Expression and function of bradykinin receptors in microglia

Mami Noda, Yukihiro Kariura, Taiju Amano, Yoshimasa Manago, Kaori Nishikawa, Shunsuke Aoki, Keiji Wada

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51 Citations (Scopus)


Expression of bradykinin (BK) receptors and their cellular function were investigated in microglia. Microglial cells were isolated from mixed cultures of cerebrocortical cells from postnatal day 3 Wistar rats. Reverse transcription-PCR (RT-PCR) showed that rat primary microglia express mRNAs for the type 2 bradykinin (B2) receptor subtype but not the type 1 (B1) receptor subtype under our experimental condition. However, the expression of B1 receptor was greatly up-regulated after the treatment of microglia with BK for 24 hours. The expression of B2 receptor in microglia was further confirmed by immunocytochemistry. Membrane currents were measured using whole-cell recording under voltage-clamp conditions. In 14% of patched cells (12/85 cells), BK (100-200 nM) induced an outward current at the holding potential of -20 mV, with oscillations in 2 cases. The BK-induced outward current was transient and desensitized rapidly. TEA inhibited the BK-induced outward current in a dose-dependent manner. These results suggest that microglia express B2 receptors and presumably increase the intracellular Ca2+ concentration via inositol trisphosphate with the subsequent activation of Ca2+-dependent K+ channels. Our data provide the first evidence that microglia express functional BK receptors and support the idea that microglia play an important role in CNS inflammatory responses.

Original languageEnglish
Pages (from-to)1573-1581
Number of pages9
JournalLife Sciences
Issue number14
Publication statusPublished - Feb 21 2003

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Pharmacology, Toxicology and Pharmaceutics(all)

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