Glial Cell Types, Addiction, Optogenetics and Chemogenetics and Beta Amyloid and TAU

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Neuropharmacology Coursework 2
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Question 1: Answer
Glial cells (also called glia) are non-neural cells within the central nervous system and the peripheral nervous system in which electrical impulses are not produced. The central nervous system consists of the brain and the spinal cord, highlighting key locations where these cells are found. Glial cells play different roles. For instance, some have the primary function of providing physical support for the brain, while others provide nutrients to the neurons or regulate the brain's extracellular fluid. There are three types of glial cells in a mature central nervous system: astrocytes, oligodendrocytes, and microglial cells, with each having a specific role. For instance, astrocytes' role is to maintain an ideal chemical environment for neuronal signaling. At the same time, oligodendrocytes provide a lipid-rich layer (myelin) around some axons to speed up the conduction of action potential (1).
On the other hand, multiple sclerosis (MS) is a chronic condition affecting the brain and the spinal cord (2). The condition occurs when the body's immune system attacks the myelin sheath and nerve fibers. The attack by the immune systems leads to inflammation, in which nerve cell processes and myelin are destroyed, resulting in the alteration of electrical signals in the brain. The common symptoms of the disease include fatigue, tingling, weakness, blurred vision, loss of vision, double vision, numbness. Some specific glial cells have significant and specific roles in the pathology of multiple sclerosis.
In recent years, research is increasingly establishing that astrocytes contribute to the MS lesions development. Initially, they were considered to play a role late in MS development by forming a scar post-inflammatory stage (2). However, they are now considered active players in the pathology of the lesion. They are known to secrete various substances, including anti-inflammatory and pro-inflammatory ones. During MS development, astrocytes attract immune cells, damaging a nerve and the area around the active lesion. They result in a lesion scar, which is essential in preventing damage from spreading and acts to prevent the repair of damaged neural.
The role of oligodendrocytes (during normal brain function), as already mentioned, is to assemble myelin (1). Myelin is a multi-layered sheath of membraned wrapped spirally around axonal segments. The purpose of the layer is to hasten the propagation of saltatory impulse. Another function of oligodendrocytes is to support metabolism in myelinated axons, especially during high-frequency spikes in axons (7). During multiple sclerosis, oligodendrocytes are damaged, leading to the loss of myelin in a process called demyelination. Never cells that undergo this process become dysfunctional. Recent research indicates that the earliest pathological event of MS is oligodendrocytes, apoptosis; a combination of rapid demyelination and intense localized microglial activation where peripheral immune cell infiltration is absent (3).
Further, in a normal brain function, the role of microglia is to act as immune...