Background and purpose
Dysfunction of the prefrontal cortex (PFC) is involved in the cognitive deficits in neuropsychiatric diseases, such as schizophrenia, characterized by deficient neurotransmission known as NMDA receptor hypofrontality. Thus, enhancing prefrontal activity may alleviate hypofrontality-induced cognitive deficits. To test this hypothesis, we investigated the effect of forebrain-specific suppression or pharmacological inhibition of native Kv 7/KCNQ/M-current on glutamatergic hypofrontality induced by the NMDA receptor antagonist MK-801. Experimental approach: The forebrain-specific inhibition of native M-current was generated by transgenic expression, in mice, of a dominant-negative pore mutant G279S of Kv 7.2/KCNQ2 channels that suppresses channel function. A mouse model of cognitive impairment was established by single i.p. injection of 0.1 mg·kg-1 MK-801. Mouse models of prepulse inhibition (PPI) of acoustic startle reflex and Y-maze spontaneous alternation test were used for evaluation of cognitive behaviour. Hippocampal brain slice recordings of LTP were used to assess synaptic plasticity. Hippocampus and cortex were dissected for detecting protein expression using western blot analysis. Key
Purpose
Dysfunction of the prefrontal cortex (PFC) is involved in the cognitive deficits in neuropsychiatric diseases, such as schizophrenia, characterized by deficient neurotransmission known as NMDA receptor hypofrontality. Thus, enhancing prefrontal activity may alleviate hypofrontality-induced cognitive deficits. To test this hypothesis, we investigated the effect of forebrain-specific suppression or pharmacological inhibition of native Kv 7/KCNQ/M-current on glutamatergic hypofrontality induced by the NMDA receptor antagonist MK-801. Experimental approach: The forebrain-specific inhibition of native M-current was generated by transgenic expression, in mice, of a dominant-negative pore mutant G279S of Kv 7.2/KCNQ2 channels that suppresses channel function. A mouse model of cognitive impairment was established by single i.p. injection of 0.1 mg·kg-1 MK-801. Mouse models of prepulse inhibition (PPI) of acoustic startle reflex and Y-maze spontaneous alternation test were used for evaluation of cognitive behaviour. Hippocampal brain slice recordings of LTP were used to assess synaptic plasticity. Hippocampus and cortex were dissected for detecting protein expression using western blot analysis. Key
Results
Genetic suppression of Kv 7 channel function in the forebrain or pharmacological inhibition of Kv 7 channels by the specific blocker XE991 enhanced PPI and also alleviated MK-801 induced cognitive decline. XE991 also attenuated MK-801-induced LTP deficits and increased basal synaptic transmissions. Western blot analysis revealed that inhibiting Kv 7 channels resulted in elevation of pAkt1 and pGSK-3β expressions in both hippocampus and cortex. Conclusions and implications: Both genetic and pharmacological inhibition of Kv 7 channels alleviated PPI and cognitive deficits. Mechanistically, inhibition of Kv 7 channels promotes synaptic transmission and activates Akt1/GSK-3β signalling.