Melanocortin 2 Receptor Antagonists in Canine Cushing’s Disease: In Vitro Studies

Abstract Melanocortin 2 receptor antagonists in canine Cushing’s disease: vitro studies disease (CD), caused by an ACTH-secreting pituitary adenoma, is one of the most common endocrinopathies dogs. The current medical treatment options involve adrenocortical steroid synthesis inhibitors, but a selective targeted approach to block ACTH at its would be much more attractive. objective this study was preclinically investigate effect MC2R on hormone production, cell viability, and mRNA expression steroidogenic enzymes primary cultures from adrenal glands healthy Three different were used: CRN.1, CRN.2, CRN.4. Canine (n = 8) incubated with 50 nM for 24h, mimic CD. Thereafter, 10 (IC50) μM (maximal concentration) CRN.4 added. two concentrations established based preliminary studies. After 24 hours incubation, measured culture medium using liquid chromatography-mass spectrometry. RNA isolated cells RNeasy Microkit (Qiagen) subsequent real-time quantitative PCR analysis. Cell viability assessed after incubation alamarBlue™ Viability Reagent. All CRN compounds effectively inhibited cortisol concentrations, while leaving aldosterone unaffected. In incubations maximal concentration three compounds, decreased undetectable levels. levels StAR, CYP11A1, CYP17A1, HSD3B2, CYP21, CYP11B significantly conditions when compared ACTH-stimulated control. melanocortin accessory protein (MRAP) suppressed as well. not affected CNR.1 or CNR.4, slightly CRN.2. summary, useful model system drug testing. Incubation demonstrated potential CNR.4 new Future vivo dogs spontaneous CD are indicated.