mGluR1/IP3/ERK signaling pathway regulates vestibular compensation in ON UBCs of the cerebellar flocculus

Aims: To investigate the role of mGluR1 alpha in cerebellar unipolar brush cells (UBC) in mediating vestibular compensation (VC), using mGluR1 alpha agonist and antagonist to modulate ON UBC neurons, and explore the mGluR1/IP3/extracellular signal-regulated kinase (ERK) signaling pathway.Methods: First, AAV virus that knockdown ON UBC (mGluR1 alpha) were injected into cerebellar UBC by stereotactic, and verified by immunofluorescence and western blot. The effect on VC was evaluated after unilateral labyrinthectomy (UL). Second, saline, (RS)-3,5-dihydroxyphenylglycine (DHPG), and LY367385 were injected into tubes implanted in rats at different time points after UL separately. The effect on ON UBC neuron activity was evaluated by immunofluorescence. Then, Phosphoinositide (PI) and p-ERK1/2 levels of mGluR1 alpha were analyzed by ELISA after UL. The protein levels of p-ERK and total ERK were verified by western blot. In addition, the effect of mGluR1 alpha activation or inhibition on VC-related behavior was observed.Results: mGluR1 alpha knockdown induced VC phenotypes. DHPG increased ON UBC activity, while LY367385 reduced ON UBC activity. DHPG group showed an increase in PI and p-ERK1/2 levels, while LY367385 group showed a decrease in PI and p-ERK1/2 levels in cerebellar UBC of rats. The western blot results of p-ERK and total ERK confirm and support the observations. DHPG alleviated VC-related behavior phenotypes, while LY367385 exacerbated vestibular decompensation-like behavior induced by UL.Conclusion: mGluR1 alpha activity in cerebellar ON UBC is crucial for mediating VC through the mGluR1/IP3/ERK signaling pathway, which affects ON UBC neuron activity and contributes to the pathogenesis of VC.