Elevation in type I interferons inhibits HCN1 and slows cortical neuronal oscillations.

Central nervous system (CNS) inflammation involves the generation of inducible cytokines such as interferons (IFNs) and alterations in brain activity, yet the interplay of both is not well understood. Here, we show that in vivo elevation of IFNs by viral brain infection reduced hyperpolarization-activated currents (Ih) in cortical pyramidal neurons. In rodent brain slices directly exposed to type I IFNs, the hyperpolarization-activated cyclic nucleotide (HCN)-gated channel subunit HCN1 was specifically affected. The effect required an intact type I receptor (IFNAR) signaling cascade. Consistent with Ih inhibition, IFNs hyperpolarized the resting membrane potential, shifted the resonance frequency, and increased the membrane impedance. In vivo application of IFN-ß to the rat and to the mouse cerebral cortex reduced the power of higher frequencies in the cortical electroencephalographic activity only in the presence of HCN1. In summary, these findings identify HCN1 channels as a novel neural target for type I IFNs providing the possibility to tune neural responses during the complex event of a CNS inflammation.

Behavioral and structural effects of unilateral intrastriatal injections of botulinum neurotoxin a in the rat model of Parkinson's disease.

Botulinum neurotoxin (BoNT) inhibits the release of acetylcholine from presynaptic vesicles through its proteinase activity cleaving the SNARE complex. Parkinson's disease (PD) is associated with locally increased cholinergic activity in the striatum. Therefore, the present study investigates the effect of unilateral intrastriatal BoNT-A injection in naïve rats on striatal morphology; i.e., the total number of Nissl-stained neurons and the volume of caudate-putamen (CPu) were estimated. Furthermore, stainings for markers of gliosis (glial fibrillary acidic protein) and microglia (Iba1) were performed. In addition, the potential beneficial effects of a unilateral intrastriatal injection of BoNT-A on motor activity in the rat model of hemi-PD were evaluated. Hemi-PD was induced by unilateral injection of 6-hydroxydopamine (6-OHDA) into the right medial forebrain bundle. Six weeks later, rats received an ipsilateral intrastriatal injection of BoNT-A. Behaviorally, motor performance was tested. The total number of CPu neurons and the striatal volume were not significantly different between the BoNT-A-injected right and the intact left hemispheres of naïve rats. In hemi-PD rats, intrastriatal BoNT-A abolished apomorphine-induced rotations, increased amphetamine-induced rotations, and tended to improve left forelimb usage. Forced motor function in the accelerod test was not significantly changed by BoNT-A, and open field activity was also unaltered compared with sham treatment. Thus, intrastriatal BoNT-A affects spontaneous motor activity of hemi-PD rats to a minor degree compared with drug-induced motor function. In the future, tests assessing the cognitive and emotional performance should be performed to ascertain finally the potential therapeutic usefulness of intrastriatal BoNT-A for PD.

Elevated levels of S100B, tau and pNFH in cerebrospinal fluid are correlated with subtypes of Guillain-Barré syndrome.

Guillain-Barré syndrome (GBS) is an immune-mediated inflammatory disease in the peripheral nervous system. Specific biomarkers for the two most common clinical subtypes of GBS, i.e., acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN) are still missing. The distinctive pathological features of AIDP and AMAN may lead to release of such specific biomarkers including glial markers (calcium-binding astroglial protein, S100B) and axonal damage markers [axoskeletal protein, phosphorylated neurofilament heavy protein (pNFH); cytoskeletal protein, tau], etc. To explore the potentials of biochemical markers for differential diagnosis and evaluation of prognosis of clinical subtypes in GBS, we used ELISA to measure the levels of S100B, tau and pNFH in serum and cerebrospinal fluid (CSF) from the patients with AIDP, AMAN, viral encephalitis and other non-inflammatory neurological disorders (OND), respectively. The values of albumin quotient and IgG index in CSF are significantly higher in AIDP and AMAN than in OND. The levels of S100B, tau and pNFH in serum and CSF are elevated in the patients with AIDP and AMAN compared to OND. The concentrations of these proteins are all higher in CSF than in serum. Increased levels of S100B in CSF at the acute phase are positively correlated with the GBS disability scale scores (GDSs) in AIDP, whereas enhanced levels of tau and pNFH in CSF are positively correlated with the GDSs in AMAN. Increased CSF levels of S100B, tau and pNFH at the acute phase may predict a poor prognosis and evaluate the severity of AIDP or AMAN at plateau and the recovery phase. Elevated levels of pNFH in CSF may be used for differentiating between AMAN and AIDP.

