Botulinum Neurotoxin Type A Research Articles

Fusion of Golgi-derived vesicles mediated by SNAP-25 is essential for sympathetic neuron outgrowth but relatively insensitive to botulinum neurotoxins in vitro.

Sympathetic neurons ramify to innervate multiple cells in target tissues. In compartmentalized cultures of rat superior cervical ganglion neurons, cleavage of synaptosomal-associated protein of Mr =25000 (SNAP-25) in neurites exposed to botulinum neurotoxin typeA (BoNT/A) arrested their growth and collapsed interstitial branches, but this required large, nonclinical doses. A protease-inactive mutant proved ineffective, confirming involvement of SNAP-25 in neurite extension and arborization. BoNT/C1 acted like BoNT/A, but BoNT/E caused only mild inhibition, likely due to transient SNAP-25 proteolysis. Near-total lack of susceptibility to BoNT/B or BoNT/D revealed that vesicle-associated membrane protein (VAMPs) isoforms 1-3 are not essential. Neurite length was not reduced when either BoNT/A or BoNT/C1 was applied to the somata, with no detrimental effect on neuron viability being observed. Treatments that protect cells from deprivation of nerve growth factor failed to prevent the toxin-induced loss of neurites. Inactivation of SNAP-25 caused the accumulation at neurite branch sites of Golgi-derived organelles labelled with N-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-s-indacene-3-pentanoyl)-sphingosine conjugated to bovine serum albumin, prior to the collapse of arbors. Notably, neurite growth was ~1000-fold less susceptible to BoNT/A than cholinergic transmission in these neurons. Accordingly, a BoNT/A acceptor synaptic vesicle protein2 (SV2) was found to be colocalized with VAMP1-3, but not with VAMP7, which is implicated in the growth of neurites. In conclusion, neurites depend on SNAP-25 for extension but this is quite resistant to BoNT/A, possibly, because of a low density of SV2 at growth sites that are distant from the highly susceptible regions of neurotransmitter release.

Use of Botulinum Toxin Type A in the Management of Neonatal Brachial Plexus Palsy

To evaluate functional outcomes and the impact on surgical interventions after the use of botulinum neurotoxin type A (BoNT-A) for muscle imbalance, cocontractions, or contractures with neonatal brachial plexus palsy. A retrospective cohort study. A brachial plexus center in a tertiary children's hospital. Fifty-nine patients with neonatal brachial plexus palsy (75 injection procedures, 91 muscles and/or muscle groups) received BoNT-A injections (mean age at injection, 36.2 months; range, 6-123 months; 31 boys; 30 right-sided injuries, 28 left-sided injuries, 1 bilateral injury). Data collected retrospectively from medical records, from procedure notes andclinic visits before BoNT-A use, at≤6 months follow-up (BoNT-A active [BA]) andat≥7 months follow-up (BoNT-A not active [BNA]) included demographics, injection indication, side, and site(s), previous surgical history, occupational therapy and/or physical therapy plan, and outcome measurements. Outcomes assessed before and after injections included active and passive range of motion, Mallet and Toronto scores, parent comments about arm function, preinjection surgical considerations, and postinjection surgical history. Injection procedures included 51 to shoulder internal rotators, 15 triceps, 15 pronator teres, 9 biceps, and 1 flexor carpi ulnaris. Active and passive shoulder external rotation (SER) range of motion improved after shoulder internal rotator injections (P=.0003 and P= .002, respectively), as did Mallet scores with BA; the latter were sustained with BNA. Surgical intervention was averted, modified, or deferred after BoNT-A in 45% (n= 20) under surgical consideration before BoNT-A. Active elbow flexion improved in 67% (P= .005), sustained BNA (P= .004) after triceps injections; 2 of 7 patients averted surgery. Active supination improved with BA (P= .002), with gains sustained BNA (P=.016). Passive elbow extension improved after biceps injections by an average 17° (P= .004) BA, although not sustained BNA. BoNT-A is an effective adjunct to therapy and surgery in managing muscle imbalance, cocontractions, and contractures in neonatal brachial plexus palsy. Use of BoNT-A can result in averting, modifying, or deferring surgical interventions in a number of affected children.

