Analgesic effects of neurotensin agonists in a rat bone cancer pain model

Abstract

Bone metastases are a source of intractable pain, resistant to conventional opioid and non-opioid analgesics. The neurotensin system represents a potential pathway toward bone cancer pain (BCP) relieve via the inhibition of its receptors NTS1 and NTS2. Capitalizing on our recent results using neurotensin analogs in inflammatory and neuropathic pain models, we here show, for the first time, a potential role for neurotensin receptors agonists in the treatment of BCP. The novel non-selective agonist JMV-2009 (300 g/kg) reversed mechanical allodynia in our rodent BCP model at both early and late stages of the disease. The NTS2-selective agonist JMV-431 (90 g/kg), in addition to anti-allodynia, also had an effect on weight bearing deficits. In parallel, we tested proven analgesics from several classes to put the effect of neurotensin analogs in perspective and found that morphine (3 mg/kg), tramadol (15 mg/kg) and amitriptyline (10 mg/kg) had mild effects on BCP while the cannabinoid nabilone (1 mg/kg) significantly reversed both allodynia and weight bearing deficits. Taken together, our results affirm the potential of the modulation of the neurotensin system for the development of new analgesics for the treatment of bone cancer pain.