The effect of propofol on actin, ERK-1/2 and GABAA receptor content in neurones.
OBJECTIVE
Interaction with the gamma-aminobutyric acid receptor (GABA(A)R) complex is recognized as an important component of the mechanism of many anaesthetic agents, including propofol. The aims of this study were to investigate the effect of propofol on GABA(A)R, to determine whether exposure of neurones to propofol influences the localization of GABA(A)R within the cell and to look for cytoskeletal changes that may be connected with activation, such as the mitogen-activated protein kinase (MAPK) pathway.


METHODS
Primary cortical cell cultures from rat, with and without pre-incubation with the GABA(A)R antagonist bicuculline, were exposed to propofol. The cells were lysed and separated into membrane and cytosolic fractions. Immunoblot analyses of filamentous actin (F-actin), the GABA(A)beta(2)-subunit receptor and extracellular signal-regulated kinase-1/2 (ERK-1/2) were performed.


RESULTS
Propofol triggers an increase in GABA(A)R, actin content and ERK-1/2 phosphorylation in the cytosolic fraction. In the membrane fraction, there is a decrease in GABA(A)beta(2)-subunit content and an increase in both actin content and ERK-1/2 phosphorylation. The GABA(A)R antagonist bicuculline blocks the propofol-induced changes in F-actin, ERK and GABA(A)beta(2)-subunit content, and ERK-1/2 phosphorylation.


CONCLUSIONS
We believe that propofol triggers a dose-dependent internalization of the GABA(A)beta(2)-subunit. The increase in internal GABA(A)beta(2)-subunit content exhibits a close relationship to actin polymerization and to an increase in ERK-1/2 activation. Actin contributes to the internalization sequestering of the GABA(A)beta(2)-subunit.
Oscarsson
A
A
Department of Anaesthesia/Intensive Care, Linköping University Hospital, Linköping, Sweden.
Juhas
M
M
Sjölander
A
A
Eintrei
C
C
D000199:Actins / Q000187:drug effects*; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000187:drug effects* / Q000378:metabolism; D018756:GABA Antagonists / Q000494:pharmacology; D009474:Neurons / Q000737:chemistry / Q000187:drug effects*; D015742:Propofol / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000187:drug effects* / Q000378:metabolism
D000199:Actins; D018686:Anesthetics, Intravenous; D018756:GABA Antagonists; D011963:Receptors, GABA-A; D048049:Extracellular Signal-Regulated MAP Kinases; D001640:Bicuculline; D015742:Propofol