Protease-activated receptor-1 (PAR1) / Gα-protein coupling in the amygdala is dynamic and regulated by fear learning.

To assess whether fear conditioning alters PAR1 Gα-protein binding in the amygdala we performed [35S] GTPγS binding and Gα-specific immunoprecipitation assay.

(a) TRag-induced increases in [35S] GTPγS binding to Gαo and Gαq / 11 were abolished in PAR1 - / - animals, confirming assay specificity. (b) Western blotting demonstrated that fear conditioning did not affect cellular Gαo or Gαq / 11 levels.

(c) Stimulation of PAR1 in PAR1 + / + mice with TRag revealed a fear-conditioning-specific twofold increase in PAR1 Gαo coupling while Gαq / 11 coupling was unaffected. The unpaired protocol did not change PAR1 – G protein association.

Fear conditioning-induced shift towards inhibitory Gαo binding of PAR1 was consistent with greater inductions of c-Fos (d) and phospho-CREB (cAMP response element-binding protein) (e) in the basal nucleus of the amygdala of PAR1 - / - mice after conditioning. * P <0.05, ** P <0.01. Data are shown as means ± s.e.m. (d, e) Bar = 100 μm Download Power Point slide (355 KB)