The effect of urinary trypsin inhibitor against neuropathic pain in rat models

Ulinastatin inhibits microglia activation in spinal cord via P2Y12 receptor in a rat neuropathic pain model

Ulinastatin, a broad spectrum of serine protease inhibitor, has been found to alleviate neuropathic pain (NPP). However, its mechanism is not completely clear. Here, a sciatic nerve ligation rat model and BV2 microglial cells were used to investigate the effect of Ulinastatin on the activation of microglia and P2Y12 receptors in vivo and in vitro. Levels of P2Y12 receptor and NF-κB (P65) expression in the dorsal horn of the lumbar enlargement region of the spinal cord and BV2 cells were assessed by immunohistochemistry and double-label immunofluorescence assays. Levels of IL-1β and TNF-α in cell culture medium and cerebrospinal fluid (CSF) were examined by ELISA. The results showed that Ulinastatin reduced the release of inflammatory IL-1β and TNF-α by inhibiting the activation of spinal microglia. Ulinastatin down-regulated P2Y12 receptor and NF-κB (P65) expression in the spinal microglia of the chronic constrictive injury model. The results indicated that Ulinastatin may attenuate the activation of spinal microglia after peripheral nerve injury by inhibiting the activation of P2Y12 receptor signal pathway in microglia. NF-kB may play a key role in the mechanism of Ulinastatin.

The analgesic effects of ulinastatin either as a single agent or in combination with sufentanil: A novel therapeutic potential for postoperative pain

Ulinastatin is a broad-spectrum protease inhibitor widely used for the treatment of various inflammation-related diseases owing to its recognized excellent anti-inflammatory and cytoprotective properties. However, whether ulinastatin can relieve postoperative pain remains unclear. In this study, we evaluated the analgesic effects of ulinastatin administered either as a single agent or in combination with sufentanil in a validated preclinical rat model of postoperative pain induced by plantar incision. We found that incisional surgery on the hind paw of these rats induced sustained ipsilateral mechanical pain hypersensitivity that lasted for at least 10 days. A single intraperitoneal (i.p.) injection of ulinastatin prevented the development and reversed the maintenance of incision-induced mechanical pain hypersensitivity in a dose-dependent manner. However, ulinastatin had no effect on the baseline nociceptive threshold. Moreover, repeated i.p. injections of ulinastatin persistently attenuated incision-induced mechanical pain hypersensitivity and promoted recovery from the surgery. The rats did not develop any analgesic tolerance over the course of repeated injections of ulinastatin. A single i.p. injection of ulinastatin was also sufficient to inhibit the initiation and maintenance of incision-induced hyperalgesic priming when the rats were subsequently challenged with an ipsilateral intraplantar prostaglandin E2 injection. Furthermore, the combined administration of ulinastatin and sufentanil significantly enhanced the analgesic effect of sufentanil on postoperative pain, which involved mechanisms other than a direct influence on opioid receptors. These findings demonstrated that ulinastatin had a significant analgesic effect on postoperative pain and might be a novel pharmacotherapeutic agent for managing postoperative pain either alone or as an adjuvant.

Ulinastatin inhibits NLRP3-induced apoptosis in a PD cell model

Background

Emerging evidence suggests that inflammation induced by the inflammasome plays a crucial role in the course of Parkinson’s disease (PD). Ulinastatin (UTI) has shown significant anti-inflammatory effects. However, few studies have examined whether UTI protects neurons through its anti-inflammatory effects in PD. The purpose of this study is to determine whether UTI exerts neuroprotection in a PD cell model and to explore the mechanisms.

Methods

SH-SY5Y cells and nerve growth factor (NGF)-treated PC12 cells were used to establish MPP⁺ induced PD cell models. Cells were pre-treated with UTI, then cell viabilities were detected using the MTT assay. Lactate dehydrogenase (LDH) release was detected using the LDH release assay kit. Inflammatory factors such as IL-1β, IL-6, and TNF-α were detected using ELISA. The expression levels of TH, NLRP3, caspase-1, ASC, IL-1β, and IL-18 were measured using western blotting, and DA release was detected using HPLC. A NLRP3 activator Nigericin was used to verify the effect of NLRP3 in the neuroprotective mechanism of UTI.

Results

We observed decreased cell viability, increased apoptosis, and increased inflammatory factors such as IL-1β, IL-6, and TNF-α in the MPP⁺ induced PD model. We also found decreased DA secretion and TH expression, as well as increased NLRP3, caspase-1, ASC, IL-1α, and IL-18 expression in the MPP⁺ induced PD model. These changes were significantly attenuated by UTI pre-treatment in a dose dependent manner. NLRP3 activator Nigericin markedly increased LDH release, accelerated apoptosis, increased inflammation levels and decreased DA secretion and TH expression, suggesting that Nigericin eliminated the neuroprotective effect of UTI on MPP⁺ treated cells.

Conclusions

Our data demonstrated that UTI pre-treatment performed a neuroprotective role in the MPP⁺ induced PD cell models by inhibiting the NLRP3 pathway.

