Opioid receptor stimulation does not affect cellular hypoxia-induced gene responses mediated by hypoxia-inducible factor 1 in cultured cell lines.

Hypoxia induces a series of adaptive physiological responses including gene inductions. Hypoxia-inducible factor 1 (HIF-1) is a master transcription factor that regulates hypoxia-induced gene expression to maintain homeostasis in the living body. Opioids are potent analgesic agents that are widely used in clinical practice. Therefore, we investigated the effect of opioids on HIF-1 activity. SH-SY5Y human neuronal cells, which express opioid receptors intrinsically, were cultured under 1% or 20% O2 conditions with or without treatment by DAGO, DPDPE, or U-50488, which are the selective agonists of mu-, delta-, and kappa-opioid receptors, respectively. Expression of subunits of HIF-1, HIF-1alpha, and HIF-1beta were examined by Western blot using specific antibodies. Expression of the HIF-1-dependent gene were investigated by reporter assay. None of the selective agonists of opioid receptors tested affected HIF-1 activation by hypoxia. Therefore, it is suggested that opioid receptor-mediated signals do not affect HIF-1-dependent cellular hypoxia-induced gene responses.