Neurotransmitters function, lipid regulation

Vesicular proteins and lipids that are destined for the plasma membrane leave the TGN sorting station continuously. Incorporation into the plasma membrane is typically targeted to a particular membrane domain (dendrite, axon, presynaptic, postsynaptic membrane, etc.) but may or may not be triggered by extracellular stimuli. Exocytosis is the eukaryotic cellular process defined as the fusion of the vesicular membrane with the plasma membrane, leading to continuity between the intravesicular space and the extracellular space. Exocytosis carries out two main functions it provides membrane proteins and lipids from the vesicle membrane to the plasma membrane and releases the soluble contents of the lumen (proteins, peptides, etc.) to the extracellular milieu. Historically, exocytosis has been subdivided into constitutive and regulated (Fig. 9-6), where release of classical neurotransmitters at the synaptic terminal is a special case of regulated secretion [54]. 

Specific lipid messengers are cleaved from reservoir phospholipids by phospholipases upon activation by various stimuli. These stimuli include neurotransmitters, neurotrophic factors, cytokines, membrane depolarization, ion channel activation and others. Lipid messengers regulate and interact with multiple other signaling cascades, contributing to the development, differentiation, function, protection and repair of the cells of the nervous system. 

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