Kobayashi T , Washiyama K , Ikeda K .

	Figure 1. Effects of pregnenolone sulfate (PREGS) on Kir2.3 channels expressed in Xenopus oocytes.(A) Upper row, in an oocyte injected with Kir2.3 mRNA, current responses to 30 µM PREGS and to 50 µM PREGS in the presence of 3 mM Ba2+ are shown. Lower row, in an uninjected oocyte, no significant current responses to 300 µM PREGS and 3 mM Ba2+ are shown. Current responses were measured at a membrane potential of −70 mV in an hK solution containing 96 mM K+. Asterisks show the zero current level. Horizontal bars show the duration of application. (B) Effects of various neurosteroids: PREG, PREGS, DHEA, DHEAS, progesterone (PROG), 17β-estradiol (E2), corticosterone (CORT), 3α-OH-DHP and THDOC, on Kir2.3 channels. The magnitudes of the effect of 100 µM neurosteroids on Kir2.3 channels were normalized to the 3 mM Ba2+-sensitive current components in oocytes expressing Kir2.3 channels (n≥4 for each steroid). Data are expressed as mean±SEM.
	Figure 2. Characteristics of Kir2.3 channel potentiation by PREGS.(A) Concentration-dependent effect of PREGS on Kir2.3 channels. The magnitudes of Kir2.3 currents potentiated by PREGS were normalized to the 3 mM Ba2+-sensitive current components in Xenopus oocytes expressing Kir2.3 channels (554.0±79.9 nA, n = 6). Data are expressed as mean±SEM of the percentage responses. (B) Correlation between amplitudes of current response to 30 µM PREGS and amplitudes of the 3 mM Ba2+-sensitive current components in oocytes expressing Kir2.3 channels. The correlation coefficient was 0.894 (P<0.05, n = 22, regression analysis). Current responses were measured at a membrane potential of −70 mV in an hK solution containing 96 mM K+. (C) Representative Kir2.3 currents elicited by a voltage step to −100 mV for 2 s from a holding potential of 0 mV in the presence or absence of 30 µM PREGS in an oocyte injected with Kir2.3 mRNA. Arrow indicates the zero current level. (D) Current-voltage relationships of 3 mM Ba2+-sensitive currents and 30 µM PREGS-enhanced currents in oocytes expressing Kir2.3 channels. Current responses were normalized to the 3 mM Ba2+-sensitive current component measured at a membrane potential of −100 mV (1510.0±209.9 nA, n = 6).
	Figure 3. Effect of intracellular PREGS in Xenopus oocytes expressing Kir2.3 channels.(A) Comparison of basal Kir2.3 currents before and after PREGS injection in oocytes expressing Kir2.3 channels. The amplitude of Kir2.3 currents was normalized to the amplitude of 3 mM Ba2+-sensitive current components before PREGS injection. (B) Comparison of 50 µM PREGS-induced Kir2.3 currents before and after PREGS injection. Data are expressed as mean±SEM.
	Figure 4. Effects of PREG and DHEAS on PREGS-induced Kir2.3 currents.(A) Representative current responses to 30 µM PREGS and to 30 µM PREGS in the presence of 100 µM PREG in a Xenopus oocyte expressing Kir2.3 channels. Current responses were measured at a membrane potential of −70 mV in an hK solution containing 96 mM K+. (B) Comparison of PREGS-induced Kir2.3 currents in the presence or absence of PREG or DHEAS. Concentrations of PREGS, PREG, and DHEAS were 30, 100, and 100 µM, respectively. Current responses to PREGS in the presence of PREG or DHEAS were normalized to the amplitude of PREGS-induced currents in the absence of PREG or DHEAS (control). Data are expressed as mean±SEM.
	Figure 5. Concentration-response relationships for potentiation of Kir2.3 channels by PREGS at different pH values.The magnitudes of potentiation of Kir2.3 currents by PREGS in oocytes expressing Kir2.3 channels were normalized to the 3 mM Ba2+-sensitive current components, which were 426.9.6±41.4 nA (pH 6.0), 554.0±79.9 nA (pH 7.4) and 729.2±36.6 nA (pH 9.0). The EC50 and nH values were 16.1±1.2 µM and 1.44±0.07 (pH 6.0, n = 10), 15.6±0.9 µM and 1.43±0.03 (pH 7.4, n = 6), and 17.1±1.5 µM and 0.70±0.03 (pH 9.0, n = 8), respectively. Current responses were measured at a membrane potential of −70 mV in an hK solution containing 96 mM K+. Data are expressed as mean±SEM of the percentage responses.
	Figure 6. Comparison of the effects of PREGS on Kir1.1, Kir2.1, Kir2.2, Kir2.3, and Kir3 channels expressed in Xenopus oocytes.The magnitudes of change in Kir currents by 100 µM PREGS were normalized to the 3 mM Ba2+-sensitive current components. For Kir3 channels, oocytes expressing brain-type Kir3.1/Kir3.2 channels were used. Current responses were measured at a membrane potential of −70 mV in an hK solution containing 96 mM K+. Data are expressed as mean±SEM.
