Automated Gait Analysis in Mice with Chronic Constriction Injury

The von Frey test is a classical method that has been widely used to examine the sensory function of neuropathic pain animals. However, it has some ...

Burn Injury-Induced Pain and Depression-Like Behavior in Mice

Scalding water is the most common cause of burn injury in both elderly and young populations. It is one of the major clinical challenges because of the ...

Chungnam National University

In this study, we examined the antinociceptive effect of Cyperi rhizoma (CR) and Corydalis tuber (CT) extracts using a chronic constriction injury-induced neuropathic pain rat model. After the ligation of sciatic nerve, neuropathic pain behavior such as mechanical allodynia and thermal hyperalgesia were rapidly induced and maintained for 1 month. Repeated treatment of CR or CT (per oral, 10 or 30 mg/kg, twice a day) was performed either in induction (day 0~5) or maintenance (day 14~19) period of neuropathic pain state. Treatment of CR or CT at doses of 30 mg/kg in the induction and maintenance periods significantly decreased the nerve injury-induced mechanical allodynia. In addition, CR and CT at doses of 10 or 30 mg/kg alleviated thermal heat hyperalgesia when they were treated in the maintenance period. Finally, CR or CT (30 mg/kg) treated during the induction period remarkably reduced the nerve injury-induced phosphorylation of NMDA receptor NR1 subunit (pNR1) in the spinal dorsal horn. Results of this study suggest that extracts from CR and CT may be useful to alleviate neuropathic pain.

Antinociceptive Effect of Cyperi rhizoma and Corydalis tuber Extracts on Neuropathic Pain in Rats.

Peripheral or central nerve injury often leads to neuropathic pain. Although ketamine and pregabalin are first line options for the treatment of neuropathic pain, their clinical application is limited due to side effects such as sedation, dizziness and somnolence. We designed this study to determine whether the intrathecal (i.t.) co-treatment with ketamine and pregabalin at sub-effective low doses would elicit a sufficient pain relief without producing side effect in a neuropathic pain mouse model. At day 7 after chronic constriction injury (CCI) of sciatic nerve, dose dependent effects of i.t. ketamine (3, 10, 30, 100 µg) or i.t. pregabalin (10, 30, 100 µg) on mechanical allodynia and thermal hyperalgesia were measured. For combination treatment, 3 or 10 µg of ketamine and 30 µg of pregabalin were selected because these doses of drugs were not effective on neuropathic pain. Interestingly, combined i.t. treatment groups (ketamine 3 µg+pregabalin 30 µg and ketamine 10 µg+pregabalin 30 µg) produced strong analgesia on neuropathic pain although these doses of ketamine and pregabalin alone are not effective. Moreover, rota rod test revealed that normal motor function was not affected by combined treatment while i.t. ketamine at doses above 10 µg showed a significant motor dysfunction. Results of this study suggested that i.t. co-treatment with ketamine and pregabalin at sub-effect low doses may be a useful therapeutic method for the treatment of neuropathic pain patients.

Intrathecal ketamine and pregabalin at sub-effective doses synergistically reduces neuropathic pain without motor dysfunction in mice.

This study was designed to determine the antinociceptive effect and related neuronal mechanism of electroacupuncture (EA) on paclitaxel (PTX)-induced neuropathic pain in mice. PTX (4 mg/kg, i.p.) was administered once a day for 5 consecutive days to induce neuropathic pain. EA stimulation (2 mA, 2 Hz, 30 min) was applied at the ST36 acupoint bilaterally once in every 2 days. Repeated EA stimulation significantly attenuated PTX-induced mechanical allodynia and thermal hyperalgesia. In a separate set of experiment, the antinociceptive effect of a single EA stimulation 8 days after PTX treatment was reduced by intrathecal pretreatment with naloxone (opioid receptor antagonist), idazoxan (alpha2-adrenoceptor antagonist) or propranolol (beta-adrenoceptor antagonist), but not prazosin (alpha1-adrenoceptor antagonist). Moreover, EA remarkably suppressed the PTX-enhanced phosphorylation of the NMDA receptor NR2B subunit in the spinal dorsal horn, and intrathecal pretreatment of naloxone, idazoxan (IDA) or propranolol blocked the effect of EA. In conclusion, EA stimulation at the ST36 acupoint significantly diminished PTX-induced neuropathic pain in mice via the mediation of spinal opioid receptor, alpha2- and beta-adrenoceptors.

Analgesic effect of electroacupuncture on paclitaxel-induced neuropathic pain via spinal opioidergic and adrenergic mechanisms in mice.

