TNF-? increases the intrinsic excitability of cerebellar Purkinje cells through elevating glutamate release in Bergmann Glia.

ABSTRACT: For decades, the glial function has been highlighted not only as the 'structural glue', but also as an 'active participant' in neural circuits. Here, we suggest that tumor necrosis factor ? (TNF-?), a key inflammatory cytokine, alters the neural activity of the cerebellar Purkinje cells (PCs) by facilitating gliotransmission in the juvenile male rat cerebellum. A bath application of TNF-? (100?ng/ml) in acute cerebellar slices elevates spiking activity of PCs with no alterations in the regularity of PC firings. Interestingly, the effect of TNF-? on the intrinsic excitability of PCs was abolished under a condition in which the type1 TNF receptor (TNFR1) in Bergmann glia (BG) was genetically suppressed by viral delivery of an adeno-associated virus (AAV) containing TNFR1-shRNA. In addition, we measured the concentration of glutamate derived from dissociated cerebellar cortical astrocyte cultures treated with TNF-? and observed a progressive increase of glutamate in a time-dependent manner. We hypothesised that TNF-?-induced elevation of glutamate from BGs enveloping the synaptic cleft may directly activate metabotropic glutamate receptor1 (mGluR1). Pharmacological inhibition of mGluR1, indeed, prevented the TNF-?-mediated elevation of the intrinsic excitability in PCs. Taken together, our study reveals that TNF-? triggers glutamate release in BG, thereby increasing the intrinsic excitability of cerebellar PCs in a mGluR1-dependent manner.

SUBMITTER: Shim HG 

PROVIDER: S-EPMC6072779 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature