Secretin (swine), a neuroendocrine hormone, was the first hormone to be identified and is mainly secreted by S cells located in the duodenal mucosa. Secretin is also a 27-amino acid (AA) polypeptide that works on the secretin receptor. Secretin is expressed in all mature enteroendocrine cell subsets and can be promoted by fatty acids. Secretin stimulates the secretion of water and bicarbonate from the pancreas. Secretin plays multiple roles in organs and may be utilized in studies of the digestive system, central nervous system, and energy metabolism.

Physicochemical Properties

Molecular Formula	C130H220N44O41.6[C4H7NO4]
Molecular Weight	3854.02407999997
Exact Mass	3053.65
CAS #	17034-35-4
Appearance	White to off-white solid powder
HS Tariff Code	2934.99.9001
Storage	Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month
Shipping Condition	Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Biological Activity

ln Vitro	Secretin (porcine) (10−7M, 10−6M; 24 to 72 hours and 7 days) interacts with the secretin receptor (SR) to promote bile growth; cAMP-dependent signaling is downregulated to diminish bile proliferation by knocking down SR[2]. Large murine biliary cell lines and human HIBEpiC are more proliferative when exposed to secretin (10−7M, 10−6M; 24 to 72 hours and 7 days) [2][3][4]. The use of immunofluorescence
ln Vivo	Pig secretin (2.5 nM/kg, body weight/day, mini-osmotic pump, for 1 week) stimulates the expression of microRNA let7a and microRNA 125b in mice, which in turn promotes the proliferation of cholangiocytes [2].
Cell Assay	Immunofluorescence[2] Cell Types: Large mouse cholangiocyte cell line Tested Concentrations: 10−7M, 10−6 M Incubation Duration: 24 to 72 hrs (hours) and 7 days Experimental Results: Increased cholangiocyte proliferation. Cell proliferation assay[2] Cell Types: Human HIBEpiC and Large Murine Cholangiocarcinoma Cell Line Tested Concentrations: 10−7M, 10−6M Incubation Duration: 24 to 72 hrs (hours) and 7 days Experimental Results: Untransfected, vector-transfected, and secretin Increased proliferation of shRNA-containing bile duct cells and HiBEpiC compared with cell lines treated with BSA (basal).
Animal Protocol	Animal/Disease Models: Sct+/- mice [2] Doses: 2.5 nM/kg Route of Administration: 2.5 nM/kg, body weight/day, mini-osmotic pump for 1 week Experimental Results: Post-BDL cholangiocyte and S cell supernatants and serum and levels in bile were increased in control mice. BDL Sct+/- mice have lower IBDM, diminished proliferation, and diminished vascular endothelial growth factor A (VEGFA) and nerve growth factor (NGF) production. Regulates the expression of VEGF and NGF and is negatively correlated with microRNA 125b and let7a levels in liver tissue [2].
References	[1]. Secretin as a Satiation Whisperer With the Potential to Turn into an Obesity-curbing Knight. Endocrinology. 2021 Sep 1;162(9):bqab113. [2]. Secretin stimulates biliary cell proliferation by regulating expression of microRNA 125b and microRNA let7a in mice. Gastroenterology. 2014 Jun;146(7):1795-808.e12. [3]. Morphological, molecular, and functional heterogeneity of cholangiocytes from normal rat liver. Gastroenterology. 1996 May;110(5):1636-43. [4]. Knockout of secretin receptor reduces large cholangiocyte hyperplasia in mice with extrahepatic cholestasis induced by bile duct ligation. Hepatology. 2010 Jul;52(1):204-14.

Solubility Data

Solubility (In Vitro)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Solubility (In Vivo)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples. Injection Formulations (e.g. IP/IV/IM/SC) Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] *Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline) Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline) Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline) Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil) Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Oral Formulations Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). Oral Formulation 3: Dissolved in PEG400 Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose Oral Formulation 6: Mixing with food powders Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.  (Please use freshly prepared in vivo formulations for optimal results.)

Preparing Stock Solutions		1 mg	5 mg	10 mg
	1 mM	0.2595 mL	1.2973 mL	2.5947 mL
	5 mM	0.0519 mL	0.2595 mL	0.5189 mL
	10 mM	0.0259 mL	0.1297 mL	0.2595 mL

*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.