【Introduction】 Resident macrophages within gastrointestinal muscularis layer (MMφ) are located near sympathetic nerves. However, the role of adrenergic signaling in regulating MMφ activation during inflammation remains unclear. This study aims to elucidate the the role of adrenergic receptors in MMφ activation.
【Methods】 The expression of adrenergic receptors mRNA in isolated MMφ was examined using RT-PCR. The J774.1 macrophage cell line was treated with LPS for 24 hours, either in the presence of adrenergic receptor agonists or antagonists. The production of nitric oxide (NO) was evaluated using the Griess method as an indicator for MMφ activation.
【Results】 MMφ expressed mRNA for α₁, α₂, β₁, and β₂ adrenergic receptors. Stimulation of J774.1 with LPS increased NO production. This increase in NO production was significantly reduced by both dobutamine and clenbuterol. Treatment with noradrenaline significantly decreased the LPS-induced NO production. Propranolol suppressed the inhibitory effect of noradrenaline on NO production. Additionally, both atenolol and butoxamine suppressed the noradrenaline-induced inhibitory effect on NO production.
【Conclusion】 Our results suggest that noradrenaline released from sympathetic nerves might suppress the inflammatory activation of MMφ via β₁ and β₂ adrenergic receptors.