Localization of interleukin-18 and its receptor in somatotrophs of the bovine anterior pituitary gland.
A pro-inflammatory cytokine, interleukin 18 (IL-18), induces intracellular expression of IL-1 and the release of IL-6. IL-1 and IL-6 has been detected in anterior pituitary cells, suggesting that IL-18 is produced in anterior pituitary cells and may serve to aid immuno-endocrine regulation. In the present study, we addressed this hypothesis by investigating the intracellular localization of IL-18 and its receptor in bovine anterior pituitary gland. IL-18 mRNA and its protein were detected in the anterior pituitary gland by RT-PCR and Western blotting. In situ hybridization showed that IL-18 mRNA was expressed in the anterior pituitary cells. Immunohistochemistry of IL-18 and specific hormones revealed the presence of IL-18 in somatotrophs. Furthermore, the expression of GH mRNA in IL-18 immunoreactive cells was confirmed by immuno-laser microdissection. These results first demonstrated that somatotrophs produced IL-18. Subsequently, the distribution of the IL-18 receptor alpha (IL-18Ralpha) was investigated in order to understand IL-18 signaling among the anterior pituitary cells. Bovine IL-18Ralpha cDNA was partially sequenced and detected in the anterior pituitary gland by RT-PCR. Immunohistochemistry of IL-18Ralpha, IL-18 and GH showed that IL-18Ralpha was co-localized in IL-18 immunoreactive cells or somatotrophs. These data suggest that IL-18 acts on somatotrophs as an immuno-endocrine mediator through the autocrine pathway.
Laboratory of Functional Morphology, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, 981-8555, Sendai, Japan.
Yasuhiro
Y
Nagai
Tomonori
T
Nochi
Kouichi
K
Watanabe
Keisuke
K
Watanabe
Hisashi
H
Aso
Haruki
H
Kitazawa
Masatoshi
M
Matsuzaki
Shyuichi
S
Ohwada
Takahiro
T
Yamaguchi
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D004247:DNA / Q000235:genetics; D005260:Female; D015151:Immunoblotting; D020382:Interleukin-18 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D010903:Pituitary Gland, Anterior / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D018123:Receptors, Interleukin / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D053724:Receptors, Interleukin-18; D020133:Reverse Transcriptase Polymerase Chain Reaction
D020382:Interleukin-18; D012333:RNA, Messenger; D018123:Receptors, Interleukin; D053724:Receptors, Interleukin-18; D004247:DNA