Midazolam and ropivacaine act synergistically to inhibit bone cancer pain with different mechanisms in rats

Potential Role of Remimazolam in Alleviating Bone Cancer Pain in Mice via Modulation of Translocator Protein in Spinal Astrocytes

Bone cancer pain (BCP) is a complex clinical challenge, with current treatments often falling short of providing adequate relief. Remimazolam, a benzodiazepine receptor agonist recognized for its anxiolytic effects, has emerged as a potential agent in managing BCP. This study explores the analgesic properties of remimazolam and its interaction with the translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor, in spinal astrocytes. In the context of BCP, previous research has indicated that TSPO expression in spinal astrocytes may serve a protective regulatory function in neuropathic pain models. Building on this, the BCP mice received various doses of remimazolam on the 15th day post-inoculation, and pain behavior was assessed over time. The results showed that BCP induced an upregulation of TSPO and astrocyte activation in the spinal dorsal horn, alongside increased extracellular signal-regulated kinase (ERK) signaling and inflammatory cytokine expression. Remimazolam administration resulted in a dose-dependent reduction of pain behaviors, which corresponded with a decrease in both ERK pathway activation and inflammatory factor expression. This suggests that remimazolam's analgesic effects are mediated through its action as a TSPO agonist, leading to the attenuation of neuroinflammation and pain signaling pathways. Importantly, the analgesic effects of remimazolam were reversed by the TSPO antagonist PK11195, underscoring the pivotal role of TSPO in the drug's mechanism of action. This reversal also reinstated the heightened levels of ERK activity and inflammatory mediators, further confirming the involvement of TSPO in the modulation of these pain-related processes. These findings open new avenues for the therapeutic management of bone cancer pain, positioning remimazolam as a promising candidate for further investigation and development.

Translocator Protein 18 kDa (TSPO) as a Novel Therapeutic Target for Chronic Pain

Chronic pain is an enormous modern public health problem, with significant numbers of people debilitated by chronic pain from a variety of etiologies. Translocator protein 18 kDa (TSPO) was discovered in 1977 as a peripheral benzodiazepine receptor. It is a five transmembrane domain protein, mainly localized in the outer mitochondrial membrane. Recent and increasing studies have found changes in TSPO and its ligands in various chronic pain models. Reversing their expressions has been shown to alleviate chronic pain in these models, illustrating the effects of TSPO and its ligands. Herein, we review recent evidence and the mechanisms of TSPO in the development of chronic pain associated with peripheral nerve injury, spinal cord injury, cancer, and inflammatory responses. The cumulative evidence indicates that TSPO-based therapy may become an alternative strategy for treating chronic pain.

Ropivacaine Inhibits the Growth, Migration and Invasion of Gastric Cancer Through Attenuation of WEE1 and PI3K/AKT Signaling via miR-520a-3p

BACKGROUND

Metastasis remains one of the greatest challenges involved in treating gastric cancer (GC). Ropivacaine (Rop) is not only a well-documented local anesthetic medicament but also has been reported to exert an antitumor role in cancer development. This study explored the effects of ropivacaine on the growth, migration and invasion of gastric cancer and the underlying mechanisms.

METHODS

Cell Counting Kit-8 (CCK8) assay was conducted to test the effect of Rop on the proliferation of AGS and BGC-823 GC cells. Moreover, cell apoptosis, migration and invasion were examined by flow cytometry and transwell assay, respectively. The expression of miR-520a-3p was determined by qRT-PCR. miRNA targeting sites were analyzed using bioinformatics analysis and dual-luciferase reporter assay. Protein levels of WEE1 and PI3K/AKT were detected by Western blot. Furthermore, the tumor-forming experiment of nude mice was used to detect the growth of cells in vivo.

RESULTS

Rop inhibited proliferation but promoted apoptosis of GC cells. Besides, the migration and invasion of GC cells were also inhibited by Rop. Moreover, miR-520a-3p expression was enhanced by Rop, and transfection with miR-520a-3p mimic decreased cell proliferation, migration and invasion. The upregulation of miR-520a-3p was partly contributed to the inhibitory effect of ropivacaine on GC cell lines. Finally, Rop inactivated WEE1 and PI3K/AKT pathway via upregulation of miR-520a-3p.

CONCLUSION

Our results suggested that Rop decreased growth, migration and invasion of GC cells via regulating miR-520a-3p expression and further inactivated WEE1 and PI3K/AKT signaling pathways.

