1 research outputs found
The role of diacylglycerol lipase in constitutive and angiotensin AT(1) receptor-stimulated cannabinoid CB1 receptor activity
The cannabinoid CB1 receptor (CB1R) is,a G protein-coupled receptor,
which couples to the G(i/o) family of heterotrimeric G proteins. The
receptor displays both basal and agonist-induced signaling and
internalization. Although basal activity of CBIRs is attributed to
constitutive (agonist-independent) receptor activity, studies in
neurons suggested a role of postsynaptic endocannabinoid (eCB) release
in the persistent activity of presynaptic CB1Rs. To elucidate the role
of eCBs in basal CB1R activity, we have investigated the role of
diacylglycerol lipase (DAGL) in this process in Chinese hamster ovary
(CHO) cells, which are not targeted specifically with I Agonist-induced
G protein activation was determined by detecting dissociation G protein
subunits expressed in CHO cells with bioluminescence resonance energy
transfer (BRET), after labeling the alpha and beta subunits with
Renilla luciferase and enhanced yellow fluorescent protein (EYFP),
respectively. Pre-incubation of the cells with tetrahydrolipstatin
(THL), a known inhibitor of DAGLs, caused inhibition of the basal
activity of CBIR. Moreover, preincubation of CHO and cultured
hippocampal neurons with THL increased the number of CBIRs on the cell
membrane, which reflects its inhibitory action on CB1R internalization
in non-simulated cells. In CHO cells co-expressing CB1R and angiotensin
AT(1) receptors, angiotensin II-induced Go protein activation that was
blocked by both a CBIR antagonist and THL. These data indicate that
cell-derived I mediators have a general role in the basal activity of
CB1Rs in non-neural cells and neurons, and that this mechanism can be
stimulated by AT(1) receptor activation