Existence of functional β1- and β2-adrenergic receptors on microglia

✍ Scribed by Kenji F. Tanaka; Haruo Kashima; Hiromi Suzuki; Kenji Ono; Makoto Sawada

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 134 KB
• Volume: 70
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/jnr.10399

✦ Synopsis

Abstract

We examined the expression and function of β‐adrenergic receptor (β‐AR) subtypes in both isolated primary rat microglia and a rat microglial cell line. RT‐PCR analyses revealed that microglia expressed β~1~‐ and β~2~‐ARs but not β~3~‐ARs, whereas rat primary peritoneal macrophages expressed only β~2~‐ARs. Stimulation of β‐ARs on microglia by norepinephrine (NE) resulted in an increase in the level of intracellular cAMP and the subsequent expression of interleukin‐1β mRNA. These effects were prevented by propranolol. Similar results were obtained with other selective β~1~‐AR agonists and antagonists. β~2~‐ARs on microglia were also functional. It is possible that noradrenergic innervations participate in the control of microglial functions via β~1~‐ARs on microglia in the brain, because NE has high affinity for β~1~‐ and β~3~‐ARs but little or no affinity for β~2~‐ARs. It seems physiologically significant that microglia can be controlled by NE, which predominates over epinephrine in the brain, whereas macrophages in peripheral tissues can be controlled by epinephrine, which is at higher levels in peripheral tissues. © 2002 Wiley‐Liss, Inc.