10-05-2016, 02:26
Dopamine as a Prolactin (PRL) Inhibitor
http://press.endocrine.org/doi/full/10.1210/edrv.22.6.0451
Dopamine binds to type-2 dopamine receptors that are functionally linked to membrane channels and G proteins and suppresses the high intrinsic secretory activity of the pituitary lactotrophs. In addition to inhibiting PRL release by controlling calcium fluxes, dopamine activates several interacting intracellular signaling pathways and suppresses PRL gene expression and lactotroph proliferation.
The critical role of calcium in exocytosis, termed the“ stimulus-secretion coupling” hypothesis, has been long recognized. Calcium is central to all aspects of exocytosis, including rapid fusion and unloading of the vesicles as well as recruitment and translocation of loaded vesicles. Resting levels of cytoplasmic calcium within the neuron are approximately 0.1 μm and can rise to 5–10μ m upon arrival of action potentials (19). Calcium influx occurs through voltage-gated calcium channels and leads to fusion of the synaptic vesicles with the plasma membrane and release of their content to the extracellular space. This is a much faster process than the relatively slow release of peptide or protein hormones from endocrine cells. - See more at: http://press.endocrine.org/doi/full/10.1210/edrv.22.6.0451#sthash.2L5cduVf.dpuf
Protein-protein interactions in neurotransmitter release.
http://www.ncbi.nlm.nih.gov/m/pubmed/10683521/
The arrival of a nerve impulse at a nerve terminal leads to the opening of voltage-gated Ca(2+) channels and a rapid influx of Ca(2+). The increase in Ca(2+) concentration at the active zone from the basal level of 100-200 mM triggers the fusion of docked synaptic vesicles, resulting in neurotransmitter release. A large number of proteins have been identified at nerve terminals and a cascade of protein-protein interactions has been suggested to be involved in the cycling of synaptic vesicle states. Functional studies in last half decade on synaptic-terminal proteins, including Ca(2+) channels, have revealed that the SNARE core complex, consisting of synaptobrevin VAMP, a synaptic vesicle-associated protein, syntaxin and SNAP-25, synaptic membrane-associated proteins, acts as the membrane fusion machinery and that proteins interacting with the SNARE complex play essential roles in synaptic vesicle exocytosis by regulating assembly and disassembly of the SNARE complex.
http://press.endocrine.org/doi/full/10.1210/edrv.22.6.0451
Dopamine binds to type-2 dopamine receptors that are functionally linked to membrane channels and G proteins and suppresses the high intrinsic secretory activity of the pituitary lactotrophs. In addition to inhibiting PRL release by controlling calcium fluxes, dopamine activates several interacting intracellular signaling pathways and suppresses PRL gene expression and lactotroph proliferation.
The critical role of calcium in exocytosis, termed the“ stimulus-secretion coupling” hypothesis, has been long recognized. Calcium is central to all aspects of exocytosis, including rapid fusion and unloading of the vesicles as well as recruitment and translocation of loaded vesicles. Resting levels of cytoplasmic calcium within the neuron are approximately 0.1 μm and can rise to 5–10μ m upon arrival of action potentials (19). Calcium influx occurs through voltage-gated calcium channels and leads to fusion of the synaptic vesicles with the plasma membrane and release of their content to the extracellular space. This is a much faster process than the relatively slow release of peptide or protein hormones from endocrine cells. - See more at: http://press.endocrine.org/doi/full/10.1210/edrv.22.6.0451#sthash.2L5cduVf.dpuf
Protein-protein interactions in neurotransmitter release.
http://www.ncbi.nlm.nih.gov/m/pubmed/10683521/
The arrival of a nerve impulse at a nerve terminal leads to the opening of voltage-gated Ca(2+) channels and a rapid influx of Ca(2+). The increase in Ca(2+) concentration at the active zone from the basal level of 100-200 mM triggers the fusion of docked synaptic vesicles, resulting in neurotransmitter release. A large number of proteins have been identified at nerve terminals and a cascade of protein-protein interactions has been suggested to be involved in the cycling of synaptic vesicle states. Functional studies in last half decade on synaptic-terminal proteins, including Ca(2+) channels, have revealed that the SNARE core complex, consisting of synaptobrevin VAMP, a synaptic vesicle-associated protein, syntaxin and SNAP-25, synaptic membrane-associated proteins, acts as the membrane fusion machinery and that proteins interacting with the SNARE complex play essential roles in synaptic vesicle exocytosis by regulating assembly and disassembly of the SNARE complex.