The Mechanical Antihyperalgesic Effect of Intrathecally Administered MPV-2426, a Novel α2-Adrenoceptor Agonist, in a Rat Model of Postoperative Pain

2000 ◽  
Vol 92 (6) ◽  
pp. 1740-1745 ◽  
Author(s):  
Tiina Onttonen ◽  
Antti Pertovaara
Keyword(s):  
Postoperative Pain ◽  
Rat Model ◽  
Spinal Pain ◽  
Mechanical Hyperalgesia ◽  
Lumbar Spinal Cord ◽  
Preoperative Treatment ◽  
Withdrawal Threshold ◽  
Plantar Aspect ◽  
Adrenoceptor Agonist ◽  
Alpha2 Adrenoceptor

Background MPV-2426 is a novel alpha2-adrenoceptor agonist developed for spinal pain therapy. It has proved to be effective in physiologic and neuropathic conditions. In the current study its effectiveness on mechanical hyperalgesia was assessed in a rat model of postoperative pain. Methods Rats with intrathecal catheters were anesthetized with pentobarbital, and a 1-cm incision was made in the plantar aspect of the foot and closed. During postoperative days 1 and 2 the antihyperalgesic effects induced by intrathecal MPV-2426, clonidine, and dexmedetomidine were determined by assessing the hind limb withdrawal threshold to calibrated von Frey hairs applied to the skin of the hind paw adjacent to the wound. Results MPV-2426 administered into the lumbar spinal cord produced a dose-dependent (0.3-10 microg) attenuation of the mechanical hyperalgesia, and this antihyperalgesic effect was completely reversed by yohimbine (1 mg/kg, subcutaneous), an alpha2-adrenoceptor antagonist. Dexmedetomidine (1-3 microg) produced an equipotent antihyperalgesic effect, whereas the effect of clonidine (1-10 microg) was markedly weaker. MPV-2426 (10 microg in 20 microl) administered adjacent to the wound did not produce any effect. Preoperative treatment with an antihyperalgesic dose of MPV-2426 did not prevent the development of hyperalgesia. Conclusions Intrathecal MPV-2426 dose-dependently attenuates postoperative hyperalgesia to mechanical stimulation because of an action on alpha2 adrenoceptors. Its antihyperalgesic action is as effective as that produced by dexmedetomidine and is considerably stronger than that produced by clonidine. However, preoperative treatment with MPV-2426 does not prevent the development of postoperative hyperalgesia.

Effect of Systemic and Intrathecal Morphine in a Rat Model of Postoperative Pain 

1997 ◽  
Vol 86 (5) ◽  
pp. 1066-1077 ◽  
Author(s):  
Peter K. Zahn ◽  
Dan Gysbers ◽  
Timothy J. Brennan
Keyword(s):  
Postoperative Pain ◽  
Rat Model ◽  
Intrathecal Morphine ◽  
Mechanical Stimulus ◽  
Mechanical Hyperalgesia ◽  
Response Frequency ◽  
Pain Behaviors ◽  
Withdrawal Threshold ◽  
Plantar Aspect ◽  
Investigational Agents

Background To learn more about persistent pain after an incision, a rat model for postoperative pain has been developed. To further evaluate this model, the authors examined the effect of intrathecal (IT) and subcutaneous (SC) morphine, effective for postoperative pain relief in patients, on pain behaviors immediately after surgery and 1 day after surgery. Methods Rats were anesthetized with halothane, and a 1-cm incision was made in the plantar aspect of the foot and closed. After recovery, the rats were placed on an elevated plastic mesh floor, and withdrawal threshold was determined using calibrated von Frey filaments (15-522 mN) applied from beneath the test cage to an area adjacent to the wound at the heel. Pain behaviors also were assessed using the response frequency to a nonpunctate mechanical stimulus and a cumulative pain score. Results Mechanical hyperalgesia and nonevoked pain behaviors were present on the day of surgery and 1 day after surgery. Administration of either SC (0.3-3.0 mg/kg) or IT (0.16-5.0 micrograms) morphine reversibly increased the withdrawal threshold. The response frequency to the nonpunctate stimulus and the nonevoked pain scores also were decreased by 3 mg/kg of SC or 5 micrograms of IT morphine. Naloxone (1 mg/kg) reversed morphine-produced hypoalgesia. Conclusion This is the first study to demonstrate that mechanical hyperalgesia to a nonpunctate stimulus occurs after a surgical incision in the rat. This rat model of postoperative has several similarities to postoperative patients: mechanical hyperalgesia to punctate and nonpunctate stimuli, nonevoked pain, and pain behaviors inhibited by SC and IT morphine. This model also may be useful for predicting analgesia by investigational agents for postoperative pain.