	Figure 7. Comparison of the potentiation effects of PREGS on Kir2.3, Kir2.1/Kir2.3, and Kir2.2/Kir2.3 channels expressed in Xenopus oocytes.Responses to PREGS at different concentrations were normalized to the maximal response to PREGS. Current responses were measured at a membrane potential of −70 mV. Data are expressed as mean±SEM.

Akwa, Neurosteroids in rat sciatic nerves and Schwann cells. 1993, Pubmed

Akwa, Neurosteroids in rat sciatic nerves and Schwann cells. 1993, Pubmed
Barbaccia, Time-dependent changes in rat brain neuroactive steroid concentrations and GABAA receptor function after acute stress. 1996, Pubmed
Baulieu, Neurosteroids: beginning of the story. 2001, Pubmed
Bicíková, Serum concentrations of some neuroactive steroids in women suffering from mixed anxiety-depressive disorder. 2000, Pubmed
Caldeira, Fetal alcohol exposure alters neurosteroid levels in the developing rat brain. 2004, Pubmed
Chen, Intradermal pregnenolone sulfate attenuates capsaicin-induced nociception in rats. 2006, Pubmed
Cohen, Binding of the inward rectifier K+ channel Kir 2.3 to PSD-95 is regulated by protein kinase A phosphorylation. 1996, Pubmed
Corpéchot, Pregnenolone and its sulfate ester in the rat brain. 1983, Pubmed
Coulter, Identification and molecular localization of a pH-sensing domain for the inward rectifier potassium channel HIR. 1995, Pubmed , Xenbase
Doupnik, The inward rectifier potassium channel family. 1995, Pubmed
Havlíková, Sex- and age-related changes in epitestosterone in relation to pregnenolone sulfate and testosterone in normal subjects. 2002, Pubmed
Higashi, Studies on neurosteroids XVI. Levels of pregnenolone sulfate in rat brains determined by enzyme-linked immunosorbent assay not requiring solvolysis. 2003, Pubmed
Hill, Neuroactive steroids, their precursors and polar conjugates during parturition and postpartum in maternal and umbilical blood: 3.3beta-hydroxy-5-ene steroids. 2002, Pubmed
Hill, Altered profiles of serum neuroactive steroids in premenopausal women treated for alcohol addiction. 2005, Pubmed
Ho, Cloning and expression of an inwardly rectifying ATP-regulated potassium channel. 1993, Pubmed , Xenbase
Ikeda, Opioid receptor coupling to GIRK channels. In vitro studies using a Xenopus oocyte expression system and in vivo studies on weaver mutant mice. 2003, Pubmed , Xenbase
Inanobe, Inward rectifier K+ channel Kir2.3 is localized at the postsynaptic membrane of excitatory synapses. 2002, Pubmed
Iwamori, Steroid sulfatase in brain: comparison of sulfohydrolase activities for various steroid sulfates in normal and pathological brains, including the various forms of metachromatic leukodystrophy. 1976, Pubmed
Karschin, IRK(1-3) and GIRK(1-4) inwardly rectifying K+ channel mRNAs are differentially expressed in the adult rat brain. 1996, Pubmed
Kimoto, Neurosteroid synthesis by cytochrome p450-containing systems localized in the rat brain hippocampal neurons: N-methyl-D-aspartate and calcium-dependent synthesis. 2001, Pubmed
Kobayashi, Functional characterization of an endogenous Xenopus oocyte adenosine receptor. 2002, Pubmed , Xenbase
Kobayashi, Ethanol opens G-protein-activated inwardly rectifying K+ channels. 1999, Pubmed , Xenbase
Kobayashi, Inhibition of G protein-activated inwardly rectifying K+ channels by fluoxetine (Prozac). 2003, Pubmed , Xenbase
Kobayashi, Inhibition by various antipsychotic drugs of the G-protein-activated inwardly rectifying K(+) (GIRK) channels expressed in xenopus oocytes. 2000, Pubmed , Xenbase
Kobayashi, Molecular cloning of a mouse G-protein-activated K+ channel (mGIRK1) and distinct distributions of three GIRK (GIRK1, 2 and 3) mRNAs in mouse brain. 1995, Pubmed
Koyama, Molecular cloning, functional expression and localization of a novel inward rectifier potassium channel in the rat brain. 1994, Pubmed , Xenbase
Kubo, Primary structure and functional expression of a mouse inward rectifier potassium channel. 1993, Pubmed , Xenbase
Le Maout, Basolateral membrane targeting of a renal-epithelial inwardly rectifying potassium channel from the cortical collecting duct, CCD-IRK3, in MDCK cells. 1997, Pubmed , Xenbase
Liu, Direct activation of an inwardly rectifying potassium channel by arachidonic acid. 2001, Pubmed
Liu, Tenidap, a novel anti-inflammatory agent, is an opener of the inwardly rectifying K+ channel hKir2.3. 2002, Pubmed
Liu, Neurosteroids in rat brain: extraction, isolation, and analysis by nanoscale liquid chromatography-electrospray mass spectrometry. 2003, Pubmed
