The modulatory effect of motor cortex astrocytes on diabetic neuropathic pain.

Diabetic neuropathic pain (DNP) is a common complication of diabetes characterized by persistent pain. Emerging evidence links astrocytes to mechanical nociceptive processing, and the motor cortex (MCx) is a cerebral cortex region that is known to play a key role in pain regulation. However, the association between MCx astrocytes and DNP pathogenesis remains largely unexplored. Here, we studied this association using designer receptors exclusively activated by designer drugs (DREADDs) to specifically manipulate MCx astrocytes. We proved that the selective inhibition of MCx astrocytes reduced DNP in streptozocin (STZ)-induced DNP models and discovered a potential mechanism by which astrocytes release cytokines, including tumor necrosis factor alpha (TNF-α) and interleukin 1 beta (IL-1β), to increase neuronal activation in the MCx, thereby regulating pain. Together, these results demonstrate a pivotal role for MCx astrocytes in DNP pathogenesis and provide new insight into DNP treatment strategies. Significance Statement Astrocytes are critical for maintaining CNS homeostasis. In recent years, astrocytes have been demonstrated to play roles in pain signaling modulation and neuropathic pain maintenance, with studies showing that they inhibit pain transmission at the spinal level. This work suggests that astrocytes also modulate pain at the supraspinal level. Indeed, we show that chemogenetically manipulated MCx astrocytes affect the mechanical withdrawal thresholds of rats and elucidate a potential mechanism by which astrocytes release inflammatory mediators to increase neuronal activation in the MCx, thereby regulating pain. Together, our data support that inhibition of astrocytes in the MCx region might have broad prospects for diabetic neuropathic pain treatment.