Intrastriatal botulinum toxin abolishes pathologic rotational behaviour and induces axonal varicosities in the 6-OHDA rat model of Parkinson's disease.

Central pathophysiological pathways of basal ganglia dysfunction imply a disturbed interaction of dopaminergic and cholinergic circuits. In Parkinson's disease (PD) imbalanced cholinergic hyperactivity prevails in the striatum. Interruption of acetylcholine (ACh) release in the striatum by locally injected botulinum neurotoxin A (BoNT-A) has been studied in the rat 6-hydroxydopamine (6-OHDA) model of PD (hemi-PD). The hemi-PD was induced by injection of 6-OHDA into the right medial forebrain bundle. Motor dysfunction provoked by apomorphine-induced contralateral rotation was completely reversed for more than 3 months by ipsilateral intrastriatal application of 1-2 ng BoNT-A. Interestingly, BoNT-A injected alone into the right striatum of naïve rats caused a slight transient ipsilateral apomorphine-induced rotation, which lasted only for about one month. Immunohistochemically, large axonal swellings appeared within the striatum injected with BoNT-A, which we tentatively named BoNT-A-induced varicosities. They contained either choline acetyltransferase or tyrosine hydroxylase. These findings suggest a selective inhibition of evoked release of ACh by locally applied BoNT-A. Intrastriatal application of BoNT-A may antagonize localized relative functional disinhibited hypercholinergic activity in neurodegenerative diseases such as PD avoiding side effects of systemic anti-cholinergic treatment.

Differential susceptibility to experimental autoimmune neuritis in Lewis rat strains is associated with T-cell immunity to myelin antigens.

Experimental autoimmune neuritis (EAN) is a CD4(+) T-cell-mediated inflammatory demyelinating disease of the peripheral nervous system (PNS) that serves as a model for Guillain-Barré syndrome (GBS) in humans. Various rat strains show different susceptibility to EAN. We examined PNS myelin-induced T- and B-cell responses and cytokine production in order to explore the mechanisms behind different EAN susceptibility in the three Lewis rat strains, Hannover, Charles River, and Taconic. Lewis rats of Hannover and Charles River strains exhibited a higher susceptibility to EAN than Lewis rats of the Taconic strain. The higher susceptibility was associated with increased inflammatory cell infiltrates and major histocompatibility class II expression as well as enhanced mitogenic (phytohemagglutinin-induced) and antigen-specific (P2 peptide 57-81-induced) lymphocyte proliferation compared with the Taconic strain. The Hannover strain also showed increased proinflammatory cytokine (interferon-γ and tumor necrosis factor-α) production in the PNS. Cross-cultures of T cells and macrophages from Hannover and Taconic rats revealed that the Hannover rats exerted the strongest priming function of T cells. In contract, the P2 peptide-induced antibody production was not different among the three Lewis rat strains. In conclusion, the differential susceptibility to EAN of Lewis rat strains is correlated primarily with T-cell immunity to myelin antigens.

Kainic acid-induced microglial activation is attenuated in aged interleukin-18 deficient mice.

BACKGROUND: Previously, we found that interleukin (IL)-18 deficiency aggravates kainic acid (KA)-induced hippocampal neurodegeneration in young C57BL/6 mice due to an over-compensation by IL-12. Additionally, IL-18 participates in fundamental inflammatory processes that increase during aging. In the present study, we were interested in the role of IL-18 in KA-induced neurodegeneration in aged female C57BL/6 mice. METHODS: Fifteen aged female IL-18 knockout (KO) and 15 age-matched wild-type (WT) mice (18 to 19 months old) were treated with KA at a dose of 25 mg/kg body weight intranasally. Seizure activities and behavioral changes were rated using a 6-point scoring system and open-field test, respectively. Seven days after KA treatment, degenerating neurons were detected by Nissl's method and Fluoro-Jade B staining; and microglial activation was analyzed by immunohistochemistry and flow cytometry. RESULTS: Aged female IL-18 KO and WT mice showed similar responses to treatment with KA as demonstrated by comparable seizure activities, behavioral changes and neuronal cell death. However, aged female IL-18 KO mice failed to exhibit the strong microglial activation shown in WT mice. Interestingly, even though the number of activated microglia was less in KA-treated IL-18 KO mice than in KA-treated WT mice, the proportion of microglia that expressed the cytokines tumor necrosis factor (TNF)-alpha, IL-6 and IL-10 was higher in KA-treated IL-18 KO mice. CONCLUSION: Deficiency of IL-18 attenuates microglial activation after KA-induced excitotoxicity in aged brain, while the net effects of IL-18 deficiency are balanced by the enhancement of other cytokines, such as TNF-alpha, IL-6 and IL-10.

