The Dual Role of the GABA(A) Receptor in Peripheral Inflammation and Neuroinflammation: A Study in Hyperammonemic Rats

Autores de CIPF

• Michele Malaguarnera

  Autor

• Tiziano Balzano

  Autor

• M Carmen Castro Quero

  Autor

• 

  Marta Llansola Gil

  Autor

• 

  Vicente Felipo Orts

  Autor

Grupos de Investigación

• Laboratorio de Neurobiología

  

  Jefe/a de Grupo

  Vicente Felipo Orts

Abstract

Cognitive and motor impairment in minimal hepatic encephalopathy (MHE) are mediated by neuroinflammation, which is induced by hyperammonemia and peripheral inflammation. GABAergic neurotransmission in the cerebellum is altered in rats with chronic hyperammonemia. The mechanisms by which hyperammonemia induces neuroinflammation remain unknown. We hypothesized that GABA(A) receptors can modulate cerebellar neuroinflammation. The GABA(A) antagonist bicuculline was administrated daily (i.p.) for four weeks in control and hyperammonemic rats. Its effects on peripheral inflammation and on neuroinflammation as well as glutamate and GABA neurotransmission in the cerebellum were assessed. In hyperammonemic rats, bicuculline decreases IL-6 and TNF alpha and increases IL-10 in the plasma, reduces astrocyte activation, induces the microglia M2 phenotype, and reduces IL-1 beta and TNF alpha in the cerebellum. However, in control rats, bicuculline increases IL-6 and decreases IL-10 plasma levels and induces microglial activation. Bicuculline restores the membrane expression of some glutamate and GABA transporters restoring the extracellular levels of GABA in hyperammonemic rats. Blocking GABA(A) receptors improves peripheral inflammation and cerebellar neuroinflammation, restoring neurotransmission in hyperammonemic rats, whereas it induces inflammation and neuroinflammation in controls. This suggests a complex interaction between GABAergic and immune systems. The modulation of GABA(A) receptors could be a suitable target for improving neuroinflammation in MHE.

Keywords

• bicuculline; cerebellum; astrocyte activation; microglia phenotype; cytokines; GABA and glutamate transporters; hepatic encephalopathy