title: Botulinum toxin B increases intrinsic muscle activity in organotypic spinal cord-skeletal muscle co-cultures.
abstract: In organotypic spinal cord-skeletal muscle co-cultures, motoneurons are driven by locomotor commands and induce contractions in surrounding muscle fibres. Using these co-cultures, it has been shown that effects of organophosphorus compounds on neuromuscular synapses can be determined in vitro. In the present study we aimed to extend this in vitro tool for pharmacologic testing of botulinum toxin B. This neurotoxin is widely used for the treatment of dystonia. Besides its effects on the neuromuscular junction, botulinum toxins may also act at centrally located synapses. Incubation with botulinum toxin B (Neurobloc(®)) induced a significant increase in muscular activity after 24, 48 and 72h. Application of the NMDA- and AMPA-receptor antagonists AP5 (20μM) and CNQX (15μM) induced a similar augmentation of muscle activity after 48 and 72h, respectively. Administration of the glycine- and GABA(A)-receptor antagonists strychnine (1μM) and bicuculline (100μM) did not alter intrinsic muscle activity. In contrast, application of a non-depolarizing muscle relaxant rocuronium bromide reduced the muscle activity in a dose-dependent manner. Our findings suggest that glutamatergic synapses in the spinal cord are more sensitive to botulinum toxin B than synaptic contacts between spinal motoneurons and muscle fibres.
authors.affiliation: Experimental Anesthesiology Section, Department of Anesthesiology and Intensive Care Medicine, Eberhard-Karls-University, Tübingen, Germany. Electronic address: veit-simon.eckle@uni-tuebingen.de.
authors.forename: Veit-Simon
authors.initials: VS
authors.lastname: Eckle
authors.affiliation: Experimental Anesthesiology Section, Department of Anesthesiology and Intensive Care Medicine, Eberhard-Karls-University, Tübingen, Germany.
authors.forename: Monika
authors.initials: M
authors.lastname: Balk
authors.affiliation: Bundeswehr Institute of Pharmacology and Toxicology, Munich, Germany.
authors.forename: Horst
authors.initials: H
authors.lastname: Thiermann
authors.affiliation: Experimental Anesthesiology Section, Department of Anesthesiology and Intensive Care Medicine, Eberhard-Karls-University, Tübingen, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Antkowiak
authors.affiliation: Experimental Anesthesiology Section, Department of Anesthesiology and Intensive Care Medicine, Eberhard-Karls-University, Tübingen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Grasshoff
mesh_terms: D065087:Acetylcholine Release Inhibitors / Q000494:pharmacology*; D000818:Animals; D019274:Botulinum Toxins, Type A / Q000494:pharmacology*; D018920:Coculture Techniques; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018715:Microscopy, Video; D009046:Motor Neurons / Q000187:drug effects* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000294:innervation / Q000378:metabolism; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000378:metabolism; D018091:Receptors, AMPA / Q000187:drug effects / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000378:metabolism; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects; D013997:Time Factors; D046509:Tissue Culture Techniques
chemical_list: D065087:Acetylcholine Release Inhibitors; D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; C096323:rimabotulinumtoxinB; D018698:Glutamic Acid; D019274:Botulinum Toxins, Type A
keywords: Botulinum toxin B; Glutamatergic neurotransmission; In vitro testing; Motoneuron; Muscle activity; Organotypic spinal cord cultures