Frequency and risk factors of antibody-induced secondary failure of botulinum neurotoxin therapy.

OBJECTIVE: To investigate the risk factors of neutralizing antibody (NAB)-induced complete secondary treatment failure (cSTF) during long-term botulinum neurotoxin (BoNT) treatment in various neurologic indications. METHODS: This monocenter retrospective cohort study analyzed the data of 471 patients started on BoNT therapy between 1995 and 2015. Blood samples of 173 patients were investigated for NABs using the mouse hemidiaphragm test (93 with suspected therapy failure, 80 prospective study participants). The frequency of NAB-cSTF was assessed for various indications: hemifacial spasm, blepharospasm, cervical dystonia, other dystonia, and spasticity. A priori defined potential risk factors for NAB-cSTF were evaluated, and a stepwise binary logistic regression analysis was performed to identify independent risk factors. RESULTS: Treatment duration was 9.8 ± 6.2 years (range, 0.5-30 years; adherence, 70.6%) and number of treatment cycles 31.2 ± 22.5 (3-112). Twenty-eight of 471 patients (5.9%) had NAB-cSTF at earliest after 3 and at latest after 103 treatment cycles. None of the 49 patients treated exclusively with incobotulinumtoxinA over 8.4 ± 4.2 (1-14) years developed NAB-cSTF. Independent risk factors for NAB-cSTF were high BoNT dose per treatment, switching between onabotulinumtoxinA and other BoNT formulations (except for switching to incobotulinumtoxinA), and treatment of neck muscles. CONCLUSIONS: We present a follow-up study with the longest duration to date on the incidence of NAB-cSTF in patients treated with various BoNT formulations, including incobotulinumtoxinA. Whereas the overall risk of NAB-cSTF is low across indications and BoNT formulations, our findings underpin the recommendations to use the lowest possible dose particularly in cervical dystonia, and to avoid unnecessary switching between different formulations.

Prevalence of neutralising antibodies in patients treated with botulinum toxin type A for spasticity.

Botulinum toxin (BT) has been used with great success to treat various muscle hyperactivity disorders. Occasionally, antibodies against BT (BT-AB) can be formed. When they are directed against the neurotoxin component of the BT drug, they are called neutralising antibodies. They can reduce the therapeutic effect partially or completely. We have measured neutralising BT-AB by use of the mouse diaphragm assay (MDA) in 42 adult patients with spasticity in the order of their appearance in the clinic. The patients had been treated for at least 2 years with BT type A (BT-A) and received on an average 14.2 +/- 6.1 BT-A injection series. BT-A was applied as Botox only, Dysport only or by sequential application of both preparations. The mean cumulative doses were 4,610 +/- 1,936 units Botox and 14,033 +/- 7,566 units Dysport, respectively. The mean treatment time was 4.5 +/- 1.8 (2-8) years. All patients were initially responsive to BT-A therapy. MDA detected BT-AB in 12% (5/42) of patients. However, in three patients the BT-AB titre was very low (<0.3 mIU/ml), in one it was intermediate (0.6 mIU/ml) and in one patient it was high (>1.0 mIU/ml). All BT-AB negative patients and also two of the patients with low BT-AB titre remained clinically responsive to BT therapy throughout the study. In conclusion, prevalence of BT-AB formation with clinical relevance (6%, 3/42) in adult patients with spasticity is not higher than that of BT-treated patients with cervical dystonia and much lower than that of BT-treated patients with infantile cerebral palsy.

TNF-alpha receptor 1 deficiency enhances kainic acid-induced hippocampal injury in mice.

The exact role of TNF-alpha in excitotoxic neurodegeneration of the brain is unclear. To address this issue, the kainic acid (KA)-induced hippocampal injury model, a well-characterized model of human neurodegenerative diseases, was used in TNF-alpha receptor 1 (TNFR1)-knockout (TNFR1-/-) mice in the present study. After nasal application of a single dose of 40 mg of KA per kilogram body weight, TNFR1-/- mice showed significantly more severe seizures than the wild-type mice. In addition, obvious neurodegeneration, enhanced microglia activation, and astrogliosis in the hippocampus, as well as increased locomotor activity, were found in TNFR1-/- mice compared with the wild-type controls 8 days after KA delivery. Moreover, CC chemokine receptor 3 expression on activated microglia was increased 3 days after KA treatment in TNFR1-/- mice, as measured by flow cytometry. These data suggest that TNF-alpha may play a protective role through TNFR1 signaling.