Mameli, Neurosteroid-induced plasticity of immature synapses via retrograde modulation of presynaptic NMDA receptors. 2005, Pubmed
Mayo, Pregnenolone sulfate and aging of cognitive functions: behavioral, neurochemical, and morphological investigations. 2001, Pubmed
Mellon, Neurosteroids: biochemistry and clinical significance. 2002, Pubmed
Melnyk, Differential distribution of Kir2.1 and Kir2.3 subunits in canine atrium and ventricle. 2002, Pubmed
Mi, Inwardly rectifying K+ channels that may participate in K+ buffering are localized in microvilli of Schwann cells. 1996, Pubmed
Morfin, Neurosteroids: pregnenolone in human sciatic nerves. 1992, Pubmed
Muñoz, Kir2.3 isoform confers pH sensitivity to heteromeric Kir2.1/Kir2.3 channels in HEK293 cells. 2007, Pubmed , Xenbase
Nguyen, Increased allopregnanolone levels in the fetal sheep brain following umbilical cord occlusion. 2004, Pubmed
Park, Distribution and characterization of neurosteroid sulfatase from the bovine brain. 1997, Pubmed
Preisig-Müller, Heteromerization of Kir2.x potassium channels contributes to the phenotype of Andersen's syndrome. 2002, Pubmed , Xenbase
Prüss, Differential distribution of individual subunits of strongly inwardly rectifying potassium channels (Kir2 family) in rat brain. 2005, Pubmed
Périer, Primary structure and characterization of a small-conductance inwardly rectifying potassium channel from human hippocampus. 1994, Pubmed , Xenbase
Reddy, Chronic neurosteroid treatment prevents the development of morphine tolerance and attenuates abstinence behavior in mice. 1997, Pubmed
Reddy, Differential anxiolytic effects of neurosteroids in the mirrored chamber behavior test in mice. 1997, Pubmed
Reddy, Neurosteroid coadministration prevents development of tolerance and augments recovery from benzodiazepine withdrawal anxiety and hyperactivity in mice. 1997, Pubmed
Reddy, Sigma (sigma1) receptor mediated anti-depressant-like effects of neurosteroids in the Porsolt forced swim test. 1998, Pubmed
Reimann, Inwardly rectifying potassium channels. 1999, Pubmed
Rupprecht, Neuroactive steroids: mechanisms of action and neuropsychopharmacological perspectives. 1999, Pubmed
Schram, Barium block of Kir2 and human cardiac inward rectifier currents: evidence for subunit-heteromeric contribution to native currents. 2003, Pubmed , Xenbase
Shirakawa, Pregnenolone sulphate attenuates AMPA cytotoxicity on rat cortical neurons. 2005, Pubmed
Steckelbroeck, Steroid sulfatase (STS) expression in the human temporal lobe: enzyme activity, mRNA expression and immunohistochemistry study. 2004, Pubmed
Stonehouse, Characterisation of Kir2.0 proteins in the rat cerebellum and hippocampus by polyclonal antibodies. 1999, Pubmed
Tagawa, Serum dehydroepiandrosterone, dehydroepiandrosterone sulfate, and pregnenolone sulfate concentrations in patients with hyperthyroidism and hypothyroidism. 2000, Pubmed
Takahashi, Molecular cloning and functional expression of cDNA encoding a second class of inward rectifier potassium channels in the mouse brain. 1994, Pubmed , Xenbase
Torres, DHEA, PREG and their sulphate derivatives on plasma and brain after CRH and ACTH administration. 2003, Pubmed
Töpert, Kir2.4: a novel K+ inward rectifier channel associated with motoneurons of cranial nerve nuclei. 1998, Pubmed , Xenbase
Ureche, Novel insights into the structural basis of pH-sensitivity in inward rectifier K+ channels Kir2.3. 2008, Pubmed , Xenbase
Vallée, Neurosteroids: deficient cognitive performance in aged rats depends on low pregnenolone sulfate levels in the hippocampus. 1997, Pubmed
Wagner, Transient receptor potential M3 channels are ionotropic steroid receptors in pancreatic beta cells. 2008, Pubmed
Wang, Modulation of cloned human neuronal voltage-gated potassium channels (hKv1.1 and hKv2.1) by neurosteroids. 1998, Pubmed
Wang, The regional brain distribution of the neurosteroids pregnenolone and pregnenolone sulfate following intravenous infusion. 1997, Pubmed
Williamson, Characterization of the convulsant action of pregnenolone sulfate. 2004, Pubmed
Yan, Effects of morphine dependence and withdrawal on levels of neurosteroids in rat brain. 2004, Pubmed
de Peretti, Usefulness of plasma pregnenolone sulfate in testing pituitary-adrenal function in children. 1986, Pubmed
ffrench-Mullen, Neurosteroids modulate calcium currents in hippocampal CA1 neurons via a pertussis toxin-sensitive G-protein-coupled mechanism. 1994, Pubmed