lördag 9 april 2016

Somatostatiini on rikkipitoinen molekyyli, hermonvälittäjäaine

( Neurohormoni, jolla on  dieetärisesti vaativa rakenne. 8 aminohappoa  14.sta on essentielliä  ja lisäksi  vielä 2 cysteiiniä.  Näyttää olevan yhden  genin tuote.  Inhibitorinen   vaikutus harmaan solukon hormonaalisiin  erityksiin , myös GI-alueella vaikuttaa , vaimentaa insuliinieritystä.
Neuron. 2013 Jan 9;77(1):155-67. doi: 10.1016/j.neuron.2012.11.004.
Neocortical somatostatin-expressing GABAergic interneurons disinhibit the thalamorecipient layer 4.
Subtypes of GABAergic interneurons (INs) are crucial for cortical function, yet their specific roles are largely unknown. In contrast to supra- and infragranular layers, where most somatostatin-expressing (SOM) INs are layer 1-targeting Martinotti cells, the axons of SOM INs in layer 4 of somatosensory cortex largely remain within layer 4. Moreover, we found that whereas layers 2/3 SOM INs target mainly pyramidal cells (PCs), layer 4 SOM INs target mainly fast-spiking (FS) INs. Accordingly, optogenetic inhibition of SOM INs in an active cortical network increases the firing of layers 2/3 PCs whereas it decreases the firing of layer 4 principal neurons (PNs). This unexpected effect of SOM INs on layer 4 PNs occurs via their inhibition of local FS INs. These results reveal a disinhibitory microcircuit in the thalamorecipient layer through interactions among subtypes of INs and suggest that the SOM IN-mediated disinhibition represents an important circuit mechanism for cortical information processing.
Copyright © 2013 Elsevier Inc. All rights reserved.

The hormone somatostatin has active 14 aa and 28 aa forms that are produced by alternate cleavage of the single preproprotein encoded by this gene. Somatostatin is expressed throughout the body and inhibits the release of numerous secondary hormones by binding to high-affinity G-protein-coupled somatostatin receptors. This hormone is an important regulator of the endocrine system through its interactions with pituitary growth hormone, thyroid stimulating hormone, and most hormones of the gastrointestinal tract. Somatostatin also affects rates of neurotransmission in the central nervous system and proliferation of both normal and tumorigenic cells. [provided by RefSeq, Jul 2008]

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