Flurazepam modulates gating of spontaneous and agonist-evoked GABAA receptor activity via distinct mechanisms

• Autorzy: Jatczak-Sliwa M. , Terejko K. , Brodzki M. , Michalowski M.A. , Czyzewska M.M. , Nowicka J.M. , Andrzejczak A. , Srinivasan R. , Mozrzymas J.W.
• Języki publikacji: EN

Abstrakty

EN

GABAA receptors mediate inhibitory transmission in the adult mammalian brain and are modulated by many clinically used drugs such as benzodiazepines. It has pre‑ viously been demonstrated that benzodiazepines affect binding and gating transitions. However, the mechanism of their modulation is still not fully understood. In our present study we address this problem by examining modulation of spontaneous activity by the benzodiaz‑ epine flurazepam and its cross-talk with ligand-evoked activity of wild-type and mutated (at α1F64 position lo‑ cated in the GABA-binding site, shown to affect preac‑ tivation/flipping transition) α1β2γ2 GABAA receptors. We used patch-clamp technique to measure macroscop‑ ic and single-channel currents mediated by wild-type and mutated (Leu, Ala or Cys substitution at the α1F64 position) GABAA receptors. Spontaneous activity was measured using a BioLogic Perfusion System and picro‑ toxin application. We also performed experiments for saturating GABA and partial agonist applications using an ultrafast perfusion system (theta-glass). We used flu‑ razepam pretreatment and co-application (flurazepam with GABA) protocols, which allowed us to observe the cross-talk between spontaneous and ligand-induced ac‑ tivity. Model simulations were performed in ChaneLab software. α1F64 mutants exhibited larger spontaneous activity compared to wild-type receptors and fluraze‑ pam potentiated this activity to the same extent for all considered receptor types. Our single-channel analysis showed prolonged openings upon flurazepam treat‑ ment. For saturating [GABA] applications in a pretreat‑ ment protocol, we found a significant correlation be‑ tween the increase of the overshoot (amplitude above the baseline after agonist removal) and the amplitude of currents upon flurazepam application. Flurazepam po‑ tentiates the amplitude of currents mediated by mutants after GABA and partial agonist application and affects their kinetics. Our model simulations indicate that flu‑ razepam affects opening/closing transitions of sponta‑ neous activity but affects preactivation and desensitiza‑ tion transitions of ligand-induced activity. Flurazepam’s mechanism of GABAA receptor modulation is different for spontaneous and ligand-induced activity. Moreover, spontaneous openings clearly affect agonist-evoked re‑ sponses. Altogether, flurazepam alters the GABAA re‑ ceptor gating transitions in a manner dependent on the receptor ligation. Supported by NCN grants: 2013/11/B/ NZ3/00983 and 2015/18/A/NZ1/00395.

• Wydawca: -
• Czasopismo: Acta Neurobiologiae Experimentalis
• Rocznik: 2018
• Tom: 78
• Numer: Suppl.1
• Opis fizyczny: p.8-9

Twórcy

autor

Jatczak-Sliwa M.

• Department of Molecular Physiology and Neurobiology, Wroclaw University, Wroclaw, Poland
• Laboratory of Neuroscience, Department of Biophysics, Wroclaw Medical University, Wroclaw, Poland

autor

Terejko K.

• Laboratory of Neuroscience, Department of Biophysics, Wroclaw Medical University, Wroclaw, Poland

autor

Brodzki M.

• Department of Molecular Physiology and Neurobiology, Wroclaw University, Wroclaw, Poland
• Laboratory of Neuroscience, Department of Biophysics, Wroclaw Medical University, Wroclaw, Poland

autor

Michalowski M.A.

• Department of Molecular Physiology and Neurobiology, Wroclaw University, Wroclaw, Poland
• Laboratory of Neuroscience, Department of Biophysics, Wroclaw Medical University, Wroclaw, Poland

autor

Czyzewska M.M.

• Laboratory of Neuroscience, Department of Biophysics, Wroclaw Medical University, Wroclaw, Poland

autor

Nowicka J.M.

• Laboratory of Neuroscience, Department of Biophysics, Wroclaw Medical University, Wroclaw, Poland

autor

Andrzejczak A.

• Department of Molecular Physiology and Neurobiology, Wroclaw University, Wroclaw, Poland
• Laboratory of Neuroscience, Department of Biophysics, Wroclaw Medical University, Wroclaw, Poland

autor

Srinivasan R.

• Department of Molecular Physiology and Neurobiology, Wroclaw University, Wroclaw, Poland
• Laboratory of Neuroscience, Department of Biophysics, Wroclaw Medical University, Wroclaw, Poland

autor

Mozrzymas J.W.

• Laboratory of Neuroscience, Department of Biophysics, Wroclaw Medical University, Wroclaw, Poland