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Nitric oxide modulates μ‐opioid receptor function in vitro
Author(s) -
Huang Lillian,
Wyse Bruce D.,
Williams Craig M.,
Smith Maree T.
Publication year - 2019
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/1440-1681.13091
Subject(s) - nitric oxide , in vitro , opioid , pharmacology , chemistry , function (biology) , opioid receptor , receptor , neuroscience , biophysics , medicine , microbiology and biotechnology , biochemistry , biology , organic chemistry
Painful diabetic neuropathy ( PDN ) is a type of peripheral neuropathic pain that develops as a consequence of prolonged hyperglycaemia‐induced injury to the long nerves. Apart from pain, PDN is also characterized by morphine hyposensitivity. Intriguingly, in streptozotocin ( STZ )‐induced diabetic rats exhibiting marked morphine hyposensitivity, dietary administration of the nitric oxide ( NO ) precursor, L‐arginine at 1 g/d, progressively rescued morphine efficacy and potency over an 8‐week treatment period. In earlier work, single bolus doses of the furoxan nitric oxide ( NO ) donor, PRG 150 (3‐methylfuroxan‐4‐carbaldehyde), evoked dose‐dependent pain relief in STZ ‐diabetic rats but the efficacious doses were 3‐4 orders of magnitude higher in advanced diabetes than that required in early STZ diabetes. Together, these findings suggested a role for NO in the modulation of μ‐opioid ( MOP ) receptor signalling. Therefore, the present study was designed to assess a role for NO released from PRG 150, in modulating MOP receptor function in vitro. Here, we show an absolute requirement for the MOP receptor, but not the δ‐opioid ( DOP ) or the κ‐opioid ( KOP ) receptor, to transduce the cellular effects of PRG 150 on forskolin‐stimulated cAMP responses in vitro. PRG 150 did not interact with the classical naloxone‐sensitive binding site of the MOP receptor, and its effects on cAMP responses in HEK ‐ MOP cells were also naloxone‐insensitive. Nevertheless, the inhibitory effects of PRG 150 on forskolin‐stimulated cAMP responses in HEK ‐ MOP cells were dependent upon pertussis toxin ( PTX )‐sensitive G i/o proteins as well as membrane lipid rafts and src kinase. Together, our findings implicate a role for NO in modulating MOP receptor function in vivo.