1 research outputs found
Direct Modulation of Microtubule Stability Contributes to Anthracene General Anesthesia
Recently,
we identified 1-aminoanthracene as a fluorescent general
anesthetic. To investigate the mechanism of action, a photoactive
analogue, 1-azidoanthracene, was synthesized. Administration of 1-azidoanthracene
to albino stage 40–47 tadpoles was found to immobilize animals
upon near-UV irradiation of the forebrain region. The immobilization
was often reversible, but it was characterized by a longer duration
consistent with covalent attachment of the ligand to functionally
important targets. IEF/SDS-PAGE examination of irradiated tadpole
brain homogenate revealed labeled protein, identified by mass spectrometry
as β-tubulin. In vitro assays with aminoanthracene-cross-linked
tubulin indicated inhibition of microtubule polymerization, similar
to colchicine. Tandem mass spectrometry confirmed anthracene binding
near the colchicine site. Stage 40–47 tadpoles were also incubated
1 h with microtubule stabilizing agents, epothilone D or discodermolide,
followed by dosing with 1-aminoanthracene. The effective concentration
of 1-aminoanthracene required to immobilize the tadpoles was significantly
increased in the presence of either microtubule stabilizing agent.
Epothilone D similarly mitigated the effects of a clinical neurosteroid
general anesthetic, allopregnanolone, believed to occupy the colchicine
site in tubulin. We conclude that neuronal microtubules are “on-pathway”
targets for anthracene general anesthetics and may also represent
functional targets for some neurosteroid general anesthetics