The behavioral responses exerted by spinal administration of the opioid-neurotensin hybrid peptide, PK23, were studied in adult male rats. The antinociceptive effect upon exposure to a thermal stimulus, as well as tolerance development, was assessed in an acute pain model. The PK23 chimera at a dose of 10 nmol/rat produced a potent pain-relieving effect, especially after its intrathecal administration. Compared with intrathecal morphine, this novel compound was found to possess a favourable side effect profile characterized by a reduced scratch reflex, delayed development of analgesic tolerance or an absence of motor impairments when given in the same manner, though some animals died following barrel rotation as a result of its i.c.v. administration (in particular at doses higher than 10 nmol/rat). Nonetheless, these results suggest the potential use of hybrid compounds encompassing both opioid and neurotensin structural fragments in pain management. This highlights the enormous potential of synthetic neurotensin analogues as promising future analgesics.

在成年雄性大鼠中研究了脊髓施用阿片类药物-神经降压素杂合肽PK23所产生的行为反应。在急性疼痛模型中评估了暴露于热刺激后的抗伤害感受作用以及耐受性的发展。剂量为10 nmol /大鼠的PK23嵌合体可产生有效的止痛作用，尤其是在鞘内给药后。与鞘内吗啡相比，发现这种新型化合物具有良好的副作用，其特征在于以相同的方式给药时，划痕反射减少，镇痛耐受性延迟发展或无运动障碍，尽管有些动物在旋转时因旋转而死亡。 icv给药的结果（尤其是剂量高于10 nmol /大鼠）。尽管如此，这些结果表明，包含阿片样物质和神经降压素结构片段的杂合化合物在疼痛治疗中的潜在用途。这突出了合成神经降压素类似物作为有希望的未来镇痛药的巨大潜力。