Urocortin expression in the Edinger-Westphal nucleus is down-regulated in transgenic mice over-expressing neuronal corticotropin-releasing factor.
In recent years a large body of evidence has emerged linking chronic stress with increased vulnerability for depression and anxiety disorders. As corticotropin-releasing factor (CRF) is hypersecreted under these psychological conditions, we used our CRF-overexpressing (CRF-OE) mouse line to study underlying brain mechanisms possibly causing these disorders. Urocortin (Ucn), a recently discovered member of the CRF peptide family may play a role in the pathophysiology of stress-induced disorders. Stressors recruit Ucn-immunoreactive neurons in the Edinger-Westphal nucleus (E-WN), which is the major site of Ucn expression. Furthermore, E-WN Ucn mRNA levels are upregulated in CRF-deficient mice. Based on these findings, we hypothesized the down-regulation of E-WN Ucn in CRF-OE mice and consequently, altered responsiveness to stressful stimuli. Our results support this hypothesis as we found weaker immunohistochemical labeling with anti-Ucn and a six times weaker Ucn mRNA signal in E-WN in CRF-OE mice. Moreover, E-WN Ucn-expressing neurons mounted a response to acute challenge in CRF-OE mice too. From these results it is concluded that the CRF and E-WN Ucn neuronal systems work in concert in response to acute challenges, but are inversely regulated in their activities during chronic hyperactivity of the hypothalamo-pituitary-adrenal axis.
Kozicz
T
T
Department of Cellular Animal Physiology, Nijmegen Institute for Neurosciences, University of Nijmegen, Nijmegen, The Netherlands. tkozicz2000@yahoo.com
Korosi
A
A
Korsman
C
C
Tilburg-Ouwens
D
D
Groenink
L
L
Veening
J
J
van Der Gugten
J
J
Roubos
E
E
Olivier
B
B
D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000096:biosynthesis* / Q000235:genetics; D015536:Down-Regulation / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D008297:Male; D008636:Mesencephalon / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D009474:Neurons / Q000378:metabolism*; D013312:Stress, Physiological / Q000235:genetics / Q000378:metabolism; D054832:Urocortins
D054832:Urocortins; D003346:Corticotropin-Releasing Hormone