Cost analysis of the use of botulinum toxin type A in Spain

To estimate treatment costs of blepharospasm, cervical dystonia(CD), upper limb spasticity (ULS) and spasticity in children with cerebral palsy (SCCP) with botulinum neurotoxin type A (BoNT-A) in Spain. Annual BoNT-A treatment costs were calculated (2013 ex-factory price () applying RDL 8/2010 and RDL 9/2011 deductions), based on initial dose (id), average dose (ad) and maximum dose (md) according to Summary of Product Characteristics of Botox® (100U/50U), Dysport®(500U) and Xeomin® (100U) and considering the use of complete vials.In addition, annual treatment costs were calculated considering the useof vials in more than one patient and also patient population annual treatment costs based on diseases' prevalence. Annual BoNT-A treatment costs per patient were estimated at between 265 and 2,120 with savings from 10% to 55% accordingto the selected BoNT-A. CD and ULS treatment provided the greatest cost per patient. Botox® provided greater savings in ULS (id/ad), CD(id), and in blepharospasm and SCCP (id/ad/md). Dysport® treatment was less costly in CD (md) and ULS (md), while Xeomin® was in CD(ad). Based on the estimated treated population in Spain, the annual treatment costs ranged from 368,392 to 13,958,836 depending on indication, dose and BoNT-A considered. The appropriate BoNT-A choice would lead to considerable savings for the National Health System. Botox® would generate lower costs per patient than other BoNT-A products in 9 out of 12 scenarios considered.

Botulinum neurotoxin A subtype 2 reduces pathological behaviors more effectively than subtype 1 in a rat Parkinson’s disease model

Recent reports indicate that interruption of acetylcholine release by intrastriatal injection of botulinum neurotoxin type A (BoNT/A) in a rat Parkinson’s disease model reduces pathogenic behavior without adverse side effects such as memory dysfunction. Current knowledge suggests that BoNT/A subtype 1 (BoNT/A1) and BoNT/A subtype 2 (BoNT/A2) exert different effects. In the present study, we compared the effects of BoNT/A1 and BoNT/A2 on rotation behavior and in vivo cleavage of presynaptic protein SNAP-25 in a rat unilateral 6-hydroxydopamine-induced Parkinson’s disease model. BoNT/A2 more effectively reduced pathogenic behavior by efficiently cleaving SNAP-25 in the striatum compared with that of BoNT/A1. Our results suggest that BoNT/A2 has greater clinical therapeutic value for treating subjects with Parkinson’s disease compared to that of BoNT/A1.

Selective inhibition of meningeal nociceptors by botulinum neurotoxin type A: Therapeutic implications for migraine and other pains

BackgroundMeningeal and other trigeminal nociceptors are thought to play important roles in the initiation of migraine headache. Currently, the only approved peripherally administered chronic migraine prophylactic drug is onabotulinumtoxinA. The purpose of this study was to determine how botulinum neurotoxin type A (BoNT-A) affects naïve and sensitized meningeal nociceptors.Material and methodsUsing electrophysiological techniques, we identified 43 C- and 36 Aδ-meningeal nociceptors, and measured their spontaneous and evoked firing before and after BoNT-A administration to intracranial dura and extracranial suture-receptive fields.ResultsAs a rule, BoNT-A inhibited C- but not Aδ-meningeal nociceptors. When applied to nonsensitized C-units, BoNT-A inhibited responses to mechanical stimulation of the dura with suprathreshold forces. When applied to sensitized units, BoNT-A reversed mechanical hypersensitivity. When applied before sensitization, BoNT-A prevented development of mechanical hypersensitivity. When applied extracranially to suture branches of intracranial meningeal nociceptors, BoNT-A inhibited the mechanical responsiveness of the suture branch but not dural axon. In contrast, BoNT-A did not inhibit C-unit responses to mechanical stimulation of the dura with threshold forces, or their spontaneous activity.DiscussionThe study provides evidence for the ability of BoNT-A to inhibit mechanical nociception in peripheral trigeminovascular neurons. These findings suggest that BoNT-A interferes with neuronal surface expression of high-threshold mechanosensitive ion channels linked preferentially to mechanical pain by preventing their fusion into the nerve terminal membrane.

