, MeCbl is the most effective one in being uptaken by subcellular organelles of neurons. Therefore, MeCbl may provide better treatments for nervous disorders through effective systemic or local delivery. Figure 1: The chemical structure of MeCbl. As an auxiliary agent, MeCbl has been always used to treat many diseases, such as B12 deficiency and Alzheimer¡¯s disease syndromes [6, 7]. L-methylfolate, MeCbl, and N-acetylcysteine improved memory, emotional functions, and communication with other people among Alzheimer¡¯s patients [7, 8]. MeCbl also has
%U http://www.hindawi.com/journals/np/2013/424651/