Effects of anesthetic agents on focal adhesion kinase (pp125FAK) tyrosine phosphorylation in rat hippocampal slices.
BACKGROUND
Tyrosine protein kinase proteins exert a prominent control on signaling pathways and may couple rapid events, such as action potential and neurotransmitter release, to long-lasting changes in synaptic strength and survival. Whether anesthetics modulate tyrosine kinase activity remains unknown. The aim of the current study was therefore to examine the effects of intravenous and volatile anesthetics on the phosphorylation of focal adhesion kinase (ppFAK), a functionally important nonreceptor tyrosine kinase, in the rat hippocampus.


METHODS
Phosphorylation of ppFAK was examined in hippocampal slices by immunoblotting with both antiphosphotyrosine and specific anti-ppFAK antibodies. Experiments were performed in the absence (control) or presence of various concentrations of pharmacologic or anesthetic agents or both.


RESULTS
Clinically relevant concentrations of thiopental, propofol, etomidate, isoflurane, sevoflurane, and desflurane induced a concentration-related increase in tyrosine phosphorylation. In contrast, ketamine (up to 100 microm) and the nonimmobilizer F6 (1,2-dichlorohexafluorocyclobutane, 25 microm) did not significantly affect ppFAK phosphorylation. The anesthetic-induced increase in ppFAK phosphorylation was blocked by GF 109203X, RO 318220, and chelerythrin (100 microm), three structurally distinct inhibitors of protein kinase C and U 73122 (50 microm), an inhibitor of phospholipase C. The propofol- and isoflurane-induced increase in ppFAK phosphorylation was reversible and showed nonadditivity of effects with phorbol 12-myristate 13-acetate (an activator of protein kinase C, 0.1 microm). In contrast, ketamine (up to 100 microm), MK801 (10 microm, an N-methyl-d-aspartate receptor antagonist), bicuculline (10 microm, a gamma-aminobutyric acid type A receptor antagonist), and dantrolene (30 microm, an inhibitor of the ryanodine receptor) were ineffective in blocking anesthetic-induced activation of tyrosine phosphorylation.


CONCLUSIONS
Except for ketamine, anesthetic agents markedly increase tyrosine phosphorylation of ppFAK in the rat hippocampus, most likely via the phospholipase C-protein kinase C pathway, whereas the nonimmobilizer F6 does not. These results suggest that ppFAK represents a target for anesthetic action in the brain.
Bichat University Hospital, Paris, France.
Souhayl
S
Dahmani
Antoine
A
Tesnière
Danielle
D
Rouelle
Madeleine
M
Toutant
Jean-Marie
JM
Desmonts
Jean
J
Mantz
D000777:Anesthetics / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D006624:Hippocampus / Q000187:drug effects* / Q000201:enzymology*; D015151:Immunoblotting; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors; D014443:Tyrosine / Q000378:metabolism*
D000777:Anesthetics; D018685:Anesthetics, Inhalation; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D011493:Protein Kinase C; D010738:Type C Phospholipases; D013755:Tetradecanoylphorbol Acetate