Article date: September 2002
By: Abu Zaki, R Barrett‐Jolley in Volume 137, Issue 1, pages 87-97
We have used a range of in vitro electrophysiological techniques to investigate the mechanism of rapid cortisol neuromodulation of parvocellular neurones in the rat paraventricular nucleus.
In our study, we found that cortisol (10 μM) increased spontaneous action–current firing frequency to 193%. This effect was insensitive to the glucocorticoid intracellular‐receptor antagonist mifepristone.
Cortisol (0.1–10 μM) had no detectable effects on whole‐cell GABA current amplitudes, or GABAA single‐channel kinetics.
Cortisol (10 μM) inhibited whole‐cell potassium currents in parvocellular neurones by shifting the steady‐state activation curve by 14 mV to the right.
Additionally, in a cell line expressing both the glucocorticoid intracellular receptor and recombinant, fast inactivating potassium channels (hKv1.3), cortisol (1 and 10 μM) inhibited potassium currents by shifting their steady‐state activation curves to the right by 12 mV (10 μM cortisol). This effect was also insensitive to the cortisol antagonist, mifepristone.
These data suggest that inhibition of voltage‐gated potassium channels may contribute to the rapid neuromodulatory effects of cortisol, possibly by direct interaction with the ion channel itself.
We have used a range of in vitro electrophysiological techniques to investigate the mechanism of rapid cortisol neuromodulation of parvocellular neurones in the rat paraventricular nucleus.
In our study, we found that cortisol (10 μM) increased spontaneous action–current firing frequency to 193%. This effect was insensitive to the glucocorticoid intracellular‐receptor antagonist mifepristone.
Cortisol (0.1–10 μM) had no detectable effects on whole‐cell GABA current amplitudes, or GABAA single‐channel kinetics.
Cortisol (10 μM) inhibited whole‐cell potassium currents in parvocellular neurones by shifting the steady‐state activation curve by 14 mV to the right.
Additionally, in a cell line expressing both the glucocorticoid intracellular receptor and recombinant, fast inactivating potassium channels (hKv1.3), cortisol (1 and 10 μM) inhibited potassium currents by shifting their steady‐state activation curves to the right by 12 mV (10 μM cortisol). This effect was also insensitive to the cortisol antagonist, mifepristone.
These data suggest that inhibition of voltage‐gated potassium channels may contribute to the rapid neuromodulatory effects of cortisol, possibly by direct interaction with the ion channel itself.
British Journal of Pharmacology (2002) 137, 87–97. doi:10.1038/sj.bjp.0704832
DOI: 10.1038/sj.bjp.0704832
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