B14 ameliorates bone cancer pain through downregulating spinal interleukin-1β via suppressing neuron JAK2/STAT3 pathway

Curcumin has several pharmacological properties such as anti-inflammatory, antioxidant, and neuroprotective activities. B14 is a curcumin analogue and is considered to be a more potent compound with preserved pharmacodynamic activities. Based on the previous research studies, janus-activated kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) signaling pathway plays a remarkable role in inflammation, chronic pain, and even contributes to the pathogenesis of neuropathic pain. Pro-inflammatory cytokines interleukin-1β is a downstream factor of JAK2/STAT3 signal transition pathway, which participates in neuron injury and inflammation. We hypothesized that this signal transition pathway played an indispensable role in bone cancer pain. We herein established a bone cancer pain model to monitor the variation of JAK2/STAT3 signal transduction pathway and measured the effect of B14. The results in bone cancer pain model showed that (i) the levels of interleukin-1β were elevated, and the ratios of p-JAK2/JAK2 and p-STAT3/STAT3 were increased; (ii) double immunostaining showed that p-JAK2, p-STAT3, and interleukin-1β were colocalized primarily with neurons, rather than with astrocytes or microglial cells; (iii) B14 injection (intraperitoneally) markedly eased bone cancer pain; (iv) Western blotting showed that B14 injection lowered p-JAK2, p-STAT3, and interleukin-1β levels, meanwhile the ratios of p-JAK2/JAK2 and p-STAT3/STAT3 was reduced; (v) immunofluorescence results also confirmed decreased levels of p-JAK2, p-STAT3, and interleukin-1β in B14 treatment group. These findings suggested that B14 injection attenuated bone cancer pain in rats. This intervention inhibited JAK2/STAT3 cascade activation, downregulating interleukin-1β expression in spinal dorsal horn.

Nanocarrier-mediated Delivery of CORM-2 Enhances Anti-allodynic and Anti-hyperalgesic Effects of CORM-2

Neuropathic pain is a devastating chronic condition and effective treatments are still lacking. Carbon monoxide-releasing molecule-2 (CORM-2) as a carbon monoxide (CO) carrier, exerts potent anti-neuropathic pain effects; however, its poor water solubility and short half-life hinder its clinical utility. Therefore, the aim of this study was to investigate whether CORM-2-loaded solid lipid nanoparticles (CORM-2-SLNs) enhance the anti-allodynic and anti-hyperalgesic effects of CORM-2 in a rat chronic constriction injury (CCI) model. CORM-2-SLNs were prepared using a nanotemplate engineering technique with slight modifications. The physiochemical properties of CORM-2-SLNs were characterized and CO release from CORM-2-SLNs was assessed using a myoglobin assay. CO was slowly released from CORM-2-SLNs, was observed, and the half-life of CO release was 50 times longer than that of CORM-2. In vivo results demonstrate that intraperitoneal administration of CORM-2-SLNs (5 and 10 mg/kg/day, ip) once daily for seven consecutive days significantly reduced the mechanical allodynia and mechanical hyperalgesia compared with CORM-2 (10 mg/kg/day, ip). RT-PCR and Western blot analyses on days 7 and 14, revealed that treatment with CORM-2-SLNs resulted in greater reductions in the CCI-elevated levels of heme-oxygenase-2 (HO-2); inducible nitric oxide synthase (iNOS); neuronal NOS (nNOS); and inflammatory mediators (TNF-α, IBA-1, and GFAP) in the spinal cord and dorsal root ganglions compared with treatment with CORM-2. In contrast, HO-1 and IL-10 were significantly increased in the CORM-2-SLN-treated group compared with the group treated with CORM-2. These data indicate that CORM-2-SLNs are superior to CORM-2-S in alleviating mechanical allodynia and mechanical hyperalgesia.

Midazolam prevents motor neuronal death from oxidative stress attack mediated by JNK-ERK pathway

Midazolam is a sedative used by patients with mechanical ventilation. However, the potential clinical value is not fully explored. In this report, we made use of a neuroblastoma-spinal cord hybrid motor neuron-like cell line NSC34, and elucidated the potential role of Midazolam on these cells under the insult of oxidative stress. We found the protective effect of Midazolam on motor neurons against cytotoxicity induced by the combination of oligomycin A and rotenone (O/R) or phenylarsine oxide. The characteristics of apoptosis, such as the ratio of TUNEL+ cells or the expression level of cleaved Caspase-3, was decreased by 22 or 45% in the presence of Midazolam. Furthermore, this effect was correlated with the JNK-ERK signaling pathway. Either phosphorylation of ERK or JNK was positively or negatively modulated with the treatment of Midazolam in NSC34 cells attacked by reactive oxygen species. Meanwhile, inhibition or activation of the JNK-ERK pathway regulated the protective effect of Midazolam on NSC34 cells with oxidative stress insult. Collectively, this study elucidated a previously unidentified clinical effect of Midazolam, and put forward the great promise that Midazolam may be considered as a potential candidate to the treatment of motor neuron disease.