Practice With the Experts: Strategies for Pain Management With Botulinum Neurotoxin Therapy

1. Practice With the Experts: Strategies for Pain Management With Botulinum Neurotoxin Therapy

2. Botulinum Toxin Timeline anaerobic, exotoxins botulinum-flaccid paralysis, PNS cholinergic terminals, flac tetanus-rigid paralysis, CNS ? flaccid paralysis due to cholinergic denervation-muscle relaxation toxin property exploited in using BOTOX as therapeutic agent anaerobic, exotoxins botulinum-flaccid paralysis, PNS cholinergic terminals, flac tetanus-rigid paralysis, CNS ? flaccid paralysis due to cholinergic denervation-muscle relaxation toxin property exploited in using BOTOX as therapeutic agent

3. Botulinum Toxin Structural Complex Seven Serotypes A, B, C1, D, E, F, G Complex Size Varies Complex includes neurotoxin protein and may include: (NTNH) nonhemagglutinin protein +/- (HA) hemagglutinin protein anaerobic, exotoxins botulinum-flaccid paralysis, PNS cholinergic terminals, flac tetanus-rigid paralysis, CNS ? flaccid paralysis due to cholinergic denervation-muscle relaxation toxin property exploited in using BOTOX as therapeutic agent anaerobic, exotoxins botulinum-flaccid paralysis, PNS cholinergic terminals, flac tetanus-rigid paralysis, CNS ? flaccid paralysis due to cholinergic denervation-muscle relaxation toxin property exploited in using BOTOX as therapeutic agent

4. Botulinum Toxin Type A Has High Affinity For The Neuromuscular Junction Local, Temporary Muscle Relaxation Heavy chain binding domain is shown in the green ribbon. It responsible for binding to it’s serotype specific receptor/acceptor on the target cell The domain shown in red mediates translocation: aids in transversing the membrane, and allowing for the expression of the light chain to outside of the vesicle Light chain shown in yellow. The effect of BoNT depends on the enzymatic action of the light chain (very specific peptidase with a specific target. This region is unique for each serotype) Once active, the toxin produces an effect that is: Local– effective within a predictable radius at the site of injection Temporary - lasting 3 months (rule of 3’s starts in three days peak effect at three weeks lasts 3 months) Muscle relaxation- when we block acetylcholine release at the end plate of the motor neuron Transition: Now let’s look at the MOA of the toxin Heavy chain binding domain is shown in the green ribbon. It responsible for binding to it’s serotype specific receptor/acceptor on the target cell The domain shown in red mediates translocation: aids in transversing the membrane, and allowing for the expression of the light chain to outside of the vesicle Light chain shown in yellow. The effect of BoNT depends on the enzymatic action of the light chain (very specific peptidase with a specific target. This region is unique for each serotype) Once active, the toxin produces an effect that is: Local– effective within a predictable radius at the site of injection Temporary - lasting 3 months (rule of 3’s starts in three days peak effect at three weeks lasts 3 months) Muscle relaxation- when we block acetylcholine release at the end plate of the motor neuron Transition: Now let’s look at the MOA of the toxin

5. To view the Mechanism of Action Video The Window Media video file ‘BonT-A-MechofAction_2005.wmv’ must be located in the same folder as this PowerPoint File. This file can be downloaded from the Scientific Resource Center (http://scientificresourcecenter.net)To view the Mechanism of Action Video The Window Media video file ‘BonT-A-MechofAction_2005.wmv’ must be located in the same folder as this PowerPoint File. This file can be downloaded from the Scientific Resource Center (http://scientificresourcecenter.net)

