Nociceptin/orphanin FQ induces simultaneously anxiolytic and amnesic effects in the mouse elevated T-maze task

Studies have shown a close relationship between anxiety and aversive memory processing, but few animal models are suitable for investigating the effects of a given compound on anxiety and memory simultaneously. A growing body of evidence suggests anxiolytic and amnesic effects of nociceptin/orphanin FQ (N/OFQ). The mouse elevated T-maze (ETM) has been shown to detect the effects of drugs on anxiety and memory at the same time. In this study, the effects of intracerebroventricular N/OFQ injected before or immediately after training session were assessed in the ETM task. When pretraining injected, N/OFQ 0.1 nmol significantly decreased the latency to enter an open arm in the training session compared to control, which is suggestive of anxiolysis. In addition, N/OFQ (0.1 and 1 nmol) significantly reduced the latency to enter an open arm during the test session compared to control, thus suggesting memory impairments. However, when N/OFQ was administered posttraining, it did not affect memory retrieval. No alterations in locomotion were detected in N/OFQ-treated mice in the open field test. In conclusion, these findings are discussed considering the simultaneous anxiolytic and amnesic effects of N/OFQ.