Neurons of the superior nucleus of the medial habenula and ependymal cells express IL-18 in rat CNS.
The habenular-interpeduncular pathway is involved in the modulation of several functions including neuroendocrine and stress responses. Interleukin-18 (IL-18) is a pro-inflammatory cytokine predominantly studied as a modulator of immune functions and also produced in the adrenal cortex following activation of the hypothalamic-pituitary-adrenal axis. In the central nervous system, IL-18 was demonstrated to induce sleep and to influence long-term potentiation and was proposed to mediate local inflammatory reactions. The present study investigated the localization of IL-18 and its expression following either acute or chronic restraint stress in the brain of adult male Wistar rats. Using immunocytochemistry and in situ hybridization we report the unprecedented localization of IL-18 in the neurons of the superior part of the medial habenula (MHbS), their projections to the interpenducular nucleus and its expression in the ependymal cells surrounding the third and the lateral ventricles. In addition, acute (2 h) or chronic (6 h/day for 3 weeks) restraint stress induced a strong elevation of IL-18 immunostaining in the MHbS but not in ependymal cells. The present data suggest that IL-18 may participate in the modulation of stress responses in the MHbS. They also suggest that ependymal cells may be the source of IL-18 previously reported in the cerebrospinal fluid (CSF). The role of IL-18 in the ependyma and the CSF remains to be elucidated.
Sugama
Shuei
S
Harold L Dorris Neurological Research Center, Department of Neuropharmacology, The Scripps Research Institute, 10550 North Torrey Pines Road, SR307, La Jolla, CA 92037, USA.
Cho
Byung Pil
BP
Baker
Harriet
H
Joh
Tong H
TH
Lucero
Jacinta
J
Conti
Bruno
B
D000818:Animals; D002555:Cerebrospinal Fluid / Q000276:immunology / Q000378:metabolism; D004525:Efferent Pathways / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D004805:Ependyma / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D019262:Habenula / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D007150:Immunohistochemistry; D020382:Interleukin-18 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D020547:Lateral Ventricles / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D008297:Male; D015213:Neuroimmunomodulation / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013312:Stress, Physiological / Q000134:cerebrospinal fluid / Q000276:immunology* / Q000378:metabolism; D020542:Third Ventricle / Q000166:cytology / Q000276:immunology / Q000378:metabolism
D020382:Interleukin-18; D012333:RNA, Messenger