Current Molecular Pharmacology - Volume 11, Issue 1, 2018

Background: Dysregulated stress neurocircuits, caused by genetic and/or environmental changes, underlie the development of many neuropsychiatric disorders. Corticotropin-releasing factor (CRF) is the major physiological activator of the hypothalamic-pituitary-adrenal (HPA) axis and consequently a primary regulator of the mammalian stress response. Together with its three family members, urocortins (UCNs) 1, 2, and 3, CRF integrates the neuroendocrine, autonomic, metabolic and behavioral responses to stress by activating its cognate receptors CRFR1 and CRFR2. Objective: Here we review the past and current state of the CRF/CRFR field, ranging from pharmacological studies to genetic mouse models and virus-mediated manipulations. Results: Although it is well established that CRF/CRFR1 signaling mediates aversive responses, including anxiety and depression-like behaviors, a number of recent studies have challenged this viewpoint by revealing anxiolytic and appetitive properties of specific CRF/CRFR1 circuits. In contrast, the UCN/CRFR2 system is less well understood and may possibly also exert divergent functions on physiology and behavior depending on the brain region, underlying circuit, and/or experienced stress conditions. Conclusion: A plethora of available genetic tools, including conventional and conditional mouse mutants targeting CRF system components, has greatly advanced our understanding about the endogenous mechanisms underlying HPA system regulation and CRF/UCN-related neuronal circuits involved in stress-related behaviors. Yet, the detailed pathways and molecular mechanisms by which the CRF/UCN-system translates negative or positive stimuli into the final, integrated biological response are not completely understood. The utilization of future complementary methodologies, such as cell-type specific Cre-driver lines, viral and optogenetic tools will help to further dissect the function of genetically defined CRF/UCN neurocircuits in the context of adaptive and maladaptive stress responses.

Background: There has been a constant pursuit for development of newer therapies which can contribute to the relatively nascent field of cardioprotection in the setting of myocardial ischemiareperfusion injury. One novel cardioprotective agent among others, that has shown promising results in the limited number of research studies undertaken till now, is Urocortin. Urocortins are peptides belonging to the Corticotropin-Releasing Hormone family. Results: Acting through a variety of downstream mechanisms, urocortin has been shown to alter cellular metabolism and modulate the mechanism of cell death occurring as a result of ischemia-reperfusion injury. New evidence continues to accumulate in support of urocortin’s beneficial role in cytoprotection. Conclusion: We present here an updated review largely focused on the various mechanisms through which urocortin alters cellular metabolism, and discuss the clinical potential of urocortin’s cardioprotective ability in myocardial ischemia-reperfusion injury.

Background: The corticotropin releasing factor (CRF) family of neuropeptides, CRF and the Urocortins, and their receptors are present not only within the central nervous system but also in the periphery at various locations and at the sites of inflammation where they influence its progress in a complex local / paracrine manner. Objective and Methods: This review summarizes current knowledge regarding the regulation of inflammatory process by CRF family of neuropeptides and receptors with a special sight into their role in inflammatory pain and in chronic low grade inflammation that occurs in obesity. For this purpose, we searched for relevant peer-reviewed research articles using bibliographic databases. Results: The CRF neuropeptides are either produced locally, by components of the inflammatory response or they may reach the inflammation sites via postganglionic sympathetic and sensory afferent nerve transport. It now appears that most immune cells taking part in the inflammatory process express CRF receptor type 1 (CRF1R) and type 2 (CRF2R) and thus represent targets of CRF neuropeptides. Indeed, mast cells, monocytes / macrophages, neutrophils and other types of immune cells express both types of the CRF receptors. In addition to their role in the pathophysiology of inflammation, CRF and its receptors also exert modulatory effects on inflammatory pain. Finally, it now appears that the CRF system is also present in adipose tissue and may play a crucial role in the development of the chronic low grade inflammation, which is characteristic of obesity. Conclusion: The local effects of the CRF family of neuropeptides can be either pro- or antiinflammatory depending on concentration of each type of neuropeptide present and the ratio of the local expression of their receptors CRF1R and CRF2R.

Background: Corticotropin-releasing factor (CRF) pathways coordinate behavioral, endocrine, autonomic and visceral responses to stress. Convergent anatomical, molecular, pharmacological and functional experimental evidence supports a key role of brain CRF receptor (CRF-R) signaling in stress-related alterations of gastrointestinal functions. These include the inhibition of gastric acid secretion and gastric-small intestinal transit, stimulation of colonic enteric nervous system and secretorymotor function, increase intestinal permeability, and visceral hypersensitivity. Brain sites of CRF actions to alter gut motility encompass the paraventricular nucleus of the hypothalamus, locus coeruleus complex and the dorsal motor nucleus while those modulating visceral pain are localized in the hippocampus and central amygdala. Brain CRF actions are mediated through the autonomic nervous system (decreased gastric vagal and increased sacral parasympathetic and sympathetic activities). The activation of brain CRF-R2 subtype inhibits gastric motor function while CRF-R1 stimulates colonic secretomotor function and induces visceral hypersensitivity. CRF signaling is also located within the gut where CRF-R1 activates colonic myenteric neurons, mucosal cells secreting serotonin, mucus, prostaglandin E2, induces mast cell degranulation, enhances mucosal permeability and propulsive motor functions and induces visceral hyperalgesia in animals and humans. CRF-R1 antagonists prevent CRF- and stressrelated gut alterations in rodents while not influencing basal state. Discussion: These preclinical studies contrast with the limited clinical positive outcome of CRF-R1 antagonists to alleviate stress-sensitive functional bowel diseases such as irritable bowel syndrome. Conclusion: The translational potential of CRF-R1 antagonists in gut diseases will require additional studies directed to novel anti-CRF therapies and the neurobiology of brain-gut interactions under chronic stress.

Background: Hypothalamic corticotrophin-releasing hormone (CRH) has a key role in coordinating and controlling complex responses to stress, both systemically, by stimulating the expression of the pituitary POMC gene, and thus, resulting in increased production of ACTH and adrenal glucocorticoid release, and locally since CRH has been identified in several peripheral tissues. CRH seems to exert its effects through interaction with two known so far receptors, CRF1R and CRF2R. The mRNA and protein of CRH family of peptides and their receptors are expressed at several peripheral tissues including rodent and human skin. In addition to CRH, skin expresses POMC and its products, including ACTH while recent studies have shown the presence of glucocorticoids also in skin. Objective: This review aims to summarize the role of CRH in the physiology and pathophysiology of human and rodent skin. Results: It is clear that a) locally produced CRH is involved in the inflammatory process, b) CRH has been shown to stimulate angiogenesis in vivo and chemotaxis of endothelial cells in vitro, and c) CRH mRNA and peptide have been identified in skin. Conclusion: Based on the above we hypothesize that CRH plays a crucial role in several inflammatory pathologies of the skin as well as in cutaneous wound healing, which are all discussed in the present review.

Background: Corticotropin releasing hormone (CRH), the main peptide-mediator of stress, has been found in the female reproductive system. Objective: Herein, the role of CRH receptors in the female reproductive system is presented. Results: It is clear that CRH receptors are involved in the regulation of the hypothalamic-pituitaryovarian axis, while locally are associated with decidualization, embryonic implantation, early fetal development and triggering of parturition. Conclusion: Abnormal CRH signaling may contribute to obstetrical pathophysiology, such as preeclampsia, abnormal placenta invasion, endometrial growth retardation and preterm delivery.