Localization of interleukin-18 and its receptor in somatotrophs of the bovine anterior pituitary gland

Cell Tissue Res. 2005 Dec;322(3):455-62. doi: 10.1007/s00441-005-0016-0. Epub 2005 Jul 7.

Abstract

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.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Cattle
  • DNA / genetics
  • Female
  • Immunoblotting
  • Interleukin-18 / biosynthesis
  • Interleukin-18 / genetics
  • Interleukin-18 / metabolism*
  • Male
  • Molecular Sequence Data
  • Pituitary Gland, Anterior / cytology
  • Pituitary Gland, Anterior / metabolism*
  • RNA, Messenger / biosynthesis
  • RNA, Messenger / genetics
  • Receptors, Interleukin / biosynthesis
  • Receptors, Interleukin / genetics
  • Receptors, Interleukin / metabolism*
  • Receptors, Interleukin-18
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • Interleukin-18
  • RNA, Messenger
  • Receptors, Interleukin
  • Receptors, Interleukin-18
  • DNA