The effect of botulinum neurotoxin type A on capsule formation around silicone implants: the in vivo and in vitro study

This study confirms that botulinum neurotoxin type A (BoNT-A) decreases capsular contracture and elucidates a possible mechanism. Silicone blocks were implanted subcutaneously in 20 mice. The experimental groups received BoNT-A (1, 2·5 or 5 U) instilled into the subcutaneous pocket. After 30 days, periprosthetic capsules were harvested and evaluated. The effect of BoNT-A on the differentiation of human dermal fibroblasts to myofibroblasts in culture was examined by Western blot analysis. Changes in transforming growth factor-beta1 (TGF-β1) expression in cultured fibroblasts were determined by enzyme-linked immunosorbent assay (ELISA). In in vivo study, the thickness of capsules (P < 0·05) and the number of alpha-smooth muscle actin (α-SMA)(+) cells in capsules (P < 0·05) were significantly decreased in the experimental groups. TGF-β1 was significantly underexpressed in the experimental groups (P < 0·05). In in vitro study, BoNT-A did not significantly affect fibroblast viability. Western blot analysis showed that α-SMA protein levels were significantly decreased in the experimental groups (P < 0·05). Based on ELISA, the amount of TGF-β1 was significantly decreased in the experimental groups (P < 0·05), especially cells treated with a high dose of BoNT-A (P < 0·001). This study confirms that BoNT-A prevents capsular formation around silicone implants, possibly by blocking TGF-β1 signalling and interrupting the differentiation of fibroblasts to myofibroblasts.

Time Course Analysis of the Effects of Botulinum Neurotoxin Type A on Pain and Vasomotor Responses Evoked by Glutamate Injection into Human Temporalis Muscles

The effect of botulinum neurotoxin type A (BoNTA) on glutamate-evoked temporalis muscle pain and vasomotor responses was investigated in healthy men and women over a 60 day time course. Subjects participated in a pre-BoNTA session where their responses to injection of glutamate (1 M, 0.2 mL) and saline (0.2 mL) into the temporalis muscles were assessed. On Day 1, BoNTA (5 U) was injected into one temporalis muscle and saline into the contralateral temporalis muscle, in a randomized order. Subjects then received intramuscular injections of glutamate (1 M, 0.2 mL) into the left and right temporalis muscles at 3 h and subsequently 7, 30 and 60 days post-injection of BoNTA. Pain intensity, pain area, and neurogenic inflammation (skin temperature and skin blood perfusion) were recorded. Prior to BoNTA treatment, glutamate evoked significantly greater pain and vasomotor reactions (P < 0.001) than saline. BoNTA significantly reduced glutamate-evoked pain intensity (P < 0.05), pain area (P < 0.01), skin blood perfusion (P < 0.05), and skin temperature (P < 0.001). The inhibitory effect of BoNTA was present at 3 h after injection, peaked after 7 days and returned to baseline by 60 days. Findings from the present study demonstrated a rapid action of BoNTA on glutamate-evoked pain and neurogenic inflammation, which is in line with animal studies.

