Urocortinergic neurons respond in a differentiated manner to various acute stressors in the Edinger-Westphal nucleus in the rat.
Corticotropin-releasing factor (CRF) was implicated as being a major contributor to the neurochemically mediated central regulation of stress response; however, an increasing body of evidence suggests that, besides CRF, other members of this neuropeptide family, such as urocortin (Ucn), may also play a role in modifying the efferent components of immune, endocrine, and behavioral responses to stress. Ucn's distribution in the rat brain has been demonstrated, with the most abundant Ucn-immunoreactive perikarya present in the Edinger-Westphal nucleus (E-WN). Acute pain and immobilization stresses recruit E-WN neurons, however, the activation pattern of E-WN Ucn neurons in response to various acute systemic and neurogenic challenges has not been compared in a single study. We therefore combined quantitative Fos imaging as a marker for neuronal activation with urocortin immunohistochemistry to visualize neurons induced by intravenous lipopolysaccharide (LPS; 100 microg/kg), ether inhalation, restraint, hyperosmotic (1.5 M NaCl i.p.), and hypotensive hemorrhage challenges. Neurons in the E-WN responded with the strongest Fos induction to LPS, but ether and restraint stress also resulted in massive Fos immunoreactivity 2 hours after stress. Unexpectedly, hyperosmotic and hypotensive hemorrhage stresses did not induce urocortinergic perikarya in this brain area 2 hours poststress. This challenge-specific recruitment of E-WN neurons was independent of stress-induced adrenal response. The biological significance and the stress-specific activation of E-WN urocortinergic neurons will be discussed.
Gaszner
Balázs
B
Department of Anatomy, Medical Faculty, Pécs University and Neurohumoral Regulations Research Group of the Hungarian Academy of Sciences, H-7643 Pécs, Szigeti út 12, Hungary.
Csernus
Valér
V
Kozicz
Tamás
T
D000208:Acute Disease; D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000032:analysis / Q000096:biosynthesis*; D008297:Male; D009415:Nerve Net / Q000737:chemistry / Q000378:metabolism; D009474:Neurons / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013312:Stress, Physiological / Q000378:metabolism*; D054832:Urocortins
D054832:Urocortins; D003346:Corticotropin-Releasing Hormone