Agc1 In Myelin Synthesis

6.The fatty substances produced by certain glial cells that coat the axons of neurons to insulate, protect, and speed up the neural impulse is the myelin.

7. Myelin Sheath whitish fatty segmented sheath around most long axons. It protects the axon, electrically insulates fibers from one another , and increases the speed of nerve impulse transmition.

When substances like Acetylcholine (Ach) and norepinephrine which are small- molecular neurotransmitters are released into the body they bind to receptors on tissue or neurons through our ANS and PNS system. Ach is released by many PNS neurons and some CNS neurons. In the PNS Ach is an excitatory neurotransmitter at some synapses, such as the neuromuscular junction where it binds to ionotropic receptors which open cation channels. Ach can also be an inhibitory neurotransmitter at other synapses, where it binds to metabotropic receptors while opening potassium channels. The enzyme acetylcholinesterase (AchE) inactivates Ach by splitting into acetate and choline fragments. Norepinephrine (NE) is a biogenic amine; most biogenic amines may cause

Glial cells make up 90 percent of the brain's cells. Glial cells are nerve cells that don't carry nerve impulses. The various glial (meaning "glue") cells perform many important functions, including: digestion of parts of dead neurons, manufacturing myelin for neurons, providing physical and nutritional support for neurons, and more. Types of glial cells include Schwann's Cells, Satellite Cells, Microglia,

Myelin, the common factor in each disease, is a subsatnce that surrounds and insulates axons on some nerve cells, allowing for a faster transporting of signals and proper functioning of the nervous system. A demyelinating disease results in the damage of nerve fibers in the brain and spinal cord due to the myelin sheath being destroyed, which is life threatening.

Myelin, found only in vertebrate nervous systems, is a fatty substance that surrounds the axons and long dendrites of nerves in the brain and spinal cord tissue (4). By lowering the rate at which the axonal membrane absorbs nerve impulses, myelin acts as an insulator, allowing NS potentials to travel rapidly through the nervous system and maintain communication between the brain and the rest of the body (2). This communication between the brain and the rest of the CNS and peripheral nerves is a central

regions of the brain have been stripped of myelin; the fatty covering that insulates the nerve fibers

Brain consists of white matter and gray matter. While gray matter of brain contains nerve cells, white matter of brain contains nerve fibers and myelin. Nerve fibers connect the nerve cells and myelin covers the nerve fibers. Myelin is responsible for conduction of impulses. It also helps in insulation which prevents short circuits.

Areas of high neuroplasticity also tend to be areas of scarce myelination. As mentioned earlier in this paper, these areas both tend to reside within the evolutionarily new neocortex. Neocortical areas exhibit an early and brief myelination cycle as compared to older and deeper brain areas, which exhibit later and extensive myelination. The axons of the neocortex are long, thin, and sparingly myelinated compared to other regions of the brain, as observed through Nissl staining. These Nissl stains verify a pattern of myelination in which the highest cortical areas are the most sparsely myelinated. Perhaps unsurprisingly, the pattern of neural damage, such as neurofibrillary tangles associated with AD, follows the pattern of myelination. In other words, these tangles develop in the areas that are most sparsely myelinated. In contrast, areas of heavy myelination are much more resistant to stressors that cause neuronal degeneration5. It is believed that areas of decreased myelination are characteristic of cells retained in their juvenile state. Without the structural encasing of myelin, these cells are more flexible to changes, and thus have higher plasticity than cells that are heavily myelinated. Therefore, neurons of the neocortex are likely highly plastic largely because of their lower degree of myelination.

Astrocytes are found in the CNS and are shaped like a star. The role of an astrocyte is to support the neurons. They maintain chemical concentrations, remove waste, repairs, as well as playing a role in the blood brain barrier. Oligodendrocytes are found in the CNS and provide the myelin sheath. Schwann cells are found in the PNS and provide the myelin sheath. Both Oligodendrocytes and Schwann cells hold the same responsibilities. The Microglial cell ingests cells and pathogens and play a role in immunity.

Astrocytes are star-shaped cells that make up 20% to 40% of all glia within a particular region of the brain (6). There are 2 main types of astrocytes: fibrous astroglia; which possess long projections and are found in the white matter, as well as protoplasmic astroglia; which have shorter projection and are found in the grey matter of the brain (4). They are known to be very useful as they carry nutrients to neurons (5). Astrocytes also possess several proton and bicarbonate transporters which helps homeostatically control brain pH and their high potassium ion permeability allows them to help maintains neuronal excitability (3). It is clear that astrocytes are an important part of the brain, especially because they also play a key role in helping the

Thus, the immune system cannot distinguish between the two and attack the myelin (Winer 2008).

Despite strong progress in our understanding of psychiatric disorders, moving away from psychological theories of unstable ego or bad mothering1 to clear physical pathologies, the exact etiology of psychiatric diseases remains elusive. The advancements in in-vivo brain imaging and micro-array studies in the past decades have revealed much about the macroscopic and microscopic physical alterations that are happening in human patients, and has put forward a new etiological candidate: myelin.

Human brain consists of billions of cells interconnected together, with each performing its separate functions. It consists of two explicit categories of nerves: neurons and glia cells. Neuron is a single nerve cell in the entire nervous system; which is electrically excitable cell that carries information after being processed via chemical or electrical signals. One of its key characteristics is that it does not undergo cell division. In addition, it maintains a voltage gradient for all the neurons across its membranes. Glia cells, on the other hand, its functionality is to maintain homeostasis.

Oligodendrocyte development is orchestrated by serial stage marker expressions. The expression of 2?,3?-cyclic nucleotide 3?-phosphodiesterase (CNP), an enzyme specifically expressed in oligodendrocytes, has been used as a marker of myelin-forming cells (Bifulco et al., 2002; Vogel et al., 1998) and has been found to be altered in the