보툴리눔 톡신 교근 주입 후 발생한 전방 개교합 증례보고

보툴리눔 톡신은 신경독소로, 운동신경 말단부위에서 분비되는 아세틸콜린의 분비를 차단하여 근육의 위축을 유발하게 된다. 의학계 및 치의학계에서는 이를 이용하여 다양한 질환을 치료하는 것을 시도하고 있다. 치과영역에서는 저작근 수축, 심한 이갈이, 안면 틱, 구강안면 운동장애, 교근비대의 치료 등 과활성 근육성 질환을 치료하는 데 사용하고 있다. 악안면 영역에 보툴리눔 톡신을 주입하고 난 뒤 발생되고 있는 합병증으로는, 자연스럽지 못한 안면표정, 통증의 증가, 두통 등이 유발될 수 있다고 보고되고 있다. 본 증례에서는 교근부에 보툴리눔 톡신 주입 후 발생된 전방 개교합 증상에 대하여 보고하고자 한다. Botulinum neurotoxin(BoNT) is a protease exotoxin produced from Clostridium botulinum. It works by blocking the release of acetylcholine from cholinergic nerve endings causing inactivity of muscles or glands. Recently, the therapeutic use of BoNT have expanded to include a wide range of medical and dental conditions. Botulinum neurotoxin type A(BoNT/A) is used off-label in the orofacial region to treat primary and secondary masticatory and facial muscle spasm, severe bruxism, facial tics, orofacial dyskinesias, dystonias, and hypertrophy of the masticatory muscles. Local hematoma, infection, and persistent pain in the injection site are the site-of-injection side effects. Medication-related side effects are adjacent muscle weakness, slurred speech, an alteration in the character of the saliva, and severe headaches. In most cases, these complications are not persistent and bothersome. We reported a case report of a patient who had transient anterior open bite after BoNT/A injection on masseter muscles to treat the refractory myofascial pain.

A quantitative bifunctional in vitro potency assay for botulinum neurotoxin serotype A

Introduction: Botulinum neurotoxin type A (BoNTA) is one of seven serotypes produced by Clostridium botulinum (types A thru G) and is the serotype most widely used to treat both cosmetic and medical conditions. Potency for botulinum toxin preparations is expressed in mouse LD50 units. There is a need to develop a non-animal based replacement for this potency assay. Methods: An in vitro potency assay measuring BoNTA activity has been developed that addresses both BoNTA heavy chain binding to its cell receptor SV2C and BoNTA light chain enzymatic activity in cleaving SNAP-25, an intracellular protein essential in neurotransmitter release. This bifunctional assay utilizes a 96 well microtiter format and well defined reagents. Assay characterization determined that the relative standard deviation for intermediate precision was less than 10%. Results: The assay standard curve covers the range of BoNTA concentrations from 0.0624 to 32ng/mL. Specificity was demonstrated with purified BoNTA heavy chain which inhibited the activity in a dose dependent manner. A correlation between this bifunctional assay and the mouse LD50 potency assay was demonstrated.

Very early reduction in efficacy of botulinum toxin therapy for cervical dystonia in patients with subsequent secondary treatment failure: a retrospective analysis

The objective of this study was to estimate the probability of development of partial secondary treatment failure (PSTF) in patients with cervical dystonia (CD) who had been treated over up to 9 years with repetitive intramuscular injections of botulinum neurotoxin type A (BoNT/A). The temporal course of treatment response in patients in whom PSTF was detected retrospectively was compared to patients with a normal clinical response. For this purpose, charts of all CD patients treated in our outpatient clinic between 1988 and 2001 were retrospectively analyzed. Extracted data included time of all injections, dose per visit, disease severity measured by TSUI scores, and time of determination of neutralizing antibodies. Final data analysis using a special formal definition of PSTF was based on charts of 568 patients having exclusively been treated with abobotulinumtoxinA. PSTF onset was observed in our CD cohort during the entire treatment period analyzed, with no clustering at any time point. Probability to develop PSTF was 14.5 % in 9 years. Thus, mean PSTF incidence was 1.6 % per year. The mean TSUI score of patients with retrospectively defined PSTF (n = 33) became already significantly worse after the second injection when compared with the group without PSTF (n = 535). Our data indicate that clinical response in patients developing PSTF later on differs from that of patients without PSTF already very early in the course of botulinum neurotoxin type A treatment, and that PSTF remains undetected at this early stage. Reduced response may therefore be present in a number of CD patients who think they still respond normally to continuous BoNT/A treatment.

