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Neurosteroids differentially modulate P2X 4 ATP‐gated channels through non‐genomic interactions
Author(s) -
Codocedo Juan Francisco,
Rodríguez Felipe E.,
HuidobroToro Juan Pablo
Publication year - 2009
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2009.06166.x
Subject(s) - neuroactive steroid , pregnanolone , receptor , allopregnanolone , homomeric , pregnenolone sulfate , allosteric modulator , endocrinology , medicine , xenopus , ion channel , chemistry , pregnenolone , hek 293 cells , patch clamp , gabaa receptor , biology , biochemistry , allosteric regulation , steroid , hormone , protein subunit , gene
As neuroactive steroids modulate several ionotropic receptors, we assessed whether the ATP‐gated currents elicited by P2X 4 receptors are modulated by these compounds. We transfected HEK293 cells or injected Xenopus laevis oocytes with the cDNA coding for rat P2X 4 receptor. Application of 0.1–10 μM alfaxolone potentiated within 60‐s the 1 μM ATP‐evoked currents with a maximal potentiation of 1.8 and 2.6‐fold in HEK293 or oocytes cells respectively. Allopregnalolone or 3α, 21‐dihydroxy‐5α‐pregnan‐20‐one (THDOC) also potentiated the ATP‐gated currents but with a maximal effect only averaging 1.25 and 1.35‐fold respectively. In contrast, 0.3–10 μM pregnanolone, but not its sulfated derivative, inhibited the ATP‐gated currents; the maximal inhibition reached 40% in both cell types. THDOC, but not other neurosteroids increased significantly the τ off of the ATP‐evoked currents, revealing another mode of neurosteroid modulation. Sexual steroids such as 17β‐estradiol or progesterone were inactive revealing explicit structural requirements. Alfaxolone or THDOC at concentrations 30‐ to 100‐fold larger than required to modulate the receptor, gated the P2X 4 receptor eliciting ATP‐like currents that were reduced with suramin or brilliant blue G, but potentiated the P2X 4 receptor more than 10‐fold by 10 μM zinc. In conclusion, neurosteroids rapidly modulate via non‐genomic mechanisms and with nanomolar potencies, the P2X4 receptor interacting likely at distinct modulator sites.