The ability of orexin-A to modify pain-induced cyclooxygenase-2 and brain-derived neurotrophic factor expression is associated with its ability to inhibit capsaicin-induced pulpal nociception in rats

Abstract

Background: The rostral ventromedial medulla (RVM) is a critical region for the management of nociception. The RVM is also involved in learning and memory processes due to its relationship with the hippocampus. The purpose of the present study was to investigate the molecular mechanisms behind orexin-A signaling in the RVM and hippocampus's effects on capsaicin-induced pulpal nociception and cognitive impairments in rats. Methods: Capsaicin (100 g) was applied intradentally to male Wistar rats to induce inflammatory pulpal nociception. Orexin-A and an orexin-1 receptor antagonist (SB-334867) were then microinjected into the RVM. Immunoblotting and immunofluorescence staining were used to check the levels of cyclooxygenase-2 (COX-2) and brain-derived neurotrophic factor (BDNF) in the RVM and hippocampus. Results: Interdental capsaicin treatment resulted in nociceptive responses as well as a reduction in spatial learning and memory. Additionally, it resulted in decreased BDNF and increased COX-2 expression levels. Orexin-A administration (50 pmol/1 μL/rat) could reverse such molecular changes. SB-334867 microinjection (80 nM/1 μL/rat) suppressed orexin's effects. Conclusions: Orexin-A signaling in the RVM and hippocampus modulates capsaicininduced pulpal nociception in male rats by increasing BDNF expression and decreasing COX-2 expression.

Mechanism of spinal cord injury regeneration and the effect of human neural stem cells-secretome treatment in rat model

“…In addition, BDNF also works through the tropomyosin kinase B receptor and low-affinity nerve growth factor receptor (GFR) commonly called p75[ 45 ]. Shahsavari et al [ 46 ] state that BDNF has neurophysiological functions such as nociception, cognition, and memory.…”

The mechanism of human neural stem cell secretomes improves neuropathic pain and locomotor function in spinal cord injury rat models: through antioxidant, anti-inflammatory, anti-matrix degradation, and neurotrophic activities

“…This research showed that HNSC-secretome increases BDNF. Shahsavari et al [ 44 ] stated that BDNF is a molecule that is involved in various neurophysiological functions such as nociception, learning, and memory. BDNF is a neurotrophin that is important in the regulation of several neurogeneses, such as collateral growth promotion, neuronal branching, dendrite formation, and synaptic plasticity [ 45 ].…”