Anxiolytic-like effect of central administration of NOP receptor antagonist UFP-101 in rats submitted to the elevated T-maze.

Depression and anxiety disorders present several genetic and neurobiological similarities. Drugs with antidepressant activity are effective in the treatment of a wide spectrum of anxiety disorders. Preclinical results showed that acute and chronic treatment with the NOP antagonist [Nphe(1),Arg(14),Lys(15)]N/OFQ-NH(2) (UFP-101) produced antidepressant-like effects in rodents. Thus, the present study aimed to investigate the effect of central administration of UFP-101 on the anxiety-related behavior in rats as evaluated in the elevated T-maze (ETM) test. Our results showed that UFP-101 reduced the latency of inhibitory avoidance in the ETM, indicating an anxiolytic-like effect. The endogenous peptide N/OFQ prevented this anxiolytic-like action of UFP-101, demonstrating its modulation via central NOP receptors. However, UFP-101 failed to interfere with the latency to escape. No change was observed in locomotor activity after UFP-101 treatment, ruling out any nonspecific motor effect. In conclusion, our results showed that the central administration of UFP-101 presents an anxiolytic-like effect in rats evaluated in the ETM test, providing new insights for drug development to treat anxiety disorders targeting the N/OFQ-NOP receptor system.