6. Vesicle Docking Protein Target SitesFor Botulinum Toxin Serotypes The different serotypes interfere with synaptic transmission by acting upon different intracellular proteins required for vesicle fusion with the neuronal membrane. This drawing depicts a synaptic vesicle near the plasma membrane and a hypothetical model of the synaptic fusion complex. The soluble proteins involved are not shown in this illustration. Various intracellular proteins, shown as alpha helices, facilitate exocytosis. Arrows indicate the points at which botulinum toxins cleave these proteins (for illustration purposes only). The various botulinum toxin serotypes cleave different proteins or cleave the same protein at different sites. Tetanus toxin and botulinum toxin type B cleave the same protein (VAMP/synaptobrevin) at the same site. Note to presenter: The coiled proteins shown in this figure are for illustration purposes only. Botulinum toxins can only access their target proteins when the protein is extended (ie, not in the coiled form that is shown on this slide). The different serotypes interfere with synaptic transmission by acting upon different intracellular proteins required for vesicle fusion with the neuronal membrane. This drawing depicts a synaptic vesicle near the plasma membrane and a hypothetical model of the synaptic fusion complex. The soluble proteins involved are not shown in this illustration. Various intracellular proteins, shown as alpha helices, facilitate exocytosis. Arrows indicate the points at which botulinum toxins cleave these proteins (for illustration purposes only). The various botulinum toxin serotypes cleave different proteins or cleave the same protein at different sites. Tetanus toxin and botulinum toxin type B cleave the same protein (VAMP/synaptobrevin) at the same site. Note to presenter: The coiled proteins shown in this figure are for illustration purposes only. Botulinum toxins can only access their target proteins when the protein is extended (ie, not in the coiled form that is shown on this slide).

7. The Basis for Botulinum Toxin Use in Pain Pain improvement was noted in initial dystonia and spasticity studies Brin 1986 series: cervical dystonia: 64% motor improvement 74% pain improvement

8. Treatment Approaches to Muscle Pain Interrupt pain/spasm cycle Treat underlying conditions and associated symptoms (e.g., insomnia) Work on maladaptive behaviors: psychotherapy Physical therapy Massage/myofascial release Manipulation techniques Spray and stretch Heat/cold treatments Surface stimulation techniques: TENS, etc Relaxation/biofeedback techniques Oral medications Acupuncture and acupressure Trigger-point injections Botulinum toxin injections Surgery Treatment Approaches to Muscle Pain Current treatments for muscle-associated pain are aimed at interrupting the pain/spasm cycle. Treat any underlying conditions associated with symptoms (eg, insomnia), and possibly correct maladaptive behavior with psychotherapy. Recondition and strengthen the involved musculature through intensive physical therapy, massage, myofascial release, or manipulation techniques. Improve pain and range of motion with spray and stretch, heat/cold treatments, or surface stimulation techniques such as TENS units and relaxation/biofeedback exercises as well as acupuncture/acupressure. Utilize pharmacologic therapies (muscle relaxants, antispasmodics, and narcotics) and trigger-point injection with a numbing agent such as lidocaine, with or without a steroid. A patient with chronic pain will generally try various methods of treatment, but unfortunately, this may not be enough. For more than 10 years, botulinum toxin type A—a potent, focal antispasmodic—has been relieving muscle-associated pain. Using BoNT/A therapy early on in the treatment paradigm may prevent the chronic nature of muscle pain often experienced by patients. Treatment Approaches to Muscle Pain Current treatments for muscle-associated pain are aimed at interrupting the pain/spasm cycle. Treat any underlying conditions associated with symptoms (eg, insomnia), and possibly correct maladaptive behavior with psychotherapy. Recondition and strengthen the involved musculature through intensive physical therapy, massage, myofascial release, or manipulation techniques. Improve pain and range of motion with spray and stretch, heat/cold treatments, or surface stimulation techniques such as TENS units and relaxation/biofeedback exercises as well as acupuncture/acupressure. Utilize pharmacologic therapies (muscle relaxants, antispasmodics, and narcotics) and trigger-point injection with a numbing agent such as lidocaine, with or without a steroid. A patient with chronic pain will generally try various methods of treatment, but unfortunately, this may not be enough. For more than 10 years, botulinum toxin type A—a potent, focal antispasmodic—has been relieving muscle-associated pain. Using BoNT/A therapy early on in the treatment paradigm may prevent the chronic nature of muscle pain often experienced by patients.

