Nitric Oxide Activates ATP-Sensitive Potassium Channels in Mammalian Sensory Neurons: Action by Direct S-Nitrosylation

Abstract

BackgroundATP-sensitive potassium (KATP) channels in neurons regulate excitability, neurotransmitter release and mediate protection from cell-death. Furthermore, activation of KATP channels is suppressed in DRG neurons after painful-like nerve injury. NO-dependent mechanisms modulate both KATP channels and participate in the pathophysiology and pharmacology of neuropathic pain. Therefore, we investigated NO modulation of KATP channels in control and axotomized DRG neurons.ResultsCell-attached and cell-free recordings of KATP currents in large DRG neurons from control rats (sham surgery, SS) revealed activation of KATP channels by NO exogenously released by the NO donor SNAP, through decreased sensitivity to [ATP]i.This NO-induced KATP channel activation was not altered in ganglia from animals that demonstrated sustained hyperalgesia-type response to nociceptive stimulation following spinal nerve ligation. However, baseline opening of KATP channels and their activation induced by metabolic inhibition was suppressed by axotomy. Failure to block the NO-mediated amplification of KATP currents with specific inhibitors of sGC and PKG indicated that the classical sGC/cGMP/PKG signaling pathway was not involved in the activation by SNAP. NO-induced activation of KATP channels remained intact in cell-free patches, was reversed by DTT, a thiol-reducing agent, and prevented by NEM, a thiol-alkylating agent. Other findings indicated that the mechanisms by which NO activates KATP channels involve direct S-nitrosylation of cysteine residues in the SUR1 subunit. Specifically, current through recombinant wild-type SUR1/Kir6.2 channels expressed in COS7 cells was activated by NO, but channels formed only from truncated isoform Kir6.2 subunits without SUR1 subunits were insensitive to NO. Further, mutagenesis of SUR1 indicated that NO-induced KATP channel activation involves interaction of NO with residues in the NBD1 of the SUR1 subunit.ConclusionNO activates KATP channels in large DRG neurons via direct S-nitrosylation of cysteine residues in the SUR1 subunit. The capacity of NO to activate KATP channels via this mechanism remains intact even after spinal nerve ligation, thus providing opportunities for selective pharmacological enhancement of KATP current even after decrease of this current by painful-like nerve injury.

Morphine peripheral analgesia depends on activation of the PI3Kγ/AKT/nNOS/NO/K ATP signaling pathway

“…5E). These results corroborate the following findings: (i) the up-regulation of K ATP by NO was recently shown in primary sensitive neurons (24); (ii) in vivo NO donor-reduced, PGE 2 -induced hypernociception was prevented by treatment with glibenclamide (25); and (iii) intratecal treatment of rats with ODN antisenses against Kir6.2 and SUR1, two different subunits of K ATP that are expressed by DRG neurons (26), prevented morphine and NO-donor antinociceptive effects (Fig. S7 A and B).…”

“…Indeed, after peripheral nerve lesions, there is a consistent reduction in opioid-receptor expression in primary nociceptive neurons (28). Recently, it was shown that during neuropathic states, there is a reduction of K ATP currents in rat primary sensitive neurons, probably by a defect in upmodulation of these currents by NO and the Ca 2+ /Calmodulin/ CAMKII pathway (24,29). These findings could be associated with the enhancement of pain sensitivity in neuropathy.…”

The Involvement of NO–cGMP–ATP Sensitive K+ Channels Pathway in Protocatechuic Acid Peripheral Analgesia

“…The NO/cGMP/ATP-sensitive K + channel pathway is one of the mechanism of action of some analgesics such as diclofenac and fentanyl. [4][5][6] However, according to our test results, the peripheral antinociceptive action of PCA involved another NO related pain pathway, not NO-cGMP-ATP sensitive K + channels pathway. The other possible NO related pain pathway involvement in PCA antinociception is still under investigation.…”

“…In vivo pharmacological studies imply that ATP-sensitive K + channels in peripheral sensory neurons may be activated indirectly via the NO/cGMP/ PKG pathway and this pathway is one of the mechanism of action for various analgesic drugs such as diclofenac and fentanyl. [4][5][6] The acetic acid induced writing test is one of the most commonly used methods for measuring peripheral analgesic activity in mice. 7 Previously, in another study, 8 we found that 150 and 300 mg/kg (p.o.)…”

Knockdown of the neuronal nitric oxide synthase gene retard the development of the cerebellar granule neurons in vitro

“…To date, two major signaling mechanisms were considered to mediate the cellular effects of NO, namely the cGMP pathway and S-nitrosylation. The latter has been found to mediate NO-induced anti-apoptosis function and neuronal protection recently (Tenneti et al, 1997;Lipton, 1999;Kawano et al, 2009).…”