Ulinastatin alleviates traumatic brain injury by reducing endothelin-1

Background

Brain edema is one of the major causes of fatality and disability associated with injury and neurosurgical procedures. The goal of this study was to evaluate the effect of ulinastatin (UTI), a protease inhibitor, on astrocytes in a rat model of traumatic brain injury (TBI).

Methodology

A rat model of TBI was established. Animals were randomly divided into 2 groups – one group was treated with normal saline and the second group was treated with UTI (50,000 U/kg). The brain water content and permeability of the blood–brain barrier were assessed in the two groups along with a sham group (no TBI). Expression of the glial fibrillary acidic protein, endthelin-1 (ET-1), vascular endothelial growth factor (VEGF), and matrix metalloproteinase 9 (MMP-9) were measured by immunohistochemistry and western blot. Effect of UTI on ERK and PI3K/AKT signaling pathways was measured by western blot.

Results

UTI significantly decreased the brain water content and extravasation of the Evans blue dye. This attenuation was associated with decreased activation of the astrocytes and ET-1. UTI treatment decreased ERK and Akt activation and inhibited the expression of pro-inflammatory VEGF and MMP-9.

Conclusion

UTI can alleviate brain edema resulting from TBI by inhibiting astrocyte activation and ET-1 production.

Gabexate mesilate ameliorates the neuropathic pain in a rat model by inhibition of proinflammatory cytokines and nitric oxide pathway via suppression of nuclear factor-κB

Background

This study examined the effects of gabexate mesilate on spinal nerve ligation (SNL)-induced neuropathic pain. To confirm the involvement of gabexate mesilate on neuroinflammation, we focused on the activation of nuclear factor-κB (NF-κB) and consequent the expression of proinflammatory cytokines and inducible nitric oxide synthase (iNOS).

Methods

Male Sprague-Dawley rats were used for the study. After randomization into three groups: the sham-operation group, vehicle-treated group (administered normal saline as a control), and the gabexate group (administered gabexate mesilate 20 mg/kg), SNL was performed. At the 3rd day, mechanical allodynia was confirmed using von Frey filaments, and drugs were administered intraperitoneally daily according to the group. The paw withdrawal threshold (PWT) was examined on the 3rd, 7th, and 14th day. The expressions of p65 subunit of NF-κB, interleukin (IL)-1, IL-6, tumor necrosis factor-α, and iNOS were evaluated on the 7th and 14th day following SNL.

Results

The PWT was significantly higher in the gabexate group compared with the vehicle-treated group (P < 0.05). The expressions of p65, proinflammatory cytokines, and iNOS significantly decreased in the gabexate group compared with the vehicle-treated group (P < 0.05) on the 7th day. On the 14th day, the expressions of p65 and iNOS showed lower levels, but those of the proinflammatory cytokines showed no significant differences.

Conclusions

Gabexate mesilate increased PWT after SNL and attenuate the progress of mechanical allodynia. These results seem to be involved with the anti-inflammatory effect of gabexate mesilate via inhibition of NF-κB, proinflammatory cytokines, and nitric oxide.

Synergistic Interaction Between Dexmedetomidine and Ulinastatin Against Vincristine-Induced Neuropathic Pain in Rats

Antimicrotubulin chemotherapeutic agents such as vincristine (VCR), often induce peripheral neuropathic pain. It is usually permanent and seriously harmful to cancer patients' quality of life and can result in the hampering of clinical treatments. Currently, there is no definitive therapy, and many of the drugs approved for the treatment of other neuropathic pain have shown little or no analgesic effect. It is therefore vital to find new and novel therapeutic strategies for patients suffering from chemotherapeutic agent-induced neuropathic pain to improve patients' quality of life. This study shows that intrathecal injections of dexmedetomidine (DEX), or intraperitoneally administered ulinastatin (UTI) significantly reduces Sprague Dawley rats' mechanical allodynia induced by VCR via upregulation of interleukin-10 expression and activating the α2-adrenergic receptor in dorsal root ganglion (DRG). Moreover, when combined there is a synergistic interaction between DEX and UTI, which acts against VCR-induced neuropathic pain. This synergistic interaction between DEX and UTI may be partly attributed to a common analgesic pathway in which the upregulation of interleukin -10 plays an important role via activating α2-adrenergic receptor in rat dorsal root ganglion. The combined use of DEX and UTI does not affect the rat's blood pressure, heart rate, sedation, motor score, spatial learning, or memory function. All of these show that the combined use of DEX and UTI is an effective method in relieving VCR-induced neuropathic pain in rats.

PERSPECTIVE

This article documents the synergistic interaction between 2 widely used drugs, DEX and UTI, against VCR-induced neuropathic pain. The results provide a potential target and novel drug administrated method for the clinical treatment of chemotherapy-induced peripheral neuropathic pain.