9. Botulinum Neurotoxin Mechanism Nociceptors/pain pathway? Muscle/skin A delta and C fibers (group III and IV) Mechano/chemonociceptors Glands Inhibition of parasympathetic nerve-induced secretions Muscle Alpha/Gamma motor neuron inhibition Ia afferent reduction BoNT Mechanism BoNT may also act directly or indirectly on nociceptors that affect transmission of sensory signals via A delta and C gamma fibers, as well as impact detection of sensory signals via mechanoreceptors and chemonociceptors. BoNT Mechanism BoNT may also act directly or indirectly on nociceptors that affect transmission of sensory signals via A delta and C gamma fibers, as well as impact detection of sensory signals via mechanoreceptors and chemonociceptors.

10. Reduction of Neurotransmission and Reduction of Neck Pain in Cervical Dystonia

11. Are the Effects of BTX on Muscle Only? 1980’s: Clinical observations after BoNT injections for CD Benefits on pain outlasted posture, suggesting a dual effect Brin, et al., 1986; Jankovic et al., 1990 1990’s: Does the anti-nociceptive effects of BTX, outlast it’s effects on posture (muscle)? - Formal investigation into these clinical observations First, & Tarsy;1998; Tarsy & First, 1999; Relja et al., 2000 First look at pain specifically which followed observations Initial thinking in patients with cervical dystonia was that repetitive muscle contractions caused the movement disorder and postural abnormalities also caused the pain Local Pain: neck & shoulder Radicular Pain: down back & arm Clinical observations after BoNT injections suggested dual mechanism of action because: Pain relief before decrease in movement Pain relief in those who did not get much decrease in movement disorder First look at pain specifically which followed observations Initial thinking in patients with cervical dystonia was that repetitive muscle contractions caused the movement disorder and postural abnormalities also caused the pain Local Pain: neck & shoulder Radicular Pain: down back & arm Clinical observations after BoNT injections suggested dual mechanism of action because: Pain relief before decrease in movement Pain relief in those who did not get much decrease in movement disorder

12. How Does Botulinum Toxin Work in Alleviating Pain? Pain relief observed with further botulinum toxin type A (BoNT/A) utilization Migraine prophylaxis observed Some physicians “follow the pain” Others follow a fixed dose/fixed site paradigm Mechanism? How Does Botulinum Toxin Type A Work in Alleviating Pain? Pain relief was one of the first noted benefits of BoNT/A therapy during early research in cervical dystonia and hemifacial spasm. Growing evidence of efficacy within the migraine arena has shown that BoNT/A has a more important role in the treatment of painful conditions. The question is how this pain relief mechanistically occurs. It could be due to relaxation of pathologic muscle spasm through the blockage of acetylcholine release. It is believed that BoNT/A may have an effect on the muscle spindle firing and Ia afferent signals to the CNS, or it could have a direct effect on the spinal cord and the CNS, or it could be a combination of these mechanisms working together. How Does Botulinum Toxin Type A Work in Alleviating Pain? Pain relief was one of the first noted benefits of BoNT/A therapy during early research in cervical dystonia and hemifacial spasm. Growing evidence of efficacy within the migraine arena has shown that BoNT/A has a more important role in the treatment of painful conditions. The question is how this pain relief mechanistically occurs. It could be due to relaxation of pathologic muscle spasm through the blockage of acetylcholine release. It is believed that BoNT/A may have an effect on the muscle spindle firing and Ia afferent signals to the CNS, or it could have a direct effect on the spinal cord and the CNS, or it could be a combination of these mechanisms working together.

13. Reduction of Neurotransmission and Reduction of Pain in Headache & Inflammatory Pain Conditions

14. Regulated ExocytosisMultiple neurotransmitters/neuropeptidesreleased from vesicle Regulated Exocytosis It is well documented that BoNT produces its muscle relaxation effect by blocking the release of acetylcholine within the alpha motor neuron. It is the same vesicular release mechanism involving the SNARE complex of proteins to form a “pore,” allowing the release of vesicle contents that are utilized throughout the body. This same mechanism allows the release of nociceptive neuropeptides such as substance P and glutamate, which are both involved in the chronic inflammatory pain response. Regulated Exocytosis It is well documented that BoNT produces its muscle relaxation effect by blocking the release of acetylcholine within the alpha motor neuron. It is the same vesicular release mechanism involving the SNARE complex of proteins to form a “pore,” allowing the release of vesicle contents that are utilized throughout the body. This same mechanism allows the release of nociceptive neuropeptides such as substance P and glutamate, which are both involved in the chronic inflammatory pain response.

