Characterization of CRF1 receptor antagonists with differential peripheral vs central actions in CRF challenge in rats

Corticotropin-releasing factor receptor 1 (CRF-R1) antagonists: Promising agents to prevent visceral hypersensitivity in irritable bowel syndrome

Corticotropin-releasing factor (CRF) is a 41-amino acid polypeptide that coordinates the endocrine system, autonomic nervous system, immune system, and physiological behavior. CRF is a signaling regulator in the neuro-endocrine-immune (NEI) network that mediates visceral hypersensitivity. Rodent models to simulate changes in intestinal motility similar to those reported in the irritable bowel syndrome (IBS), demonstrate that the CRF receptor 1 (CRF-R1) mediates intestinal hypersensitivity under many conditions. However, the translation of preclinical studies into clinical trials has not been successful possibly due to the lack of sufficient understanding of the multiple variants of CRF-R1 and CRF-R1 antagonists. Investigating the sites of action of central and peripheral CRF is critical for accelerating the translation from preclinical to clinical studies.

Research on the Effects of the Chronic Treatment With Different Doses of Urocortin 2 in Heart Failure Rats

Corticotropin-releasing factor (CRF) receptor type 2 (CRF₂) exists in both cardiomyocytes and neurocytes. The purpose of this research was to explore if chronic treatment with urocortin 2 (UCN2), a CRF₂ receptor agonist, at different doses can improve prognosis and regulate the expression of CRF₂ receptor and calcium handling proteins without any adverse effects on behavior in heart failure. Heart failure was established in Sprague-Dawley rats and was confirmed by echocardiography. Heart failure rats were injected intraperitoneally with UCN2 (5, 10, or 20 µg·kg⁻¹·d⁻¹) for 30 days. Survival rate, cardiac function, expressions of cardiac CRF₂ receptor, RyR2, SERCA2, and hypothalamic and hippocampal c-FOS, CRF receptor type 1 (CRF₁) and CRF₂ receptor were determined. Behavior was evaluated by Morris Water-Maze and Open-Field tests. Results showed that chronic peripheral UCN2 treatment improved survival rate in a dose–response manner and increased cardiac function and expression of CRF₂ receptor and SERCA2 in heart failure, especially at the high dosage. Moreover, cellular-fos (c-FOS), CRF₁ receptor, and CRF₂ receptor expressions of both hypothalamic and hippocampal tissues were significantly increased in high dosage group. Furthermore, the behavior tests suggested that chronic UCN2 treatment did not exacerbate stress/anxiety-like behavior in HF. In conclusion, chronic peripheral treatment with UCN2 increases survival in a dose–response manner in heart failure rats without inducing stress/anxiety-like behavior.