Novel hybrid peptide BNT12 displays potent antinociception with limited opioid-like side effects at the spinal level

The development of multi-target opioids has emerged as a promising strategy to mitigate opioid-related side effects. We have previously designed a novel hybrid peptide BNT12 by combining opioid and neurotensin pharmacophores, which exhibited supraspinal antinociception. Herein, the antinociceptive properties of a novel hybrid peptide, BNT12, were evaluated across various preclinical pain models following intrathecal (i.t.) administration. Our results showed that spinal administration of BNT12 produced potent antinociception in acute pain. The antinociceptive effects of BNT12 were likely mediated through μ- and δ-opioid receptors, as well as the neurotensin receptor 1 (NTSR1) and 2 (NTSR2). BNT12 also exhibited significant antinociceptive activities in spared nerve injury (SNI)-induced neuropathic pain, complete Freund's adjuvant (CFA)-induced inflammatory pain, acetic acid-induced visceral and formalin-induced pain at the spinal level. Additionally, BNT12 significantly inhibited the microglial activation and decreased the mRNA expression levels of TNF-α and IL-1β in the spinal dorsal horn of SNI model. It is noteworthy that BNT12 exhibited substantially reduced acute and chronic antinociceptive tolerance. Furthermore, i.t. administered BNT12 showed minimal or no side effects on conditioned place preference response, naloxone-precipitated withdrawal response, acute hyperlocomotion, gastrointestinal transit, and motor coordination. The present investigation demonstrated that the hybrid peptide BNT12 exhibited potent and durable antinociception with minimal opioid-like side effects at the spinal level. Therefore, BNT12 might serve as a promising candidate to alleviate pain with a favourable side effect profile.