PT  - JOURNAL ARTICLE
AU  - Farhan Ali
AU  - Danielle M. Gerhard
AU  - Katherine Sweasy
AU  - Santosh Pothula
AU  - Christopher Pittenger
AU  - Ronald S. Duman
AU  - Alex C. Kwan
TI  - Ketamine disinhibits dendrites and enhances calcium signals in prefrontal dendritic spines
AID  - 10.1101/659292
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 659292
4099  - http://biorxiv.org/content/early/2019/08/23/659292.short
4100  - http://biorxiv.org/content/early/2019/08/23/659292.full
AB  - A subanesthetic dose of ketamine causes acute psychotomimetic symptoms and then more sustained antidepressant effects. A key targeted brain region is the prefrontal cortex, and the prevailing disinhibition hypothesis posits that N-methyl-d-aspartate receptor (NMDAR) antagonists such as ketamine may act preferentially on GABAergic neurons. However, cortical GABAergic neurons are heterogeneous. In particular, somatostatin-expressing (SST) interneurons selectively inhibit dendrites and regulate synaptic inputs, yet their response to systemic NMDAR antagonism is unknown. Here, we report that administration of ketamine acutely suppresses the activity of SST interneurons in the medial prefrontal cortex of the awake mouse. The deficient dendritic inhibition leads to greater synaptically evoked calcium transients in the apical dendritic spines of pyramidal neurons. By manipulating NMDAR signaling via GluN2B knockdown, we show that ketamine’s actions on the dendritic inhibitory mechanism has ramifications for frontal cortex-dependent behaviors and cortico-cortical connectivity. Collectively, these results demonstrate dendritic disinhibition and elevated calcium levels in dendritic spines as important local-circuit alterations driven by the administration of subanesthetic ketamine.