Stimulation of nuclear receptor REV-ERBs suppresses production of pronociceptive molecules in cultured spinal astrocytes and ameliorates mechanical hypersensitivity of inflammatory and neuropathic pain of mice.

The orphan nuclear receptors REV-ERBα and REV-ERBβ (REV-ERBs) are crucial in the regulation of inflammatory-related gene transcription in astroglioma cells, but their role in nociceptive transduction has yet to be elaborated. Spinal dorsal horn astrocytes contribute to the maintenance of chronic pain. Treatment of cultured spinal astrocytes with specific REV-ERBs agonists SR9009 or GSK4112 significantly prevented lipopolysaccharide (LPS)-induced mRNA upregulation of pronociceptive molecules interleukin-1β (IL-1β) mRNA, interleukin-6 (IL-6) mRNA and matrix metalloprotease-9 (MMP-9) mRNA, but not CCL2 mRNA expression.

Downregulation of the spinal dorsal horn clock gene Per1 expression leads to mechanical hypersensitivity via c-jun N-terminal kinase and CCL2 production in mice.

Disturbances of circadian rhythm and dysregulation of clock gene expression are involved in the induction of various neurological disorder states, including chronic pain. However, the relationship between the CNS circadian-clock gene system and nociception remains poorly defined. Significant circadian oscillations of Period (Per1, Per2), Bmal1 and Cryptochrome 1 (Cry1) mRNA expression have been observed in the lumbar spinal dorsal horn of naïve mice.

Stimulation of nuclear receptor REV-ERBs regulates tumor necrosis factor-induced expression of proinflammatory molecules in C6 astroglial cells.

Under physiological conditions, astrocytes maintain homeostasis in the CNS. Following inflammation and injury to the CNS, however, activated astrocytes produce neurotoxic molecules such as cytokines and chemokines, amplifying the initial molecular-cellular events evoked by inflammation and injury. Nuclear receptors REV-ERBα and REV-ERBβ (REV-ERBs) are crucial in the regulation of inflammation- and metabolism-related gene transcription.

The induction of Per1 expression by the combined treatment with glutamate, 5-hydroxytriptamine and dopamine initiates a ripple effect on Bmal1 and Cry1 mRNA expression via the ERK signaling pathway in cultured rat spinal astrocytes.

Clock genes contribute to the regulation of spinal cord astrocytic function. Although it was previously found that noradrenaline has a pivotal role in the regulation of clock genes expression in cultured rat spinal astrocytes, it is still unknown whether other neurotransmitters might affect clock gene expression. Thus, the effect of spinal neurotransmitters glutamate (Glu), 5-hydroxytriptamine (5-HT) and dopamine (DA) on clock genes expression was examined in cultured rat spinal astrocytes.