Urocortin (Urocortin1: Ucn1) is first identified in rat 1), and later in human2) and mouse3). It is the second mammalian member of the CRF family. Rat and mouse Ucn1 have the same amino acid sequence and display 95% structure homology to human Ucn1, 45% to CRF and 63% to urotensin.
In the rat, Ucn1 immunoreactivity (IR) was shown to distribute widely in central nervous system, endocrine organs, and digestive system and its concentration was highest in pituitary (11 pmol/g, w.w.) 4). Koziez, Yanaihara et al. used a polyclonal antibody against rat Ucn1 to define the distribution of Ucn1-IR in rat central nervous system and found a large number of neurons with Ucn1-IR in rat brain 5).
Synthetic human Ucn1 binds with high affinity to CRF receptor type 1(CRFR1), 2 alpha(CRFR2α) and 2 beta (CRFR2β). CRFR1 and CRFR2 have been shown to link to the development of stress-related disorders, such as mood and eating disorders. CRFR1 is expressed predominantly in the brain and pituitary, whereas CRFR2 expression is limited to particular brain areas and to some peripheral organs 6). Data were also presented supporting the hypothesis that this peptide is the endogenous ligand for the CRFR2. 5)
Synthetic human Ucn1 stimulates cAMP accumulation in cells stably transfected with those receptors and acts in vitro to release ACTH from dispersed rat anterior pituitary cells. In addition, the CRF-binding protein binds human Ucn1 with high affinity and can prevent Ucn1-stimulated ACTH secretion in vitro2). Ucn1 was suggested to play important roles in various tissues in normal rats, but shown not to behave as a hypothalamic hypophysiotropic factor in mediating adrenocorticotropin secretin in adrenalectomized rats 4). Ucn1 has been implicated in various endocrine responses, such as blood pressure regulation, as well as in higher cognitive functions 5).
Synthetic human Ucn1 also stimulates plasma ACTH, cortisol and atrial natriuretic peptide (ANP) secretin and suppresses plasma ghrelin in healthy male volunteers7). In the human, plasma Ucn1 is elevated in heart failure, especially in its early stages. This fact may useful in the diagnosis of early heart failure 8).
We have already developed mouse urocortin 2 (Ucn2) EIA kit (YK190), rat urocortin 2 (Ucn2) EIA kit (YK191) and mouse/rat urocortin 3 (Ucn3) EIA kit (YK200). This time, as a part of tools for urocortin research, our laboratory developed mouse/rat Ucn1 EIA kit (YK210), which is highly specific for mouse/rat Ucn1 with almost no crossreaction with Ucn2 (mouse), Ucn2 (rat), Ucn3 (mouse, rat), ACTH (mouse, rat), ACTH (human) and CRF (mouse, rat, human). The kit can be used for measurement of Ucn1 in mouse/rat plasma or serum with high sensitivity. It will be a specifically useful tool for Ucn1 research.
<Reference>
1. Vázquez-Palacios G, Retana-Márquez S et al: Further definition of the effect of corticosterone on the sleep-wake pattern in the male rat. Pharmacol Biochem Behav 70:305-310, 2001
2. Goymann W, Möstl E and Gwinner E: Corticosterone metabolites can be measured noninvasively in excreta of European Stonechats (Saxicola torquata rubicola). The Auk 119:1167-1173. 2002
3. Hupe JM, James AC et al: Cortical feedback improves discrimination between figure and background by V1, V2 and V3 neurons.Nature 394:784-787, 1998
4. Kitaysky AS, Kitaiskaiya EV et al: Dietary restriction causes chronic elevation of corticosterone and enhances stress response in red-legged kittiwake chicks. J Comp Physiol B: Regulatory, Integrative and Comparative Physiology 171:701-709, 2001
5. Thelling O, Noel G et al: Stress hormone secretion and gut signal transducer (STAT) proteins after burn injury in rats. Shock 16:393-397, 2001
6. National Committee for Clinical Laboratory Standards Evaluation Protocols, SC1 (1989), Vallanova, PA: NCCLS