Animal models of multiple sclerosis for the development and validation of novel therapies - potential and limitations.

Various types of experimental autoimmune encephalomyelitis (EAE) reflect some of the pathogenetic, clinical, and therapeutic features of the different forms of multiple sclerosis (MS), thereby, providing some, albeit limited, insight into the molecular and cellular basis of the human disease. Specific questions of MS therapy including the search for new therapeutic targets and strategies and their validation require investigations in different available EAE models. A survey is given of experimental therapeutic approaches that are currently under study with the most promising examples of monoclonal antibodies, gene therapy, stem cell transplantation and orally applied small molecular weight disease-modifying drugs. Reasons for therapy failure and adverse side-effects of some experimental trials are discussed. Precaution is advised, if results of new experimental approaches are translated into clinical practice.

alpha4-Integrin antagonism with natalizumab: effects and adverse effects.

Based on the results of two phase III clinical trials, the humanized recombinant monoclonal antibody natalizumab was approved for the treatment of relapsing forms of multiple sclerosis (MS). Since its initial approval in November 2004, it has been announced that six patients who received natalizumab in the context of clinical studies acquired an infection with the human polyoma virus JC and were diagnosed with progressive multifocal leukoencephalopathy (PML). Two of these individuals had a fatal outcome. Our groups recently showed that natalizumab therapy results in a reduction of CD4(+) T cells within the cerebrospinal fluid (CSF) that is ten-fold more pronounced than the reduction in the number of CD8(+) T lymphocytes. Interestingly, it appears that the effect of natalizumab on cell numbers in the CSF persists for at least 6 months after cessation of treatment. More recently, we studied the expression of major histocompatibility complex (MHC) I and II, and the number and phenotypes of leukocytes in cerebral perivascular spaces (CPVS). We observed that natalizumab therapy was associated with a significant decrease in the cell surface expression of MHC class II molecules, and the numbers of dendritic cells in CPVS. In addition, no CD4(+) T cells were detectable in this compartment. Our observations may explain the differential and prolonged effects of natalizumab therapy on different leukocyte subsets in the central nervous system. They also suggest that natalizumab treatment may result in prolonged immunosuppression in peripheral organs, and the delayed onset of adverse events.

Arterial ischemic stroke: experience in Chinese children.

The aim of this study was to review cases of pediatric arterial ischemic stroke among Chinese subjects and thereby evaluate risk factors, clinical and neuroimaging features, and treatment, to establish a reasonable guideline for assessment and management of the disease. Between 1996 and 2006, 157 children (male:female ratio, 1.4:1) with arterial ischemic stroke were identified at Beijing Children's Hospital. The median age at stroke was 32 months (range, 4-192). Among patients with determined etiology, infections (12.1%), moyamoya disease (12.1%), and trauma (10.8%) were the most common. In 51 patients, there were no obvious risk factors (32.5%). Hemiplegia was the most common presenting feature (81.5%). The region of left middle cerebral artery was most frequently affected (36.3%), followed by the right middle cerebral artery (29.9%). Of the 157 patients, 56 were treated by intravenous thrombolytic agents (35.7%), all but one of them successfully (the one exception involving hemorrhagic complication). Randomized controlled trials are needed to establish primary prevention, acute treatment, and secondary prevention of pediatric ischemic stroke.

IL-18 deficiency inhibits both Th1 and Th2 cytokine production but not the clinical symptoms in experimental autoimmune neuritis.

IL-18 deficient (IL-18-/-) mice were used to investigate the role of IL-18 in the pathogenesis of experimental autoimmune neuritis (EAN) which was induced by immunization of the mice with P0 protein peptide 180-199. The clinical course was not different between IL-18-/- and wild-type mice. The splenic mononuclear cell (MNC) proliferation was also similar in both animal groups. However, the percentages of IFN-gamma, IL-10 and IL-12 positive cells were decreased among infiltrating MNC of cauda equine in IL-18-/- mice. This indicates that IL-18 deficiency inhibits the production of both Th1 and Th2 cytokines in the target organ of mice with EAN.

Aggravation of experimental autoimmune neuritis in TNF-alpha receptor 1 deficient mice.