The incidence of lung cancer has rapidly increased and cancer patients at a later cancer stage frequently suffer from unbearable cancer-associated pain. However, the pathophysiology of lung cancer pain has not been fully described due to a lack of appropriate animal models. This study was designed to determine the effect of Lewis lung carcinoma (LLC) cell inoculation on formalin-induced pain behavior and spinal Fos expression in C57BL/6 mice. LLC cells (1.5 × 10(5), 2.5 × 10(5), 3.0 × 10(5) or 5.0 × 10(5)) were inoculated into back or peri-sciatic nerve areas. Back area inoculation was adopted to determine the effect of cancer cell circulating factors and the peri-sciatic nerve area was used to evaluate the possible effects of cancer cell contacting and circulating factors on formalin-induced pain. At postinoculation day 7, LLC cell (5.0 × 10(5)) inoculations in both back and peri-sciatic nerve area significantly increased formalin-induced paw-licking time and spinal Fos expression over those in cell-media-inoculated (control) mice. Enhanced pain behavior and spinal Fos expression were significantly suppressed by ibuprofen pretreatment (250 mg/kg). The results of this study suggest that LLC cell circulating factors and inflammatory responses may be critical in enhancing pain sensation in the early stage of lung cancer cell inoculation.

Inoculation of Lewis lung carcinoma cells enhances formalin-induced pain behavior and spinal Fos expression in mice.

We have recently reported that repeated systemic treatments of extract from Corydalis yanhusuo alleviate neuropathic pain and levo-tetrahydropalmatine (l-THP) is one of active components from Corydalis. We designed this study to investigate antinociceptive effect of l-THP in acute and chronic pain models and related mechanism within the spinal cord. We found that intraperitoneal pretreatment with l-THP significantly inhibited the second phase of formalin-induced pain behavior. In addition, intrathecal as well as intraperitoneal pretreatment with l-THP reduced the mechanical allodynia (MA) induced by direct activation of sigma-1 receptor (Sig-1). In chronic constriction injury mice, these treatments remarkably suppressed the increase in MA and spinal phosphorylation of the NMDA receptor NR1 subunit expression on day 7 after surgery. Intrathecal treatment with l-THP combined with the Sig-1R antagonist, BD1047 synergistically blocked MA suggesting that l-THP modulates spinal Sig-1R activation. CatWalk gait analysis also supported that antinociceptive effect of l-THP as demonstrated by restoration of percentages of print area and single stance. Meanwhile, intrathecal pretreatment with naloxone, non-selective opioid receptor antagonist, did not affect the effect of l-THP. In conclusion, these results demonstrate that l-THP possesses antinociceptive effects through spinal Sig-1R mechanism and may be a useful analgesic in the management of neuropathic pain.

Antinociceptive Profile of Levo-tetrahydropalmatine in Acute and Chronic Pain Mice Models: Role of spinal sigma-1 receptor.

Scalding burn injuries can occur in everyday life but occur more frequently in young children. Therefore, it is important to develop more effective burn treatments.

Bee venom reduces burn-induced pain via the suppression of peripheral and central substance P expression in mice.

Although emerging evidence shows that angiotensin converting enzyme (ACE) is associated with pain, it is not clear whether inhibition of ACE could affect to nociceptive transmission and which mediators are involved in this process. Here we investigated whether administration of the ACE inhibitors, captopril and enalapril increases the expression of substance P (SP) and whether this increase contributes to the induction of mechanical allodynia in mice. ACE was expressed in the lumbar dorsal root ganglion (DRG) and the superficial dorsal horn (SDH) region of the spinal cord in mice. Either intraperitoneal or intrathecal administration of the ACE inhibitors, captopril and enalapril for 10 days significantly increased the paw withdrawal frequency to innocuous mechanical stimuli and the levels of SP in both the lumbar DRG and the SDH region of the spinal cord dorsal horn. In addition, intraperitoneal administration of the SP receptor (neurokinin-1 receptor) antagonist, L-733,060 suppressed mechanical allodynia that was induced by pretreatment of captopril and enalapril. Intraplantar administration of SP for 3 days induces mechanical allodynia, and this effect was reduced by exogenous ACE administration. These findings demonstrate that inhibition of ACE increases the levels of SP in both the lumbar DRG and spinal cord dorsal horn, ultimately contributing to the induction of mechanical allodynia in mice.

Jae-Gyun Choi

Department of Physiology and Medical Science,
College of Medicine and Brain Research Institute

Chungnam National University

Automated Gait Analysis in Mice with Chronic Constriction Injury

Burn Injury-Induced Pain and Depression-Like Behavior in Mice

Jae-Gyun Choi

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Physiology and Medical Science,College of Medicine and Brain Research Institute

Chungnam National University

Automated Gait Analysis in Mice with Chronic Constriction Injury

Burn Injury-Induced Pain and Depression-Like Behavior in Mice

Department of Physiology and Medical Science,
College of Medicine and Brain Research Institute