Abstract
Traumatic brain injury (TBI) is a leading cause of death and disability in the United States and survivors often experience mental and physical health consequences that reduce quality of life. We previously reported that blockade of the nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor reduced tissue damage markers produced by blast TBI. The goal of this study was to determine the extent to which N/OFQ and NOP receptor levels change following mild (mTBI) and moderate TBI (modTBI) and whether the absence of the NOP receptor attenuates TBI-induced sequelae. Male and female NOP receptor knockout (KO) or wild-type (WT) rats received craniotomy-only (sham), or craniotomy plus mild (mTBI), or moderate TBI (modTBI) impact to the left cerebral hemisphere. Neurological and vestibulomotor deficits, and nociceptive hyperalgesia and allodynia found in WT male and female rats following mTBI and modTBI were greatly reduced or absent in NOP receptor KO rats. NOP receptor levels increased in brain tissue from injured males but remained unchanged in females. NF-L and GFAP expression were reduced in NOP receptor KO rats compared to WT following TBI. Levels of N/OFQ in injured brain tissue correlated with neurobehavioral outcomes and GFAP in WT males, but not with KO male or WT and KO female rats. This study reveals a significant contribution of the N/OFQ-NOP receptor system to TBI-induced deficits and suggests that the NOP receptor should be regarded as a potential therapeutic target for TBI.
Significance Statement This study revealed that NOP receptor KO animals experienced fewer TBI-induced deficits than their WT counterparts in a sex- and injury severity-dependent manner, suggesting that NOP receptor antagonists may be a potential therapy for TBI.
- anxiety
- behavioral neuroscience
- brain/CNS
- drug development/discovery
- g protein-coupled receptors (GPCRS)
- genotype
- movement disorders
- Neuroprotection
- nociceptin/orphanin FQ
- pain
- © 2023 The Authors. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial License, which permits use, distribution, and reproduction in any medium, provided that the original work is properly cited and is not used for commercial purposes.