15. In-Vitro Substance- P InhibitionDorsal Root Ganglion Model: Welch et al., 2001 Insert capsaicin picture.Insert capsaicin picture.

16. Botulinum Toxin Inhibits Substance P Release from Dorsal Root Ganglia Neuron in Vitro Embryonic rat dorsal root ganglion (DRG) cells sensitive to botulinum toxin/A, C, F, B Substance P release inhibited Vesicle fusion inhibited by botulinum toxins

17. In-Vitro Inhibition of cGRP Secretion From Trigeminal Nerve Cells Newborn Rat Migraine Model: Durham, et al., 2003 Research on inflammation, migraine & TMJ disorder Primary cultures of rat trigeminal ganglion: In-vitro model to assess sensory nerve c-fiber activity Assess effects of BoNT/A pretreatment on resting (basal rate) and active (stimulated) release of cGRP Calcitonin gene regulated peptide (cGRP): a neuropeptide involved in the pathophysiology of migraine Can BoNT/A inhibit release of cGRP from C-fibers of sensory nerves? To determine the effect of botulinum toxin type A (BoNT/A) on calcitonin gene-related peptide (cGRP) secretion from cultured trigeminal ganglia neurons. The ability of botulinum toxins to cause muscle paralysis by blocking acetylcholine release and alpha motor neuron at the neuromuscular junction is well known. Previous studies and clinical observations have failed to demonstrate sensory changes related to botulinum toxins or the disease of botulism. However, recent studies have suggested that BoNT/A injected into pericranial muscles may have a prophylactic benefit in migraine. This observation has renewed the debate of a mechanism of sensory inhibition mediated by BoNT/A. To determine the effect of botulinum toxin type A (BoNT/A) on calcitonin gene-related peptide (cGRP) secretion from cultured trigeminal ganglia neurons. The ability of botulinum toxins to cause muscle paralysis by blocking acetylcholine release and alpha motor neuron at the neuromuscular junction is well known. Previous studies and clinical observations have failed to demonstrate sensory changes related to botulinum toxins or the disease of botulism. However, recent studies have suggested that BoNT/A injected into pericranial muscles may have a prophylactic benefit in migraine. This observation has renewed the debate of a mechanism of sensory inhibition mediated by BoNT/A.

18. BoNT/A Effects onKCl-Stimulated cGRP release No BoNT/A KCl, IFC or Cap stimulus 4-5 fold increase in cGRP released BoNT/A pretreatment overnight cGRP KCl-stimulated release: Dose dependent inhibition Graph on Left: Effect of BoNT/A on unstimulated cGRP release. The relative amount of cGRP secreted into the culture media in 1 h from untreated control cells (CON) or cells treated for 24 hrs with 1.3 or 3.1 units of botulinum toxin type A (BoNT) or vehicle (VEH). The mean basal rate of cGRP release was 34 +/- 4 pg/h per well (SE, n = 6). The secretion rate for each condition was normalized to the basal rate for each well. These concentrations of BoNT/A are well within or below the range of tissue concentration easily achieved with local injection of BoNT/A. Incubation of the cultures with toxin for 24, 6, or even 3 hrs was very effective at repressing stimulated cGRP secretion when compared to control values. Graph on Right: Effect of BoNT/A on KCl-stimulated cGRP release. The relative amount of cGRP secreted into the culture media per h from untreated control cells (CON) or cells pretreated for 24 h in the presence of vehicle (VEH) or botulinum toxin (BoNT) prior to addition of 60 mM KCl. The mean basal rate of cGRP release was 29 +/- 2 pg/h per well (SE, n = 6). The secretion rate for each condition was normalized to the basal rate for each well. The means and the SE from four independent experiments are shown. *p< 0.01 when compared with untreated control levels and #p< 0.01 when compared with KCl-treated levels. Graph on Left: Effect of BoNT/A on unstimulated cGRP release. The relative amount of cGRP secreted into the culture media in 1 h from untreated control cells (CON) or cells treated for 24 hrs with 1.3 or 3.1 units of botulinum toxin type A (BoNT) or vehicle (VEH). The mean basal rate of cGRP release was 34 +/- 4 pg/h per well (SE, n = 6). The secretion rate for each condition was normalized to the basal rate for each well. These concentrations of BoNT/A are well within or below the range of tissue concentration easily achieved with local injection of BoNT/A. Incubation of the cultures with toxin for 24, 6, or even 3 hrs was very effective at repressing stimulated cGRP secretion when compared to control values. Graph on Right: Effect of BoNT/A on KCl-stimulated cGRP release. The relative amount of cGRP secreted into the culture media per h from untreated control cells (CON) or cells pretreated for 24 h in the presence of vehicle (VEH) or botulinum toxin (BoNT) prior to addition of 60 mM KCl. The mean basal rate of cGRP release was 29 +/- 2 pg/h per well (SE, n = 6). The secretion rate for each condition was normalized to the basal rate for each well. The means and the SE from four independent experiments are shown. *p< 0.01 when compared with untreated control levels and #p< 0.01 when compared with KCl-treated levels.

