Ketamine reduces electrophysiological network activity in cortical neuron cultures already at sub-micromolar concentrations - Impact on TrkB-ERK1/2 signaling.
A Ahtiainen, I Annala, M Rosenholm, S Kohtala, J Hyttinen, J M A Tanskanen, T Rantamäki
Neuropharmacology May 15, 2023 DOI: 10.1016/j.neuropharm.2023.109481 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | In vitro experimental study Peer reviewed |
|---|---|
| Population | Rat cortical neuron cultures at 14 days in vitro |
| Interventions | Ketamine BDNF Carbachol Diazepam |
| Dose | 500 nM, 10 μM |
| Duration | 14 days in vitro |
| Topics | Ketamine Esketamine |
| Keywords | Cortical neuron culture Extracellular electrophysiology Microelectrode array Neuronal activity Trkb phosphorylation |
| Key findings | Sub-micromolar ketamine did not increase neuronal network activity or TrkB-ERK1/2 phosphorylation in rat cortical cultures that responded strongly to BDNF; instead spiking decreased at 500 nM. High-concentration ketamine (10 μM) strongly reduced spiking, bursting, and burst duration, accompanied by decreased ERK1/2 phosphorylation but unchanged TrkB. |
Abstract
The dissociative anesthetic ketamine regulates cortical activity in a dose-dependent manner. Subanesthetic-dose ketamine has paradoxical excitatory effects which is proposed to facilitate brain-derived neurotrophic factor (BDNF) (a ligand of tropomyosin receptor kinase B, TrkB) signaling, and activation of extracellular signal-regulated kinase 1/2 (ERK1/2). Previous data suggests that ketamine, at sub-micromolar concentrations, induces glutamatergic activity, BDNF release, and activation of ERK1/2 also on primary cortical neurons. We combined western blot analysis with multiwell-microelectrode array (mw-MEA) measurements to examine ketamine's concentration-dependent effects on network-level electrophysiological responses and TrkB-ERK1/2 phosphorylation in rat cortical cultures at 14 days in vitro. Ketamine did not cause an increase in neuronal network activity at sub-micromolar concentrations, but instead a decrease in spiking that was evident already at 500 nM concentration. TrkB phosphorylation was unaffected by the low concentrations, although BDNF elicited prominent phosphorylation response. High concentration of ketamine (10 μM) strongly reduced spiking, bursting and burst duration, which was accompanied with decreased phosphorylation of ERK1/2 but not TrkB. Notably, robust increases in spiking and bursting activity could be produced with carbachol, while it did not affect phosphorylation of TrkB or ERK1/2. Diazepam abolished neuronal activity, which was accompanied by reduced ERK1/2 phosphorylation without change on TrkB. In conclusion, sub-micromolar ketamine concentrations did not cause an increase in neuronal network activity or TrkB-ERK1/2 phosphorylation in cortical neuron cultures that readily respond to exogenously applied BDNF. Instead, pharmacological inhibition of network activity can be readily observed with high concentration of ketamine and it is associated with reduced ERK1/2 phosphorylation.