3 beta-hydroxysteroid dehydrogenase/delta 5-->4-isomerase type 1

Phorbol 12-myristate 13-acetate (PMA) is a natural phorbol ester that acts as an activator of PKC, SphK, and NF-κB, and is commonly used to induce differentiation of THP-1 cells and establish dermatitis models.

L-Arginine (L-Arg) is a substrate of endothelial nitric oxide synthase (eNOS). L-Arginine is transported to vascular smooth muscle cells via a family of cationic amino acid transporters and is metabolized to nitric oxide, polyamines, or L-proline. L-Arginine is a potent vasodilator and can be used to induce experimental acute pancreatitis.

Amiodarone is an antiarrhythmic compound that inhibits ATP-sensitive potassium channels (IC₅₀ = 19.1 μM) and can induce pulmonary toxicity. It has shown some antiviral activity in diseases caused by SARS-CoV-2 and is commonly used to establish animal models of pulmonary fibrosis.

Bicuculline is an alkaloid extracted from Corydalis decumbens, acting as a competitive antagonist of the neurotransmitter GABAA receptor (IC50 = 2 μM). It also blocks Ca2+-activated potassium (SK) channels and inhibits slow afterhyperpolarization (slow AHP). Bicuculline has anticonvulsant effects and is commonly used to establish mouse seizure models.

Scopolamine is a high-affinity (nanomolar level) muscarinic receptor antagonist that can reversibly inhibit 5-HT₃ receptor responses (IC₅₀ = 2.09 μM). It is commonly used to induce animal models of Alzheimer's disease or memory impairment.

Glycerol is an important component of triglycerides (fats and oils) and phospholipids. It is widely used in the food industry as a sweetener, humectant, and in pharmaceutical formulations. Additionally, glycerol is used in sample preparation and gel formation for polyacrylamide gel electrophoresis and can be employed to induce acute kidney injury models.

Doxycycline calcium is an orally active tetracycline antibiotic that also functions as a broad-spectrum matrix metalloproteinase (MMP) inhibitor, exhibiting antibacterial and anti-tumor cell proliferation activities, and is commonly used to induce gene expression in ON-OFF systems.