19. In-Vivo Antinociceptive Behavior InhibitionRat Formalin Model:Aoki 2003 BoNT/A (Allergan) injected subplantar at -5 days The plantar surface of the right hindpaw injected, sc, with 50 ?l of 5% formalin Evaluate the number of formalin-evoked flinching responses and the time spent licking the injected paw during time intervals The early response 0-5 min and late phase 15-60 min

20. BoNT/A (s.c.) Reduced Formalin-Induced Pain (5 Day Pretreatment) Lifting/Licking Time (sec): Immediately after formalin injection the Lifting/Licking time was recorded in 5-min intervals for 1 h. Behaviors during each phase are presented as the sum of the total number of seconds spent L/L during that phase.Lifting/Licking Time (sec): Immediately after formalin injection the Lifting/Licking time was recorded in 5-min intervals for 1 h. Behaviors during each phase are presented as the sum of the total number of seconds spent L/L during that phase.

21. Subcutaneous Botulinum Toxin/A (- 5 d) Reduced Formalin-induced Glutamate Release in the Rat Paw

22. Subcutaneous BoNT/A (Allergan) reduced the Formalin-induced activity in phase II Control have three non responder in phase II, took out. So n from 11 to 8Control have three non responder in phase II, took out. So n from 11 to 8

23. SummaryFormalin Inflammatory Pain Model BoNT/A s.c., 5 day pretreatment required Inhibition of pain response (second phase) Response maintained from single treatment No obvious motor weakness or weight loss BoNT/A reducing C and A delta fiber activity? Reduced glutamate, edema

24. Conclusions and Clinical Relevance in Pain The next set of slides are to summarize: #30 – 20+ years of supportive preclinical data #31 – describe site of action/interaction in the inflammation and pain pathway #32 - discuss the underlying factor unifying the hypothesis (SNAP-25) #33 – Conclusions #34 – References slide to show in background while entertaining questionsThe next set of slides are to summarize: #30 – 20+ years of supportive preclinical data #31 – describe site of action/interaction in the inflammation and pain pathway #32 - discuss the underlying factor unifying the hypothesis (SNAP-25) #33 – Conclusions #34 – References slide to show in background while entertaining questions

