title: Modulation of recombinant GABA(A) receptors by neurosteroid dehydroepiandrosterone sulfate.
abstract: OBJECTIVE
  To investigate whether long-term exposure to the neurosteroid dehydroepiandrosterone sulfate (DHEAS) induces adaptive changes of GABA(A) receptors related to the development of tolerance and dependence.
  
  
  METHODS
  We compared the parameters of [(3)H]DHEAS binding and the effects of DHEAS on [(3)H]flunitrazepam binding in the membranes of HEK 293 cells, nontransfected or stably transfected with recombinant α(1)β(2)γ(2S) GABA(A) receptors. In HEK 293 cells expressing α(1)β(2)γ(2S) GABA(A) receptors, we investigated the effects of long-term DHEAS treatment on the [(3)H]flunitrazepam and [(3)H]t-butylbicycloorthobenzoate ([(3)H]TBOB) binding and on their modulation with GABA.
  
  
  RESULTS
  DHEAS behaves as an allosteric antagonist of the recombinant α(1)β(2)γ(2S) GABA(A) receptors expressed in HEK 293 cells. Exposure of cells to 100 μmol/l DHEAS for 48 h did not change the number or affinity of benzodiazepine and convulsive binding sites. Long-term DHEAS treatment failed to affect functional allosteric interactions between GABA(A) receptor binding sites, as evidenced by an unchanged ability of GABA to stimulate or to inhibit [(3)H]flunitrazepam and [(3)H]TBOB binding, respectively.
  
  
  CONCLUSIONS
  The findings that prolonged DHEAS treatment does not produce changes in GABA(A) receptor expression and functional coupling, assumed to underlie the development of tolerance and dependence, might have importance in the long-term therapy necessary for the observed beneficial effects of DHEAS.
authors.affiliation: Division of Molecular Medicine, Rudjer Boskovic Institute, University of Zagreb, Zagreb, Croatia.
authors.forename: Dubravka
authors.initials: D
authors.lastname: Svob Štrac
authors.forename: Maja
authors.initials: M
authors.lastname: Jazvinšćak Jembrek
authors.forename: Julija
authors.initials: J
authors.lastname: Erhardt
authors.forename: Kety
authors.initials: K
authors.lastname: Mirković Kos
authors.forename: Danka
authors.initials: D
authors.lastname: Peričić
mesh_terms: D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D019314:Dehydroepiandrosterone Sulfate / Q000494:pharmacology*; D005445:Flunitrazepam / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D011963:Receptors, GABA-A / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism*
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D011963:Receptors, GABA-A; D011994:Recombinant Proteins; D019314:Dehydroepiandrosterone Sulfate; D005445:Flunitrazepam; C046308:tert-butylbicyclo-2-benzoate