Activation of the alpha 7 Nicotinic Acetylcholine Receptor Prevents against Microglial-Induced Inflammation and Insulin Resistance in Hypothalamic Neuronal Cells

Neuronal hypothalamic insulin resistance is implicated in energy balance dysregulation and contributes to the pathogenesis of several neurodegenerative diseases. Its development has been intimately associated with a neuroinflammatory process mainly orchestrated by activated microglial cells. In this regard, our study aimed to investigate a target that is highly expressed in the hypothalamus and involved in the regulation of the inflammatory process, but still poorly investigated within the context of neuronal insulin resistance: the alpha 7 nicotinic acetylcholine receptor (alpha 7nAchR). Herein, we show that mHypoA-2/29 neurons exposed to pro-inflammatory microglial conditioned medium (MCM) showed higher expression of the pro-inflammatory cytokines IL-6, IL-1 beta, and TNF-alpha, in addition to developing insulin resistance. Activation of alpha 7nAchR with the selective agonist PNU-282987 prevented microglial-induced inflammation by inhibiting NF-kappa B nuclear translocation and increasing IL-10 and tristetraprolin (TTP) gene expression. The anti-inflammatory role of alpha 7nAchR was also accompanied by an improvement in insulin sensitivity and lower activation of neurodegeneration-related markers, such as GSK3 and tau. In conclusion, we show that activation of alpha 7nAchR anti-inflammatory signaling in hypothalamic neurons exerts neuroprotective effects and prevents the development of insulin resistance induced by pro-inflammatory mediators secreted by microglial cells.