Experience with botulinum toxin type A in the treatment of neurogenic detrusor overactivity in clinical practice

Control of the lower urinary tract is a complex, multilevel process that involves both the peripheral and central nervous system. Neurogenic lower urinary tract dysfunction (LUTD) is a widespread chronic illness that impairs millions of people worldwide. Neurogenic LUTD has a major impact on quality of life, affecting emotional, social, sexual, occupational and physical aspects of daily life, and in addition to the debilitating manifestations for patients, it also imposes a substantial economic burden on every healthcare system. First-line treatment for neurogenic LUTD includes antimuscarinics and some form of catheterization, preferably intermittent self-catheterization. However, the treatment effect is often unsatisfactory, so that other options have to be considered. Moreover, neurogenic LUTD is a challenge because all available treatment modalities (i.e. conservative, minimally invasive and invasive therapies) may fail. In recent years, botulinum neurotoxin type A (BoNT/A) treatment has been shown to be an effective pharmacological therapy option in patients refractory to antimuscarinic and neurogenic detrusor overactivity (NDO). Several studies have shown that BoNT/A injection significantly reduces detrusor muscle overactivity. Also BoNT/A treatment of NDO has revealed a significant improvement of lower urinary tract function with regard to reduced urinary incontinence, reduced detrusor pressure, increased bladder capacity and improved quality of life in NDO.

The effects of botulinum toxin injection frequency on calf muscle growth in young children with spastic cerebral palsy: A 12-month prospective study

This study was a 12-month prospective investigation of changes in the medial gastrocnemius (MG) muscle morphology in children aged 2-5years with spastic cerebral palsy (CP) who had received no previous intramuscular injections of botulinum neurotoxin type-A (BoNT-A) and were randomised to receive either single or multiple (three) BoNT-A injections to the gastrocsoleus. MG morphological changes were compared to age-matched typically developing (TD) peers. Thirteen children with spastic CP with a mean age of 45 (15) months and 18 TD children with a mean age of 48 (14) months participated in the study. The principal outcome measures were MG muscle volume, fascicle length, pennation angle and physiological cross-sectional area (PCSA), which were obtained using 2D and 3D ultrasound. The single and multiple injection frequency groups significantly increased MG muscle volume at 12months relative to the baseline by 13 and 15%, respectively. There were no significant differences in the MG muscle volume 28.5 (12.3) versus 30.3 (3.8)ml, fascicle length 48.0 (10.4) versus 44.8 (1.2)mm or PCSA 7.0 (1.2) versus 6.6 (1.7)cm(2) between the single and multiple injection groups, respectively, at 12months follow-up. The change in MG muscle volume in the single and multiple injection groups was significantly lower than the TD peers by 66 and 60%, respectively. In young children with spastic CP, naive to BoNT-A treatment, MG muscle growth over 12months does not appear to be influenced by intramuscular BoNT-A injection frequency. However, MG muscle growth in the spastic CP groups was significantly lower than the age-matched TD peers. It is unclear whether this is an effect of intramuscular BoNT-A injections or reduced growth rates in children with spastic CP in general. Controlled investigations and longitudinal studies with multiple measurement time points are required in order to determine the influence of BoNT-A treatment on muscle physiological and mechanical growth factors in young children with spastic CP.

Expression and purification of neurotoxin-associated protein HA-33/A from Clostridium botulinum and evaluation of its antigenicity.

Botulinum neurotoxin (BoNT) complexes consist of neurotoxin and neurotoxin-associated proteins. Hemagglutinin-33 (HA-33) is a member of BoNT type A (BoNT/A) complex. Considering the protective role of HA-33 in preservation of BoNT/A in gastrointestinal harsh conditions and also its adjuvant role, recombinant production of this protein is favorable. Thus in this study, HA-33 was expressed and purified, and subsequently its antigenicity in mice was studied. Initially, ha-33 gene sequence of Clostridium botulinum serotype A was adopted from GenBank. The gene sequence was optimized and synthesized in pET28a (+) vector. E. coli BL21 (DE3) strain was transformed by the recombinant vector and the expression of HA-33 was optimized at 37°C and 5 h induction time. The recombinant protein was purified by nickel nitrilotriacetic acid agarose affinity chromatography and confirmed by immunoblotting. Enzyme Linked Immunoassay showed a high titer antibody production in mice. The results indicated a highly expressed and purified recombinant protein, which is able to evoke high antibody titers in mice.

