Orexin-1 Receptor Antagonist SB-334867 Enhances Formalin-Induced Nociceptive  Behaviors in Adult Male Rats

Masoumeh  Kourosh-Arami; Alireza  Komaki; Masoumeh  Gholami

doi:10.18502/ajmb.v16i1.14168

Masoumeh Kourosh-Arami Department of Neuroscience, School of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran
Alireza Komaki Department of Neuroscience, School of Science and Advanced Technologies in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
Masoumeh Gholami Department of Physiology, Medical College, Arak University of Medical Sciences, Arak, Iran

DOI: https://doi.org/10.18502/ajmb.v16i1.14168

Keywords: Formalin, Nociception, Orexin receptor 1, Orexin, SB-334867

Abstract

Background: Orexin (hypocretin) is one of the hypothalamic neuropeptides that plays a critical role in some behaviors including feeding, sleep, arousal, reward processing, and drug addiction. Neurons that produce orexin are scattered mediolaterally within the Dorsomedial Hypothalamus (DMH) and the lateral hypothalamus. In the current research, we assessed the impact of prolonged application of the antagonist of Orexin Receptor 1 (OXR1) on nociceptive behaviors in adult male rats.

Methods: Sixteen Wistar rats received subcutaneous (s.c.) injections of the OXR1 antagonist, SB-334867 (20 mg/kg, i.p.), or its vehicle repetitively from Postnatal Day 1 (PND1)-PND30. On the 30th day following the final application of the OXR1 antagonist formalin-provoked pain was evaluated by injecting formalin.

Results: Administration of the OXR1 antagonist in the long-term augmented the formalin-provoked nociceptive behaviors in interphase and phase II of the formalin-induced pain.

Conclusion: Current results showed that the continued inhibiting OXR1 might be implicated in formalin-induced nociceptive behaviors. Therefore, the present study highlighted the effect of orexin on analgesia.