Abstract
Rationale
The voltage-insensitive, small conductance calcium-activated potassium (SK) channel is a key regulator of neuronal depolarization, and is implicated in the pathophysiology of depressive disorders.
Objective
We ascertained whether the SK channel is impaired in the chronic unpredictable stress (CUS) model, and whether it can serve as a molecular target of antidepressant action.
Methods
We assessed the depressive-like behavioral phenotype of CUS-exposed rats, and
performed post-mortem SK channel binding and activity-dependent zif268 mRNA analyses on their brains. To begin an assessment of SK channel subtypes involved, we examined the effects of genetic and pharmacological inhibition of the SK3 channel using conditional knock-out mice and selective SK3 channel negative allosteric modulators (NAMs).
Results
We found that [ 125 I]apamin binding to SK channels is increased in the prefrontal cortex and decreased in the hippocampus, an effect that was associated with reciprocal levels of zif268 mRNA transcripts indicating abnormal regional cell activity in this model. We found that genetic and pharmacological manipulations significantly decreased immobility in the forced swim test without altering general locomotor activity, a hallmark of antidepressant-like activity.
Conclusions
Taken together, these findings link depression-related neural and behavioral
pathophysiology with abnormal SK channel functioning, and suggest that this can be reversed by the selective inhibition of SK3 channels.
The voltage-insensitive, small conductance calcium-activated potassium (SK) channel is a key regulator of neuronal depolarization, and is implicated in the pathophysiology of depressive disorders.
Objective
We ascertained whether the SK channel is impaired in the chronic unpredictable stress (CUS) model, and whether it can serve as a molecular target of antidepressant action.
Methods
We assessed the depressive-like behavioral phenotype of CUS-exposed rats, and
performed post-mortem SK channel binding and activity-dependent zif268 mRNA analyses on their brains. To begin an assessment of SK channel subtypes involved, we examined the effects of genetic and pharmacological inhibition of the SK3 channel using conditional knock-out mice and selective SK3 channel negative allosteric modulators (NAMs).
Results
We found that [ 125 I]apamin binding to SK channels is increased in the prefrontal cortex and decreased in the hippocampus, an effect that was associated with reciprocal levels of zif268 mRNA transcripts indicating abnormal regional cell activity in this model. We found that genetic and pharmacological manipulations significantly decreased immobility in the forced swim test without altering general locomotor activity, a hallmark of antidepressant-like activity.
Conclusions
Taken together, these findings link depression-related neural and behavioral
pathophysiology with abnormal SK channel functioning, and suggest that this can be reversed by the selective inhibition of SK3 channels.
| Original language | English |
|---|---|
| Pages (from-to) | 253-266 |
| Number of pages | 14 |
| Journal | Psychopharmacology |
| Volume | 239 |
| Issue number | 1 |
| Early online date | 4 Jan 2022 |
| DOIs | |
| Publication status | Published - Jan 2022 |
Bibliographical note
Funding and DisclosureThis research was supported by awards from the Neuroscience Catalyst program (Toronto) (FRB and JNN), the Canadian Institutes of Health Research (FRB and JN) and the National Science and Engineering Research Council of Canada (FRB). M.N. was additionally supported by a CAMH Discovery Fund Post-doctoral Fellowship.
Conflict of Interest: None declared.
Acknowledgments
We thank J. Li, U. Mumtaz, S. Khan, S. Sivaruban, M. Billyard, E. Hauck, D. Oleinichenko, Michael Coombs and Lucas Francis Fowler for technical assistance at different stages of the work.
Keywords
- small-conductance calcium-activated potassium (SK) channel
- antidepressant
- chronic unpredictable mild stress
- prefrontal cortex
- SK3 NAM