The role of tumor necrosis factor (TNF)-alpha and its receptors in the pathogenesis of experimental autoimmune neuritis (EAN) induced by P0 peptide 180-199 in TNFR1 (p55) deficient (TNFR1-/-) mice was investigated. Compared to wild type EAN mice, TNFR1-/- EAN mice developed significantly more severe clinical signs, in parallel with enhanced numbers of inflammatory infiltrating cells in peripheral nerves and splenic P0-reactive T cell proliferation, as well as increased obviously MHC class II and CCR3 expression on the macrophages in the cauda equina. Our data indicated that TNF-alpha might have anti-inflammatory effect preventing the development of EAN in this mouse model.

Immunology and neurology.

The classical field of neuroimmunology deals with the immune response in infectious, autoimmune-mediated, ischemic, degenerative, traumatic, and neoplastic diseases of the nervous system with a major focus on immune-mediated demyelination. Recently more and more evidence points to a broader interaction between the immune and nervous systems via morphological connections, shared signal molecules and common mechanisms of signal transduction. Consequently, immune processes affect nervous functions and vice versa under both physiologic and pathologic conditions. This includes neuroendocrine (hormonal) and vegetative (neurotransmitter-mediated) influences on the immune response including conditioned immunostimulation and immunosuppression (neuroimmunomodulation) as well as effects of immune mediators (cytokines) on neuronal and psychic functions (psychoneuroimmunology). These findings have a strong impact on future strategies for the treatment of somatic as well as psychiatric diseases.

Prevalence of Fabry disease in patients with cryptogenic stroke: a prospective study.

BACKGROUND: Strokes are an important cause of morbidity and mortality in young adults. However, in most cases the cause of the stroke remains unclear. Anderson-Fabry disease is an X-linked recessive lysosomal storage disease resulting from deficient alpha-galactosidase and causes an endothelial vasculopathy followed by cerebral ischaemia. To determine the importance of Fabry disease in young people with stroke, we measured the frequency of unrecognised Fabry disease in a cohort of acute stroke patients. METHODS: Between February, 2001, and December, 2004, 721 German adults aged 18 to 55 years suffering from acute cryptogenic stroke were screened for Fabry disease. The plasma alpha-galactosidase activity in men was measured followed by sequencing of the entire alpha-GAL gene in those with low enzyme activity. By contrast, the entire alpha-GAL gene was genetically screened for mutations in women even if enzyme activity was normal. FINDINGS: 21 of 432 (4.9%) male stroke patients and seven of 289 (2.4%) women had a biologically significant mutation within the alpha-GAL gene. The mean age at onset of symptomatic cerebrovascular disease was 38.4 years (SD 13.0) in the male stroke patients and 40.3 years (13.1) in the female group. The higher frequency of infarctions in the vertebrobasilar area correlated with more pronounced changes in the vertebrobasilar vessels like dolichoectatic pathology (42.9%vs 6.8%). INTERPRETATION: We have shown a high frequency of Fabry disease in a cohort of patients with cryptogenic stroke, which corresponds to about 1.2% in young stroke patients. Fabry disease must be considered in all cases of unexplained stroke in young patients, especially in those with the combination of infarction in the vertebrobasilar artery system and proteinuria.

Maternal IgG suppresses NMDA-induced spasms in infant rats and inhibits NMDA-mediated neurotoxicity in hippocampal neurons.

Maternal immunoglobulin G (IgG) was derived from Wistar rats that just delivered the new offsprings. We examined the effect of this maternal IgG on infantile spasms induced by N-methyl-d-aspartate (NMDA) in immature rats. Pup animals were treated subcutaneously with 10 mg/kg/day maternal IgG from day 11 to day 15 after birth followed by a single intraperitoneal dose of NMDA (15 mg/kg). Administration of maternal IgG decreased the severity and increased the number of ACTH immunoreactive cells in the cortex of rats with NMDA-induced spasms. Furthermore, maternal IgG inhibited NMDA-induced intracellular LDH activity in cultured hippocampal neurons in a dose-dependent manner. The results indicate that maternal IgG can attenuate NMDA-induced seizures. In infantile spasms, some factors may during pregnancy negatively affect the transfer of maternal IgG from mother to fetus thereby causing a decrease in the amount of protective maternal IgG.

Immunoglobulins--basic considerations.

