Fig. 2: KOR dependent upstream and downstream molecular signaling pathway effects of oxa-iboga compounds.
From: Oxa-Iboga alkaloids lack cardiac risk and disrupt opioid use in animal models
a Illustration of the KOR-induced molecular signaling pathway assays in vitro and in vivo. The location and shape of medial prefrontal cortex (mPFC), nucleus accumbens (NAc) and ventral tegmental area (VTA) are highlighted in a rodent brain - representative illustration of a left hemisphere (sagittal slice, mouse, Allen Institute99). b Oxa-iboga compounds are agonists of rat KOR in vitro, as demonstrated by a G protein activation BRET assay. c Oxa-noribogaine displays signaling efficacy across Gα isoforms, efficacy compared to U50,488 in the TRUPATH BRET assay. Pooled data (n = 3 biological replicates) for each subunit were analyzed using a nonlinear regression and the calculated span ± SEM parameters are presented (dose response curves Supplementary Fig. S6). d In the nanobody Nb33 sensor recruitment assay, which approximates true intrinsic signaling efficacy, oxa-noribogaine analogs are partial agonists. e Additionally, markedly reduced signaling efficacy for oxa-noriboga analogs was detected in the β-arrestin2 recruitment assay (KOR results on panels b, d, e are presented as mean ± SEM, n = 3 biological replicates). f Administration of oxa-noribogaine (40 mg/kg; i.p.) significantly increased GDNF protein levels in the mPFC and VTA after 5 days (OXA5). Pre-treatment of rats with KOR selective antagonist aticaprant (ATI, 1 mg/kg s.c.) before oxa-noribogaine administration prevents the increase of GDNF expression in mPFC and VTA. mPFC: CONTROL - OXA5 (P < 0.0001), VEH + VEH - OXA5 (P = 0.0078), VEH + ATI - OXA5 (P = 0.0123), OXA5 - ATI + OXA5 (P = 0.0022) and VTA: CONTROL - OXA5 (P = 0.0010), VEH + VEH - OXA5 (P = 0.0004), VEH + ATI - OXA5 (P < 0.0001), OXA5 - ATI + OXA5 (P = 0.0001). Experiments were conducted using separate groups of animals (Control n = 7, all other groups n = 8 subjects). Data are presented as mean ± SEM. Statistical test used: One-way ANOVA with Tukey’s multiple comparisons test, *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. Source data are provided in the Source Data file.