25. Inhibition of Neuropeptide Release: In-Vitro and In-Vivo Support 1981-2000: 30+ studies EXAMPLE 1 (Can use as a summary slide in situations where going through the pre-clinical is not necessary)In order to validate the hypothesis that BoNT's have the potential therapeutic properties to block inflammatory cascade pathways, experiments were undertaken using a classical model for inflammation. The rat foot paw model of inflammation was utilized in which carrageenan is employed to evoke the inflammatory response following subcutaneous administration. The results of these experiments showed that BONT produced significant antagonism of the profound carrageenan-evoked inflammation. Methods/Materials Type A lyophilized Clostridium botulinum toxin type A (BOTOX.RTM.) produced by Allergan, Inc., Irvine, Calif. was obtained for the experiment (lot #CGB 001, Exp. Date; Feb 98). A total of 11 white male Wistar rats (150-200 g) where 10 were pretreated by injection into the left ankle (test side) of 50 .mu.l of 30 LD50 units of Hall Strain Clostridium botulinum toxin Type A, resuspended in sterile 0.9% saline solution. The number 11 rat was administered the same above dose but was injected I.P., in order to assess the potency of the toxin. Observations after 24 hours confirmed the potency and also, the left ankle showed hallmark signs of paralysis. The right ankle of each of the 10 pretreated rats were injected with sterile saline alone and used as the control side. Upon paralysis, the 10 animals were challenged with 50 .mu.l of 0.1% carrageenan solution, injected into the left and right footpads. Carrageenan is a compound that initiates extreme inflammation almost immediately upon injection. The results of published data show that this response has a significant neurogenic component. Readings were performed by a standardized volumetric fluid displacement analysis which measures the degree of inflammation compared to baseline; taken at baseline, one and three hours. Results Statistical analysis was performed using Sigma Stat (Jandell Scientific) software. Data was confirmed statistically and passed the test for normalization of data and therefore a paired t-test was calculated for the 1 and 3 hour readings, with n=10. At 1 hour the data was not significant, with a p-value of 0.38, however, at 3 hours, the data revealed an unexpected 30% reduction in inflammation with a p-value of <0.001. These data confirm that BoNT have an effect on blocking the inflammation mediated by the above mentioned neuropeptides, in particular but not limited to, substance P (SP), and calcitonin related gene product (cGRP), via but not limited to, sensory and efferent nerve pathways; an antidromic response. Discussion The rat foot paw model for inflammation is a general model used to screen anti-inflammatory compounds. Thus, this provides a good test of the basic hypothesis that BoNTs can antagonize inflammation. This also provides a challenging test as carrageenan-evoked inflammation involves profound stimulation of inflammation not just involving the proposed mechanisms antagonized by BoNTs. The fact that BoNT produced significant antagonism of this extreme inflammatory response argues strongly for the hypothesis embodied in this invention. In the normal course of neurogenic inflammatory disease such as rheumatoid arthritis, the onset of inflammation is more gradual and therefore antagonism of inflammation by BoNT would be expected to be greater, particularly in the case of rheumatoid arthritis. EXAMPLE 1 (Can use as a summary slide in situations where going through the pre-clinical is not necessary)In order to validate the hypothesis that BoNT's have the potential therapeutic properties to block inflammatory cascade pathways, experiments were undertaken using a classical model for inflammation. The rat foot paw model of inflammation was utilized in which carrageenan is employed to evoke the inflammatory response following subcutaneous administration. The results of these experiments showed that BONT produced significant antagonism of the profound carrageenan-evoked inflammation.

26. Pre-clinical Research Provides the Common Link Underlying the Effects of BTX The highly precise targeting of BTX-A for its substrate SNAP-25 is the common link underlying BTXs versatility of effects in multiple conditions: Supporting the hypothesis SNARE proteins involved in vesicle mediated exocytosis Muscle contraction (release of ACh) requires intact SNAP-25 BTX-A substrate is SNAP-25 and therefore cleaves SNAP-25 BTX inhibits Ach release in muscle and autonomic system Clinically, following BTX-A treatment in painful muscle disorders, a temporal difference in the relaxation and pain relief effects were observed BTX-A must have independent effects on muscle relaxation and pain Mediators of pain/inflammation are released by sensory nerves via vesicle and SNARE mediated exocytosis BTX-A cleaves SNAP-25 at NMJ and within these sensitized neurons; thus having a triple effect SPEAKER NOTES CLICK at the NMJ, mus spindles, autonomic and on sensory nerves. Click It is SNAP-25, a requisite for vesicular docking and release that underlies these different systems that helps to explain how BTX can have an effect on various conditions. CLICK The highly precise targeting of BTX-A for its substrate SNAP-25 is the common link underlying BTXs versatility of effects in multiple conditions: Supporting the hypothesis SNARE proteins involved in vesicle mediated exocytosis Muscle contraction (release of ACh) requires intact SNAP-25 BTX-A substrate is SNAP-25 and therefore cleaves SNAP-25 BTX inhibits Ach release in muscle and autonomic system Clinically, following BTX-A treatment in painful muscle disorders, a temporal difference in the relaxation and pain relief effects were observed BTX-A must have independent effects on muscle relaxation and pain Mediators of pain/inflammation are released by sensory nerves via vesicle and SNARE mediated exocytosis BTX-A cleaves SNAP-25 at NMJ and within these sensitized neurons; thus having a triple effect SPEAKER NOTES CLICK at the NMJ, mus spindles, autonomic and on sensory nerves. Click It is SNAP-25, a requisite for vesicular docking and release that underlies these different systems that helps to explain how BTX can have an effect on various conditions. CLICK

