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.

Ex vivogut culture for studying differentiation and migration of small intestinal epithelial cells

“…However, no ICC was detected, and peristalsis was even enhanced by neurotoxin in ex vivo guts, indicating that peristalsis in ex vivo gut is not due to ICC functionality. Likewise, botulinum toxin could even increase muscular activity in a spinal cord–muscle coculture system [ 44 ]. In short, our cultured ex vivo gut has mesenchymal layers which can be useful for studying epithelial motility.…”

Spontaneous and Evoked Activity from Murine Ventral Horn Cultures on Microelectrode Arrays

“…Therefore, there has been considerable interest in developing neuromuscular junction models in vitro . Several models have relied on open architecture, common-culture of MNs and skeletal myocytes ( Das et al, 2007 ; Drexler et al, 2011 ; Eckle et al, 2016 ), while more recent studies have demonstrated the feasibility of compartmentalized MN/myotube co-cultures ( Zahavi et al, 2015 ; Uzel et al, 2016 ). These preparations exhibit immunohistochemical markers as well as electrophysiological and/or contractile events characteristic of functional neuromuscular transmission.…”

In Vitro Innervation as an Experimental Model to Study the Expression and Functions of Acetylcholinesterase and Agrin in Human Skeletal Muscle

“…For instance, in a homologous mouse-mouse model, which uses explants of embryonic mouse spinal cord and skeletal muscle, contractions of skeletal muscle cells are completely suppressed by succinylcholine (aka suxamethonium) [ 99 , 100 ], a depolarizing nAChR agonist and an NMJ blocker. Contractions in this model are also suppressed by nAChR antagonist rocuronium [ 119 ], as well as by AChE inhibitors, such as soman and VX [ 100 , 120 ], and by botulinum toxin [ 98 ], which blocks release of ACh from presynaptic terminals. Furthermore, in a homologous rat-rat model, in which both spinal cord and skeletal muscle cells are obtained from rat embryos, the pattern of contractions is modulated by application of strychnine and bicuculline, which antagonize effects of inhibitory neurotransmitters glycine and GABA, respectively, as well as by electrical stimulation of spinal cord explants [ 68 ], which underscores the role of motor neurons in driving the muscle activity.…”