Sst, short for somatostatin, is a cyclic peptide that inhibits the release of hormones and neurotransmitters by binding to one of five canonical G protein-coupled SST receptors (SSTR1 to SSTR5) [3,4]. It negatively regulates cell proliferation and the release of multiple hormones, and is involved in the GH-IGF-SST system which plays a crucial role in liver growth, development and hepatocarcinogenesis [2,4]. Genetically modified mouse models are valuable for studying Sst's functions.

In mice, excitatory SST neurons in the medial paralemniscal nucleus (MPLSST neurons) promote self-grooming and encode reward. Loss of function of MPLSST neurons impairs both self-grooming and post-stress anxiety alleviation, revealing a dual role of the CeA-MPLSST-VTADA circuit in self-grooming and post-stress anxiety regulation [1].

In conclusion, Sst is important for regulating hormone release, cell proliferation and is involved in anxiety-related behaviors as demonstrated by mouse models. Understanding Sst's functions can potentially provide insights into the mechanisms of stress-related disorders and hepatocarcinogenesis.

References:

1. Sun, Jingjing, Yuan, Yuan, Wu, Xiaohua, Xu, Tian-Le, Huang, Ju. 2022. Excitatory SST neurons in the medial paralemniscal nucleus control repetitive self-grooming and encode reward. In Neuron, 110, 3356-3373.e8. doi:10.1016/j.neuron.2022.08.010. https://pubmed.ncbi.nlm.nih.gov/36070748/

2. Pivonello, Claudia, De Martino, Maria Cristina, Negri, Mariarosaria, Colao, Annamaria, Pivonello, Rosario. 2014. The GH-IGF-SST system in hepatocellular carcinoma: biological and molecular pathogenetic mechanisms and therapeutic targets. In Infectious agents and cancer, 9, 27. doi:10.1186/1750-9378-9-27. https://pubmed.ncbi.nlm.nih.gov/25225571/

3. Solarski, Michael, Williams, Declan, Mehrabian, Mohadeseh, Wille, Holger, Schmitt-Ulms, Gerold. 2019. The human brain somatostatin interactome: SST binds selectively to P-type family ATPases. In PloS one, 14, e0217392. doi:10.1371/journal.pone.0217392. https://pubmed.ncbi.nlm.nih.gov/31136617/

4. Sun, Lichun, Coy, David H. . Somatostatin and its Analogs. In Current drug targets, 17, 529-37. doi:. https://pubmed.ncbi.nlm.nih.gov/26951062/