Tribuiani N, de Souza J, de Queiroz Junior MA, Baldo DA, de Campos Orsi V, Oshima-Franco Y. Effects Of Doxycycline On Mice Neuromuscular Junction, In Situ.
Curr Mol Med 2021;
22:349-353. [PMID:
34355683 DOI:
10.2174/1566524021666210521125553]
[Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 02/17/2021] [Accepted: 02/26/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND
The antibacterial mechanism of doxycycline is known, but on the nerve-muscle apparatus is yet unclear.
OBJECTIVE
To combine molecular targets of the neuromuscular machinery using the neuronal blocker effect doxycycline, a semisynthetic second-generation tetracycline derivative, on mice neuromuscular preparations, in situ.
METHODS
Doxycycline was assessed at the neurotransmission; presynaptic; synaptic cleft; and postsynaptic, including the muscle fiber, using the traditional myographic technique. Preliminarily, doxycycline showed an "all or nothing" effect, being "all" obtained with 4 µM and "nothing", with 1-3 µM. The rationale of this study was to apply known pharmacological tools against the blocker effect of 4 µM doxycycline such as F55-6 (Casearia sylvestris), CaCl2 (or Ca2+), atropine, neostigmine, polyethylene glycol (PEG 400), and d-Tubocurarine. The evaluation of cholinesterase enzyme activity, the diaphragm muscle histology, and protocols on the neuromuscular preparation submitted to indirect or direct stimuli were complementary.
RESULTS
Doxycycline does not affect cholinesterase activity nor cause damage to skeletal muscle diaphragm; acts on ryanodine receptor, sarcolemmal membrane, and on neuronal sodium channel with a postjunctional consequence due to the decreased availability of muscle nicotinic acetylcholine receptors.
CONCLUSIONS
In conclusion, using the blocker effect we showed that doxycycline acts on multiple targets, among them, is antagonized by F55-6, a neuronal Na+-channel agonist and Ca2+, but not by neostigmine.
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