27. Peripheral Sensitization Leads to Central Sensitization

28. Botulinum Toxins May Prevent Peripheral Sensitization and Central Sensitization

29. Conclusions Pain Relief: Subcutaneous or IM botulinum toxin/A may inhibit the peripheral sensitization by inhibiting local neurotransmitter release Peripheral effect of botulinum toxin may exert an indirect effect on the CNS Indirect reduction of central sensitization

30. References Vesicle-dependent exocytosis of neuropeptides Capsaicin-induced substance P release inhibited from eDRG Purkiss J et al. Biochem Pharmacol 2000;59(11):1403-1406. Welch MJ et al. Toxicon 2000;38(2):245-258. Neuropeptide Substance P and ACH release inhibited Ishikawa H et al. Jpn J Ophthalmol 2000;44(2):106-109. Inflammatory pain-rat formalin model Dose-dependent inhibition of formalin-induced inflammatory pain without muscle weakness Aoki KR. Headache 2003;43(s1):9-15. Inflammation, migraine, and TMJ model Inhibition of cGRP Secretion From Trigeminal Nerve Cells Durham PL et al. Headache 2004;44(1):35. Summary: BoNT/A Effect on Nociceptive Nerves Neuropeptide release was reported to be inhibited by botulinum toxin (types A, B, C1, F) treatment in vitro from embryonic rat dorsal root ganglia neurons and from isolated rabbit iris sphincter and dilatory muscles. (Purkiss et al, 2000; Welch et al, 2000; Ishikawa et al, 2000) In vitro release of acetylcholine and substance P (but not norepinephrine) from the rabbit ocular tissue was also inhibited with BoNT/A. Based on the in vitro and limited in vivo data, it can be hypothesized that botulinum toxin treatment may reduce the local release of nociceptive neuropeptides from either cholinergic neurons or from C or A delta fibers in vivo. This reduced neuropeptide release could prevent the local sensitization of nociceptors and thus reduce the perception of pain. A reduction of nociceptive signals from the periphery could then reduce the central sensitization associated with chronic pain. At the Society for Neuroscience meeting, it was reported that preclinical investigation on the local antinociceptive efficacy of BoNT/A (Allergan) demonstrated a dose-dependent inhibition of formalin-induced inflammatory pain without muscle weakness. (Cui et al, 2000) Summary: BoNT/A Effect on Nociceptive Nerves Neuropeptide release was reported to be inhibited by botulinum toxin (types A, B, C1, F) treatment in vitro from embryonic rat dorsal root ganglia neurons and from isolated rabbit iris sphincter and dilatory muscles. (Purkiss et al, 2000; Welch et al, 2000; Ishikawa et al, 2000) In vitro release of acetylcholine and substance P (but not norepinephrine) from the rabbit ocular tissue was also inhibited with BoNT/A. Based on the in vitro and limited in vivo data, it can be hypothesized that botulinum toxin treatment may reduce the local release of nociceptive neuropeptides from either cholinergic neurons or from C or A delta fibers in vivo. This reduced neuropeptide release could prevent the local sensitization of nociceptors and thus reduce the perception of pain. A reduction of nociceptive signals from the periphery could then reduce the central sensitization associated with chronic pain. At the Society for Neuroscience meeting, it was reported that preclinical investigation on the local antinociceptive efficacy of BoNT/A (Allergan) demonstrated a dose-dependent inhibition of formalin-induced inflammatory pain without muscle weakness. (Cui et al, 2000)