Comparison of Pre- versus Post-incision Administration of Intrathecal Bupivacaine and Intrathecal Morphine in a Rat Model of Postoperative Pain 

1997 ◽  
Vol 87 (6) ◽  
pp. 1517-1528 ◽  
Author(s):  
Timothy J. Brennan ◽  
Eric F. Umali ◽  
Peter K. Zahn
Keyword(s):  
Postoperative Pain ◽  
Rat Model ◽  
Intrathecal Morphine ◽  
Postoperative Pain Management ◽  
Preemptive Analgesia ◽  
Withdrawal Threshold ◽  
Beneficial Effects ◽  
Plantar Aspect ◽  
Incisional Pain ◽  
Saline Vehicle

Background Preclinical studies in experimental animals suggest that preemptive analgesia may improve postoperative pain management. The beneficial effects of preemptive analgesia appear less remarkable clinically. The purpose of this study is to examine the effect of pre- and post-incision administration of intrathecal bupivacaine and intrathecal morphine in a rat model for postoperative pain. Methods Rats with intrathecal catheters were anesthetized with halothane, and the surgical field was prepared. A saline vehicle or the test drug was administered 15 min before an incision was made in the plantar aspect of the hindpaw or after the incision was completed. After recovery, mechanical hyperalgesia to punctate and nonpunctate stimuli was measured. Rats were tested on the day of surgery for the first 5 h and each day for 6 days. Results In saline vehicle-treated rats, the median withdrawal threshold decreased from 522 mN to 54 mN or less, and the response frequency to pressure from application of the plastic disc increased from 0 +/- 0% to 96 +/- 12% or greater after incision. Hyperalgesia was persistent through 2 days after surgery and then gradually returned toward preincision values over the next 4 days. Pre- or postincision administration of either intrathecal morphine or intrathecal bupivacaine reduced hyperalgesia on the day of surgery; at all subsequent times, there were no differences between the saline vehicle groups and the drug treatment groups. There were never any significant differences between pre- and postincision treatments. Conclusions Early reduction in pain behaviors either by pre- or postincision management had no impact on subsequent measures of hyperalgesia in this model. These results agree with a number of clinical studies and suggest that incisional pain may be initiated and maintained differently than pain in other models.

Primary and Secondary Hyperalgesia in a Rat Model for Human Postoperative Pain 

1999 ◽  
Vol 90 (3) ◽  
pp. 863-872 ◽  
Author(s):  
Peter K. Zahn ◽  
Timothy J. Brennan
Keyword(s):  
Postoperative Pain ◽  
Rat Model ◽  
Radiant Heat ◽  
Mechanical Stimulus ◽  
Mechanical Stimuli ◽  
Secondary Hyperalgesia ◽  
Transitional Area ◽  
Withdrawal Threshold ◽  
Plantar Aspect ◽  
Primary Hyperalgesia

Background Previously, the authors developed and characterized a rat model for postoperative pain to learn more about pain produced by incisions. In this study, the responses to heat and mechanical stimuli were evaluated directly on or adjacent to the incision and at varying distances from the incision. Methods Rats were anesthetized with halothane and incisions were made at different locations in the plantar aspect of the foot. The response frequency to a blunt mechanical stimulus, the withdrawal threshold to von Frey filaments (15-522 mN), and the withdrawal latency to radiant heat were measured. Rats were tested before surgery, 2 h later, and then daily through postoperative day 9. Results After plantar incision, persistent hyperalgesia was observed immediately adjacent to or directly on the incision to punctate and blunt mechanical stimuli, respectively. The withdrawal threshold to punctate stimuli applied 1 cm from the incision was decreased through postoperative day 1. In a transitional area, between the distant and adjacent sites, the withdrawal threshold was intermediate and the duration of hyperalgesia was transient. Heat hyperalgesia was persistent but present when the stimulus was applied to the site of injury but not to a distant site. Conclusion Robust primary hyperalgesia to punctate and blunt mechanical stimuli was present. Hyperalgesia distant to the wound, or secondary hyperalgesia, occurred in response to punctate mechanical stimuli, was short-lived, and required greater forces. These results suggest that the most persistent pain behaviors in this model are largely primary hyperalgesia.

scholarly journals Restoring Spinal Noradrenergic Inhibitory Tone Attenuates Pain Hypersensitivity in a Rat Model of Parkinson’s Disease

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Lei-Fang Cao ◽  
Xiao-Yan Peng ◽  
Ya Huang ◽  
Bing Wang ◽  
Feng-Ming Zhou ◽  
...  
Keyword(s):  
Rat Model ◽  
Systemic Treatment ◽  
Lumbar Spinal Cord ◽  
Mechanical Hypersensitivity ◽  
Pain Hypersensitivity ◽  
Adrenoceptor Agonist ◽  
Novel Strategy ◽  
6 Hydroxydopamine ◽  
Lumbar Spinal ◽  
Inhibitory Tone