Ulinastatin attenuates neuropathic pain via the ATP/P2Y2 receptor pathway in rat models

Ulinastatin, a serine protease inhibitor, which has anti-inflammatory properties and neuroprotective effects, is used to treat acute inflammatory disorders. Recent evidence indicates that administration of ulinastatin alleviates pain in rat model of neuropathic pain (NPP). However, its effect on NPP and the underlying mechanism requires further study. In this study, we evaluated the role of intrathecal administration of ulinastatin in rats with sciatic nerve ligation and observed the effect of ulinastatin on the ATP/P2Y2 receptor pathway. We performed mechanical and thermal sensitivity measurements, immunohistochemistry and double-label immunofluoresence studies to evaluate P2Y2 receptor and adenosine 5'-monophosphate-activated protein kinase (AMPK) expression in the dorsal horn of the lumbar enlargement region of the spinal cord, and a luciferase assay for the detection of ATP levels in the cerebrospinal fluid. The results showed that ulinastatin prevented the development of mechanical allodynia and thermal hypersensitivity in the rat sciatic nerve ligation model. Ulinastatin reduced the level of extracellular ATP, down-regulated P2Y2 receptor and AMPK expression in the spinal dorsal horn of the chronic constrictive injury model. We found that increased expression of P2Y2 receptor in microglia was likely involved in the activation of microglia after nerve injury, and ulinastatin inhibited the abnormal microglia activation in the dorsal horn after nerve injury. These findings demonstrated that ulinastatin might be a potential and effective drug for the treatment of NPP via the suppression of the ATP/P2Y2 receptor pathway.

Ulinastatin attenuates neuropathic pain induced by L5-VRT via the calcineurin/IL-10 pathway

Previous studies have shown that ulinastatin, an effective inhibitor of the inflammatory response in clinical applications, can attenuate hyperalgesia in rodents. However, the underlying mechanism remains unclear. In the present study, we first examined the change in the calcineurin level, which plays an important role in regulating cytokine release in the nervous system, following lumbar 5 ventral root transection in the rat. Furthermore, we determined whether intraperitoneal (i.p.) injection of ulinastatin attenuated pain behavior via inhibition of the calcineurin-mediated inflammatory response induced by lumbar 5 ventral root transection. The results showed that the paw withdrawal threshold and paw withdrawal latency were significantly decreased following lumbar 5 ventral root transection compared to the sham group. Neuropathic pain induced by lumbar 5 ventral root transection significantly decreased the expression of calcineurin in the DRG, and calcineurin was mostly located with NF-200-positive cells, IB4-positive cells, and CGRP-positive cells and less with GFAP-positive satellite cells. Furthermore, intrathecal (i.t.) injection of exogenous calcineurin attenuated the pain behavior induced by lumbar 5 ventral root transection. Importantly, intraperitoneal injection of ulinastatin alleviated the pain behavior and calcineurin downregulation induced by lumbar 5 ventral root transection. Lastly, the cytokine IL-10 was significantly decreased following lumbar 5 ventral root transection, and application of calcineurin (intrathecal) or ulinastatin (intraperitoneal) inhibited the IL-10 downregulation induced by lumbar 5 ventral root transection. These results suggested that ulinastatin, by acting on the CN/IL-10 pathway, might be a novel and effective drug for the treatment of neuropathic pain.

Olanzapine Attenuates Mechanical Allodynia in a Rat Model of Partial Sciatic Nerve Ligation

Background

Neuropathic pain is a global clinical problem; nevertheless, nerve injury treatment methods remain limited. Olanzapine has antinociceptive and anti-nueropathic properties; however, its preventive effects have not been assessed in nerve injury models.

Methods

We prepared a partial sciatic nerve ligation (Seltzer model) or sham-operated model in male Sprague-Dawley rats under isoflurane anesthesia. In a pre-treatment study, we administered olanzapine (10 mg/kg) intraperitoneally 1 h before nerve ligation. In post-treatment and dose-dependent studies, we injected 3 different doses of olanzapine intraperitoneally 1 h after nerve ligation. Mechanical allodynia was measured before and 7 days after surgery. Immunohistochemical analysis using anti-Iba-1 antibody was used to assess the effect of olanzapine at the spinal level.

Results

In the pre-treatment study, median withdrawal thresholds of the normal saline groups were significantly lower than those of the sham-operated groups; however, those of the olanzapine (10 mg/kg) and sham-operated groups were not different. In the post-treatment and dose-dependent studies, the median withdrawal thresholds of the olanzapine (2.5 mg/kg) and normal saline groups were not different; however, those of the olanzapine (10 and 50 mg/kg) groups were significantly higher than those of the normal saline groups. Olanzapine did not have a significant effect on the density of Iba-1 staining.

Conclusions

Olanzapine attenuated mechanical allodynia dose-dependently in the Seltzer model. This anti-allodynic effect of olanzapine was observed even when injected 1 h after nerve ligation. This effect of olanzapine appeared to be unrelated to microglia activation in the ipsilateral dorsal horn of the lumbar spinal cord.