Altered GABAergic inhibition in CA1 pyramidal neurons modifies despair-like behavior in mice

Abstract

Despair is a common human feeling characterized by the loss of hope and is a core symptom of depressive disorders. However, little is known regarding neural circuits mediating despair and their modulation by antidepressants. Here we show that alterations in inhibitory synaptic transmission in the hippocampus affect behavioral despair in mice. Reduced interneuron density, knockdown of GABAA receptor gamma 2 subunit gene (Gabrg2) or DREADD-mediated suppression of interneuron activity resulted in disinhibition of CA1 neurons and anti-despair-like behaviors in mice. Similarly, a low dose of pentylenetetrazol, a GABAAR antagonist, induced transient anti-despair-like behaviors, with rapid eukaryotic elongation factor 2 (eEF2) activation in the hippocampus. Conversely, pharmacological and chemogenetic potentiation of GABAergic transmission in CA1 neurons induced despair-like behaviors. The antidepressant ketamine rapidly increased c-Fos expression in CA1 neurons and induced anti-despair-like behaviors. These results suggest that the enhanced hippocampal CA1 neuron activity induces anti-despair-like behaviors and contributes to the antidepressant effects of ketamine.