11/9/2023 0 Comments Hippocampus band fort collinsThey belong to the solute carrier family 17, which is a sodium-dependent phosphate transporter family. On the contrary, VGLUTs are expressed on neuronal synaptic vesicles’ membrane and thought to be characteristic to neurons only. EAATs, being responsible for the termination of the synaptic signal, can be found in the plasma membrane of pre- and postsynaptic neurons, as well as in glial cells, and thus cannot be used to characterise glutamatergic neurons. Two distinct protein families transport Glu through membranes: the excitatory amino acid transporters (EAATs) and the vesicular glutamate transporters (VGLUTs). One of the most abundant types of neurons in the CNS is the glutamatergic cells, which exert excitation in most cases via the release of Glu. Therefore, neuron classification is based mainly on the transporter proteins that pack the neurotransmitters into vesicles, from which the molecules are later released into the synaptic cleft. As these “classical” neurotransmitters are small molecules, they are often intermediates of the metabolism and thus detectable in all cells. However, even today, it is still regarded such that neurons have one main “classical” neurotransmitter type (e.g., excitatory glutamate (Glu) or inhibitory gamma aminobutyric acid (GABA)) and express numerous other secondary ones, mainly peptides. While Dale’s principle originally stated that one neuron utilises one neurotransmitter, we now know that a cell can express multiple different molecules to communicate. In the central nervous system (CNS), neurons are classified based on the neurotransmitters they express. However, further studies making use of more specific tools (e.g., Cre-mice, opto- and chemogenetics) are needed to confirm these assumptions. Indirect information from anatomical studies and KO mice strains suggests the contribution of local VGLUT3-positive hippocampal neurons as well as afferentations in these events. This hippocampal glutamatergic network plays a pivotal role in several important processes (e.g., learning and memory, emotions, epilepsy, cardiovascular regulation). Although VGLUT3-expressing neurons are detectable in the hippocampus, most of the hippocampal VGLUT3 positivity can be found on nerve terminals, presumably coming from the median raphe. However, its involvement in learning and memory can only be assumed based on its prominent hippocampal presence. Its contribution to sensory processes (including seeing, hearing, and mechanosensation) is well characterised. Glutamate, manipulated by VGLUT3, can modulate the packaging as well as the release of other neurotransmitters and serve as a retrograde signal through its release from the somata and dendrites. Among the three subtypes, VGLUT3 is unique, co-localising with other “classical” neurotransmitters, such as the inhibitory GABA. Neurons using glutamate as a neurotransmitter can be characterised by vesicular glutamate transporters (VGLUTs). Glutamate is the most abundant excitatory amino acid in the central nervous system.
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