Transoral management of large calculi in submandibular gland with sialendoscopy

Objective: Botulinum neurotoxin type A (BoNT/A) shows effective in the treatment of sialorrhea. The purpose of this study was to investigate the long-term morphological and functional effects of BoNT/A on submandibular glands (SMGs) and elucidated its underline mechanisms. Methods: In rats treated with BoNT/A, we measured salivary flow rate of SMGs with modified Schirmer test and examined morphological changes through light and electron microscopic examinations at different time points (1, 2, 4, 12 and 24 weeks) after operation. Immunohistochemistry was used to evaluate acetylcholinesterase (AchE). Western blot were used to evaluate the protein levels of synaptosome-associated protein of 25 kDa (SNAP-25), M3 muscarinic acetylcholine receptor (M3R) and aquaporin 5 (AQP5). Immunofluorescence was used to assess the distribution of AQP5. Results: The salivary flow of the BoNT/A-treated glands decreased accompanied with glandular atrophy. The protein levels of SNAP-25 and AchE were downregulated while the protein levels of M3R were upregulated in treated glands. BoNT/A decreased the expression of AQP5 and inhibited translocations of AQP5 from the cytoplasm to the plasma membrane. These effects could be observed after 1 week, peaked at 2 weeks and recovered to normal level at 24 weeks. Conclusions: BoNT/A recoverably decreased salivary flow in a dose-dependent manner and led to temporary glandular atrophy. BoNT/A-induced inhibitory secretory mechanism involved not only temporary glandular denervation, but also the direct inhibition of AQP5 activity in SMGs.

ALGORITHM OF MUSCLES SELECTION FOR BOTULINUM TOXIN INJECTIONS AT PATIENTS WITH CEREBRAL PALSY

ALGORITHM OF MUSCLES SELECTION FOR BOTULINUM TOXIN INJECTIONS AT PATIENTS WITH CEREBRAL PALSY

Understanding the Functional Anatomy of the Frontalis and Glabellar Complex for Optimal Aesthetic Botulinum Toxin Type A Therapy

Botulinum neurotoxin type A (BoNTA) is approved for the treatment of glabellar lines and also is commonly injected in an off-label fashion in the frontalis (i.e., frontalis epicranius) muscle to improve the appearance of horizontal forehead lines. This study aimed to review and discuss both the anatomy and physiology of the frontalis muscle and its relationship with antagonist muscles in the upper face and to provide a guide for the use of BoNTA to treat forehead rhytides while minimizing the occurrence of complications such as brow ptosis. A PubMed search was conducted to identify practitioner opinion and clinical publications on the efficacy and safety of BoNTA for aesthetic treatment of the upper face. The use of BoNTA produces durable improvement in the appearance of moderate to severe horizontal forehead lines. Dose and injection technique must be adjusted and individualized based on the variable anatomy and function/mass of muscles in the forehead and upper face as well as on patient goals. Optimal aesthetic outcomes can be achieved by skillfully balancing the opposing effects of the frontalis muscle and its intricate interactions with the procerus, corrugator supercilii, depressor supercilii, and orbicularis oculi muscles. The use of BoNTA to improve the aesthetic appearance of horizontal forehead lines is optimized when clinicians take into account variations in frontalis muscle function and position, anatomy of the brow, and proper injection technique when they devise individualized treatment regimens.

Effects of early spasticity treatment on children with hemiplegic cerebral palsy: a preliminary study

To compare motor and functional performance of two groups of children with hemiplegic cerebral palsy (HCP). Only the study group (SG) received early treatment of spasticity with botulinum neurotoxin type A (BXT-A). Gross Motor Function Measure (GMFM), functional performance (Pediatric Evaluation of Disability Inventory - PEDI), range of movement, gait pattern (Physician Rating Scale - PRS) and the speed of hand movements were considered. The SG, composed of 11 HCP (45.64±6.3 months), was assessed in relation to the comparison group, composed of 13 HCP (45.92±6.4 months). SG showed higher scores in four of the five GMFM dimensions, which included scores that were statistically significant for dimension B, and higher scores in five of the six areas evaluated in the PEDI. Active wrist extension, the speed of hand movements and PRS score were higher in the SG. Children who received early BXT-A treatment for spasticity showed higher scores in motor and functional performance.

