Effects of stellate ganglion block on inflammation and autophagy of spinal cord neurons in rats with neuropathic pain after spinal cord injury

Abstract

Objective: To assess the therapeutic effects of stellate ganglion block (SGB) on spinal cord injury (SCI)-induced neuropathic pain in rats, and to explore its potential mechanisms in alleviating neuropathic pain, thereby providing a theoretical foundation for clinical treatment.

Methods: A rat model of SCI was established, and animals were randomly assigned to one of three groups: the sham surgery group (Sham), the SCI group (SCI), or the SCI group treated with SGB (SCI + SGB). Motor function was assessed using the Basso Beattie Bresnahan (BBB) locomotor rating scale, while thermal hyperalgesia was evaluated using hot plate test. Enzyme-linked immunosorbent assay (ELISA) was utilized to measure the levels of inflammatory cytokines, including interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α), within the spinal cord. Hematoxylin-eosin (HE) staining was performed to observe spinal cord histopathology. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining was used to detect apoptotic cells, and transmission electron microscopy was employed to visualize autophagosomes. Expression of autophagy-related proteins LC3-II/LC3-I and p62 was examined via Western blotting.

Results: Compared with the sham group, rats in the SCI group displayed impaired hind limb motor function, decreased pain thresholds, elevated inflammatory cytokine levels, significant spinal cord pathology, increased apoptosis, altered expression of autophagy-related protein, and disrupted autophagic flux. In contrast, SGB treatment improved motor function, alleviated pain, reduced inflammatory cytokines levels, mitigated spinal cord injury and apoptosis, and enhanced autophagy with improved autophagic flux.

Conclusions: Stellate ganglion block alleviates neuropathic pain in SCI-induced rats by reducing pro-inflammatory cytokine levels, mitigating spinal cord apoptosis and injury, promoting autophagy, and restoring autophagic flux in the spinal cord.

Keywords: Stellate ganglion block; neuropathic pain; spinal cord injury.

Figure 1

BBB scoring system evaluation of hind limb motor function in rats with spinal cord injury. Mean ± Standard Error of the Mean (SEM) describes the data. n = 42. Compared with the sham surgery group, meeting the criteria of P < 0.05, represented by *. Compared with the spinal cord injury (SCI) group, meeting the criteria of P < 0.05, represented by #.

Figure 2

Schematic diagram of using paw thermal withdrawal latencies (PWL) to quantify pain related content in rats. Mean ± Standard Error of the Mean (SEM) describes the data. n = 42. Compared with the sham surgery group, meeting the criteria of P < 0.01, represented by **, meeting the criteria of P < 0.0001, represented by ****. Compared with the spinal cord injury (SCI) surgery group, meeting the criteria of P < 0.01, represented by ##.

Figure 3

Stellate ganglion block (SGB) reduces the levels of IL-1β and other factors in the spinal cord of rats after spinal cord injury. A: Used enzyme-linked immunosorbent assay (ELISA) to evaluate the levels of interleukin-1β (IL-1β) in spinal cord samples from different groups. B: Used ELISA to evaluate the levels of interleukin-6 (IL-6) in spinal cord samples from different groups. C: Evaluate the levels of tumor necrosis factor-α (TNF-α) in spinal cord samples from different groups using ELISA. Mean ± Standard Error of the Mean (SEM) describes the data. n = 42. Compared with the sham group, meeting the criteria of P < 0.05, represented by *. Compared with the spinal cord injury (SCI) group, meeting the criteria of P < 0.05, represented by #.

Figure 4

Histopathological observation of spinal cord tissue in each group.

Figure 5

Stellate ganglion block (SGB) can inhibit apoptosis of spinal cord cells induced by SCI. A: Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining was employed to assess the levels of apoptosis in hippocampal tissues across different groups of rats, ×100. B: Quantitative analysis of TUNEL-positive cells was conducted. Data: Mean ± Standard Error of the Mean (SEM). n = 42. ***P < 0.001 vs Sham group. ##P < 0.01 vs spinal cord injury (SCI) group.

Figure 6

Changes of microautophagosomes in the rat spinal cord seven days after injury using transmission electron microscopy. A: Sham group. B: SCI group. C: SCI + SGB group.

Figure 7

Stellate ganglion block (SGB) enhances autophagy in the spinal cords of rats with SCI. A: Western Blot analysis was used to determine the levels of Microtubule-associated protein 1 light chain 3 (LC3)-II/LC3-I proteins in spinal cord tissues across different groups of rats. B: Western Blot analysis was used to determine the levels of P62 protein in spinal cord tissues across different groups of rats. Data: Mean ± Standard Error of the Mean (SEM). n = 42. *P < 0.05, ***P < 0.001 vs Sham group. ##P < 0.01, ###P < 0.001 vs spinal cord injury (SCI) group.