In the present study, we investigated whether restoring descending noradrenergic inhibitory tone can attenuate pain in a PD rat model, which was established by stereotaxic infusion of 6-hydroxydopamine (6-OHDA) into the bilateral striatum (CPu). PD rats developed thermal and mechanical hypersensitivity at the 4th week after surgery. HPLC analysis showed that NE content, but not dopamine or 5-HT, significantly decreased in lumbar spinal cord in PD rats. Additional noradrenergic depletion by injection of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) aggravated pain hypersensitivity in PD rats. At the 5th week after injection of 6-OHDA, systemic treatment with pharmacological norepinephrine (NE) precursor droxidopa (L-DOPS) orα2 adrenoceptor agonist clonidine significantly attenuated thermal and mechanical pain hypersensitivity in PD rats. Furthermore, application of norepinephrine (NE) and 5-hydroxytryptamine (5-HT) reuptake inhibitors duloxetine, but not 5-HT selective reuptake inhibitors sertraline, significantly inhibited thermal and mechanical pain hypersensitivity in PD rats. Systemic administration of Madopar (L-DOPA) or the D2/D3 agonist pramipexole slightly inhibited the thermal, but not mechanical, hypersensitivity in PD rats. Thus, our study revealed that impairment of descending noradrenergic system may play a key role in PD-associated pain and restoring spinal noradrenergic inhibitory tone may serve as a novel strategy to manage PD-associated pain.

scholarly journals Assessment of the Anti-Allodynic and Anti-Hyperalgesic Efficacy of a Glycine Transporter 2 Inhibitor Relative to Pregabalin, Duloxetine and Indomethacin in a Rat Model of Cisplatin-Induced Peripheral Neuropathy

Biomolecules ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 940
Author(s):  
Andy Kuo ◽  
Laura Corradini ◽  
Janet R. Nicholson ◽  
Maree T. Smith
Keyword(s):  
Peripheral Neuropathy ◽  
Rat Model ◽  
Mechanical Allodynia ◽  
Negative Impact ◽  
Mechanical Hyperalgesia ◽  
Essential Medicines ◽  
World Health ◽  
Lumbar Spinal Cord ◽  
Glycine Transporter ◽  
Glycine Transporter 2

Cisplatin, which is a chemotherapy drug listed on the World Health Organisation’s List of Essential Medicines, commonly induces dose-limiting side effects including chemotherapy-induced peripheral neuropathy (CIPN) that has a major negative impact on quality of life in cancer survivors. Although adjuvant drugs including anticonvulsants and antidepressants are used for the relief of CIPN, analgesia is often unsatisfactory. Herein, we used a rat model of CIPN (cisplatin) to assess the effect of a glycine transporter 2 (GlyT2) inhibitor, relative to pregabalin, duloxetine, indomethacin and vehicle. Male Sprague-Dawley rats with cisplatin-induced mechanical allodynia and mechanical hyperalgesia in the bilateral hindpaws received oral bolus doses of the GlyT2 inhibitor (3–30 mg/kg), pregabalin (3–100 mg/kg), duloxetine (3–100 mg/kg), indomethacin (1–10 mg/kg) or vehicle. The GlyT2 inhibitor alleviated both mechanical allodynia and hyperalgesia in the bilateral hindpaws at a dose of 10 mg/kg, but not at higher or lower doses. Pregabalin and indomethacin induced dose-dependent relief of mechanical allodynia but duloxetine lacked efficacy. Pregabalin and duloxetine alleviated mechanical hyperalgesia in the bilateral hindpaws while indomethacin lacked efficacy. The mechanism underpinning pain relief induced by the GlyT2 inhibitor at 10 mg/kg is likely due to increased glycinergic inhibition in the lumbar spinal cord, although the bell-shaped dose–response curve warrants further translational considerations.

scholarly journals Multi-pronged neuromodulation intervention engages the residual motor circuitry to facilitate walking in a rat model of spinal cord injury

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marco Bonizzato ◽  
Nicholas D. James ◽  
Galyna Pidpruzhnykova ◽  
Natalia Pavlova ◽  
Polina Shkorbatova ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Rat Model ◽  
Stress Responses ◽  
Learning Algorithm ◽  
Lumbar Spinal Cord ◽  
Cord Injury ◽  
Potential Synergy ◽  
Lumbar Spinal ◽  
Deep Brain

AbstractA spinal cord injury usually spares some components of the locomotor circuitry. Deep brain stimulation (DBS) of the midbrain locomotor region and epidural electrical stimulation of the lumbar spinal cord (EES) are being used to tap into this spared circuitry to enable locomotion in humans with spinal cord injury. While appealing, the potential synergy between DBS and EES remains unknown. Here, we report the synergistic facilitation of locomotion when DBS is combined with EES in a rat model of severe contusion spinal cord injury leading to leg paralysis. However, this synergy requires high amplitudes of DBS, which triggers forced locomotion associated with stress responses. To suppress these undesired responses, we link DBS to the intention to walk, decoded from cortical activity using a robust, rapidly calibrated unsupervised learning algorithm. This contingency amplifies the supraspinal descending command while empowering the rats into volitional walking. However, the resulting improvements may not outweigh the complex technological framework necessary to establish viable therapeutic conditions.

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