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Somatostatin is a synthetic cyclic 14 amino acid peptide (identical in structure and activity to naturally occurring somatostatin). Naturally occurring somatostatin (also known as growth hormone-inhibiting hormone) is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G protein-coupled somatostatin receptors and inhibition of the release of numerous secondary hormones. Somatostatin inhibits insulin and glucagon secretion. >> Read More
Somatostatin, a therapeutic peptide drug, was entrapped within polymeric microspheres made from high molecular weight poly (D,L-lactide/glycolide) (PLGA) or low molecular weight poly (D,L-lactide) (PLA) by various modifications of the O/W-solvent evaporation method. The drug was either dispersed as solid (dispersion method), dissolved with the aid of a co-solvent (co-solvent method) or emulsified as an aqueous solution (W/O/W-multiple emulsion method) in the organic polymer solution prior to emulsification into an external aqueous phase. Additionally, a non-aqueous O/O-method was evaluated for the formation of the microspheres. Acceptable encapsulation efficiencies were obtained with all methods, regardless of the physical state of drug and the polymer type. The total volume of organic solvent and the co-solvent content were found to be important preparation factors of the O/W-co-solvent method. A more lipophilic solvent system appeared to favor efficient drug encapsulation. Replacing the widely used but toxic methylene chloride with ethyl acetate resulted in significantly lower drug loadings. The preparation method substantially affected the morphology of the microspheres and the drug release.
Herrmann, J., & Bodmeier, R. (1998). Biodegradable, somatostatin acetate containing microspheres prepared by various aqueous and non-aqueous solvent evaporation methods. European Journal of Pharmaceutics and Biopharmaceutics, 45(1), 75-82.
We previously demonstrated that phosphorylation of somatostatin receptor 2A (sst2A) is rapidly increased in transfected cells both by agonist and by the protein kinase C (PKC) activator phorbol myristate acetate (PMA). Here, we investigate whether PKC-mediated receptor phosphorylation is involved in the homologous or heterologous regulation of endogenous sst2 receptors in AR42J pancreatic acinar cells upon stimulation by agonist or by cholecystokinin (CCK) or bombesin (BBS). Somatostatin, PMA, CCK, and BBS all increased sst2A receptor phosphorylation 5- to 10-fold within minutes. Somatostatin binding also caused rapid internalization of the ligand-receptor complex, and PMA, CCK, and BBS all stimulated this internalization further.
Elberg, G., Hipkin, R. W., & Schonbrunn, A. (2002). Homologous and heterologous regulation of somatostatin receptor 2. Molecular Endocrinology, 16(11), 2502-2514.