Immunoglobulins (Igs) or antibodies (Abs) are the principal operators of the adaptive humoral immune response. For optimum functional activity they acquire an optimized structure for antigen (Ag) recognition, precipitation, agglutination, phagocytosis (IgG1/3 and IgA), cytotoxicity (IgG1/3), transport through mucosa (IgA and IgM) and placenta (IgG1/3), complement activation (IgG1/3 and IgM) and release of inflammatory mediators (IgE). A diversity with potentially up to 10(15) different Ab specificities is generated during Ag-independent B cell development in the bone marrow by combinatorial V-D-J joining, creation of junctional diversity, and combinatorial association of L and H chains. Furthermore,Ab variety is created during Ag-dependent B cell maturation in peripheral lymphatic tissues by isotype class switching and somatic hypermutation. Two types of enzymes play a key role in Ab diverseness, i. e., the products of recombination-activating genes RAG1 and RAG2 and the affinity induced deaminase (AID). The prevailing adult-type B2 cells provide the basis for the acquired humoral immune response characterized by Ab production,Ag processing and presentation, immunological memory and tolerance along with the generation of the anti-idiotype network,whereas the fetal-type B1 cells may play a role in innate immunity and autoimmunity. Impairment of B cell immunity includes immunodeficiency (agammaglobulinemia), malignant transformation (leukemia, lymphoma, plasmocytoma) and immune dysregulation (allergy, autoimmunity). The diagnostic relevance of Abs comprises classical serology (immunoprecipitation, agglutination, complement binding, RIA, ELISA), immunocytochemistry and immunohistochemistry, immunofluorescence (microscopic and flow cytometric), cytotoxicity tests, immunoblots, immunospot assays and immunoabsorption (affinity chromatography). Therapeutic application of Abs (passive immunization) is directed against infections, intoxications, solid tumors, leukemias and lymphomas, graft rejection and graft-versus-host reaction, hemolytic anemia, and autoimmune diseases. The generation of genetically engineered monoclonal Abs (mAbs) has revolutionized the diagnostic and therapeutic potential of Abs in almost all disciplines of modern medicine.

Prospective study of first-choice topiramate therapy in newly diagnosed infantile spasms.

OBJECTIVE: This was a prospective open study to establish the efficacy, tolerability, and problems associated with the use of topiramate as first-choice drug in children with infantile spasms. METHODS: Open-label follow-up study, ranging from 24 to 36 months, of the cases of 54 patients with infantile spasms treated initially with topiramate as first-choice drug. RESULTS: Thirty-one patients (57.4%) were seizure free for more than 24 months; 9 patients were treated with topiramate alone and 22 patients with topiramate plus nitrazepam and/or valproate. In 44 cases (81.4%), the reduction of seizure frequency from baseline was greater than 30%, whereas in 10 cases (18.6%), there was poor or no response. The average dosage applied was 5.2 mg/kg per day (maximum dosage, 26 mg/kg per day; minimum dosage, 1.56 mg/kg per day). Adverse events occurred in 14 patients (26%). They included poor appetite leading to anorexia, absence of sweating, and sleeplessness. CONCLUSIONS: Topiramate proves to be an effective and safe first-choice drug not only as adjunctive but also as monotherapy of infantile spasms in children younger than 2 years.

Intrastriatal injection of botulinum neurotoxin-A is not cytotoxic in rat brain - A histological and stereological analysis.

Parkinson's disease (PD) is caused by progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta, resulting in a deficiency of dopamine in the striatum and an increased release of acetylcholine by tonically active interneurons. Botulinum neurotoxin-A (BoNT-A) is well known for blocking transmitter release by cholinergic presynaptic terminals. Treating striatal hypercholinism by local application of BoNT-A could be a possible new local therapy option of PD. In previous studies of our group, we analyzed the effect of BoNT-A injection into the CPu of 6-OHDA lesioned hemiparkinsonian rats. Our studies showed that BoNT-A application in hemiparkinson rat model is capable of abolishing apomorphine induced rotations for approximately 3 months. Regularly occurring axonal swellings in the BoNT-A infiltrated striata were also discovered, which we named BoNT-A induced varicosities (BiVs). Résumé: Here we investigated the long-term effect of the injection of 1ng BoNT-A into the right CPu of naive Wistar rats on the number of ChAT-ir interneurons as well as on the numeric density and the volumetric size of the BiVs in the CPu. Significant differences in the number of ChAT-ir neurons between the right BoNT-A treated CPu and the left untreated CPu were not detected up to 12 month post BoNT-A injection. The numeric density of BiVs in the treated CPu reached a maximum 3 months after BoNT-A treatment and decreased afterwards, whereas the volume of single BiVs increased steadily throughout the whole time course of the experiment.