Premium
Capsaicin interacts with clathrin coated pit dependent mechanisms to protect motor nerve terminals against botulinum neurotoxin A
Author(s) -
Thyagarajan Baskaran,
Potian Joseph G,
Patel Vishwendra,
Garcia Carmen C,
Hognason Kormakur,
McArdle Joseph J
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.762.5
Subject(s) - capsaicin , chemistry , capsazepine , pharmacology , acetylcholine , trpv1 , neurotoxin , clathrin , microbiology and biotechnology , endocytosis , biophysics , biochemistry , biology , receptor , transient receptor potential channel
Botulinum neurotoxin A (BoNT/A) cleaves SNAP‐25 and terminates acetylcholine release at the motor nerve endings (MNEs) resulting in neuroparalysis. Recently, we reported that capsaicin, a TRPV1 channel agonist, protected MNEs from the inhibitory actions of BoNT/A (Thyagarajan et al 2009). This study examines the mechanisms of capsaicin's prophylactic action against BoNT/A. In control mice injection of BoNT/A (3 μl; 6.67 pM) near the innervations of the Extensor digitorum longus muscle of both hind limbs inhibited the toe spread reflex (TSR) within 24 hrs. However, when capsaicin (3 μl; 1 mM) was injected either 5 to10 minutes or 4 or 8 hours before BoNT/A, the TSR remained normal. Capsaicin pretreatment in vitro significantly reduced fluorescent BoNT/A uptake into MNEs and protected stimulus evoked twitch tension and acetylcholine release from MNEs while BoNT/A alone inhibited these motor nerve functions. Capsazepine, a TRPV1 antagonist prevented the protective effects of capsaicin. To understand the mechanism of capsaicin‐induced protection against BoNT/A, we studied cholinergic Neuro 2a cells. Acute exposure to capsaicin altered the subcellular localization of clathrin heavy chain (Chc) and AP2, two proteins essential to clathrin coated pit (CCP) formation. Chlorpromazine, an inhibitor of CCP dependent endocytosis (Maksymowych and Simpson, 2004), mimicked the effects of capsaicin on Chc delocalization. Wortmannin, (WMN, nonselective PI5K inhibitor), reduced fluorescent BoNT/A uptake into MNEs and delocalized Chc and AP2 in Neuro 2a cells. WMN (3 μl; 1 mM) injected 6 hours before BoNT/A protected mice from neuroparalysis. We hypothesize that capsaicin reduced the neuroparalytic effects of BoNT/A by inhibiting CCP dependent uptake of BoNT/A into MNEs.