title: Botulinum neurotoxin type A modulates vesicular release of glutamate from satellite glial cells.
abstract: This study investigated the presence of cell membrane docking proteins synaptosomal-associated protein, 25 and 23 kD (SNAP-25 and SNAP-23) in satellite glial cells (SGCs) of rat trigeminal ganglion; whether cultured SGCs would release glutamate in a time- and calcium-dependent manner following calcium-ionophore ionomycin stimulation; and if botulinum neurotoxin type A (BoNTA), in a dose-dependent manner, could block or decrease vesicular release of glutamate. SGCs were isolated from the trigeminal ganglia (TG) of adult Wistar rats and cultured for 7 days. The presence of SNAPs in TG sections and isolated SGCs were investigated using immunohistochemistry and immunocytochemistry, respectively. SGCs were stimulated with ionomycin (5 μM for 4, 8, 12 and 30 min.) to release glutamate. SGCs were then pre-incubated with BoNTA (24 hrs with 0.1, 1, 10 and 100 pM) to investigate if BoNTA could potentially block ionomycin-stimulated glutamate release. Glutamate concentrations were measured by ELISA. SNAP-25 and SNAP-23 were present in SGCs in TG sections and in cultured SGCs. Ionomycin significantly increased glutamate release from cultured SGCs 30 min. following the treatment (P < 0.001). BoNTA (100 pM) significantly decreased glutamate release (P < 0.01). Results from this study demonstrated that SGCs, when stimulated with ionomycin, released glutamate that was inhibited by BoNTA, possibly through cleavage of SNAP-25 and/or SNAP-23. These novel findings demonstrate the existence of vesicular glutamate release from SGCs, which could potentially play a role in the trigeminal sensory transmission. In addition, interaction of BoNTA with non-neuronal cells at the level of TG suggests a potential analgesic mechanism of action of BoNTA.
authors.affiliation: Center for Sensory - Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg East, Denmark.
authors.forename: Larissa Bittencourt
authors.initials: LB
authors.lastname: da Silva
authors.affiliation: Center for Sensory - Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg East, Denmark.
authors.forename: Jeppe Nørgaard
authors.initials: JN
authors.lastname: Poulsen
authors.affiliation: Center for Sensory - Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg East, Denmark.
authors.forename: Lars
authors.initials: L
authors.lastname: Arendt-Nielsen
authors.affiliation: Center for Sensory - Motor Interaction (SMI), Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg East, Denmark.|Laboratory for Cancer Biology, Biomedicine, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg East, Denmark.
authors.forename: Parisa
authors.initials: P
authors.lastname: Gazerani
mesh_terms: D000818:Animals; D019274:Botulinum Toxins, Type A / Q000494:pharmacology*; D002478:Cells, Cultured; D018698:Glutamic Acid / Q000378:metabolism*; D007150:Immunohistochemistry; D015759:Ionomycin / Q000494:pharmacology; D008297:Male; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism*; D017208:Rats, Wistar; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism*; D050825:Synaptosomal-Associated Protein 25 / Q000378:metabolism; D013997:Time Factors; D012668:Trigeminal Ganglion / Q000166:cytology / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: C498858:Snap23 protein, rat; D050825:Synaptosomal-Associated Protein 25; D033921:Vesicular Transport Proteins; D018698:Glutamic Acid; D015759:Ionomycin; D019274:Botulinum Toxins, Type A
keywords: SNAP-23; SNAP-25; botulinum neurotoxin type A; glutamate; ionomycin; pain; satellite glial cells; trigeminal ganglion; vesicular release