Stapling of the botulinum type A protease to growth factors and neuropeptides allows selective targeting of neuroendocrine cells

Precise cellular targeting of macromolecular cargos has important biotechnological and medical implications. Using a recently established ‘protein stapling’ method, we linked the proteolytic domain of botulinum neurotoxin type A (BoNT/A) to a selection of ligands to target neuroendocrine tumor cells. The botulinum proteolytic domain was chosen because of its well-known potency to block the release of neurotransmitters and hormones. Among nine tested stapled ligands, the epidermal growth factor was able to deliver the botulinum enzyme into pheochromocytoma PC12 and insulinoma Min6 cells; ciliary neurotrophic factor was effective on neuroblastoma SH-SY5Y and Neuro2A cells, whereas corticotropin-releasing hormone was active on pituitary AtT-20 cells and the two neuroblastoma cell lines. In neuronal cultures, the epidermal growth factor- and ciliary neurotrophic factor-directed botulinum enzyme targeted distinct subsets of neurons whereas the whole native neurotoxin targeted the cortical neurons indiscriminately. At nanomolar concentrations, the retargeted botulinum molecules were able to inhibit stimulated release of hormones from tested cell lines suggesting their application for treatments of neuroendocrine disorders.

Heat shock protein 70 overexpression attenuates botulinum neurotoxin type A induced skeletal muscle atrophy in rats

Heat shock protein 70 (Hsp70) is a ubiquitous, cytoprotective protein that is up‐regulated in response to cellular stress. Botulinum neurotoxin type A (BoNT/A) administration causes a chemical denervation which leads to skeletal muscle atrophy in rats. Previous work in skeletal muscle has shown that Hsp70 inhibits both NF‐κB and FOXO activation in response to certain stimuli. During periods of atrophy, Hsp70 levels are decreased, while NF‐κB and FOXO activity are increased and required for atrophy in some models. Therefore, the purpose of the current study was to determine if electrotransfer of Hsp70 into the soleus muscle of rats, prior to BoNT/A administration, is sufficient to inhibit atrophy and NF‐κB/FOXO activation. BoNT/A administration induced ~70% atrophy of the soleus. BoNT/A + Hsp70 administration elicited only ~50% atrophy. Hsp70 prevented the BoNT/A‐induced increase in total ubiquitin conjugated proteins. Furthermore, BoNT/A‐induced NF‐κB transactivation was abolished by Hsp70 and levels of FOXO3a‐phosphorylation were maintained. In conclusion, while Hsp70 decreases total ubiquitin conjugated proteins and attenuates a portion of the observed skeletal muscle atrophy, these data suggest that pathways other than NF‐κB/FOXO may predominate in control of protein degradation. Supported by Ipsen Pharmaceuticals.

Botulinum Neurotoxin Type A is Internalized and Translocated from Small Synaptic Vesicles at the Neuromuscular Junction

Botulinum neurotoxin type A (BoNT/A) is the most frequent cause of human botulism and, at the same time, is largely used in human therapy. Some evidence indicates that it enters inside nerve terminals via endocytosis of synaptic vesicles, though this has not been directly proven. The metalloprotease L chain of the neurotoxin then reaches the cytosol in a process driven by low pH, but the acidic compartment wherefrom it translocates has not been identified. Using immunoelectron microscope, we show that BoNT/A does indeed enter inside synaptic vesicles and that each vesicle contains either one or two toxin molecules. This finding indicates that it is the BoNT/A protein receptor synaptic vesicle protein 2, and not its polysialoganglioside receptor that determines the number of toxin molecules taken up by a single vesicle. In addition, by rapid quenching the vesicle trans-membrane pH gradient, we show that the neurotoxin translocation into the cytosol is a fast process. Taken together, these results strongly indicate that translocation of BoNT/A takes place from synaptic vesicles, and not from endosomal compartments, and that the translocation machinery is operated by no more than two neurotoxin molecules.