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. 2022 Nov 15;11:e81298. doi: 10.7554/eLife.81298

Figure 3. Partial and biased MOR agonists fail to elicit tolerance to the same degree as full agonists peptides.

Figure 3.

(A) Same experimental setup as in Figure 2, except the agonist used was morphine 10 μM (n=8 acquisitions), control replotted from Figure 2B. Inset show images of VPS29-GFP and surface labeled SSF-MOR after 25–30 min of incubation with morphine 10 μM. (B) DAMGO induced MOR inhibition exhibits tolerance after incubation with morphine 10 μM+DMSO vehicle (inset n=3,400 synapses, n=21 acquisitions) and tolerance is blocked by incubation of morphine 10 μM together with Cmpd101 30 μM (inset n=2441 synapses, n=19 acquisitions). Acute condition replotted from Figure 1C, DMSO +DAMGO condition replotted from Figure 2H. (C) Morphine 10 μM+DMSO (n=2076 synapses) induces a loss of surface SEP-MOR in axons after 18 hr of incubation compared to DMSO only control (replotted from Figure 2I). The loss is less pronounced than when induced by incubation by DAMGO 10 μM+DMSO (replotted from Figure 2I) for 18 hr, and is blocked by incubation of DAMGO 10 μM together with Cmpd101 30 μM (n=2872 synapses). Syp-mCh signal is similar across conditions. (D) Same as A except cells were stimulated with PZM21 10 μM (n=5 acquisitions). Note the diffuse distribution of surface labeled SSF-MOR after 25–30 min of incubation with PZM21 10 μM. (E) Same as for B for cells incubated for 18 hours with PZM21 10 μM together with Cmpd101 30 μM for 18 hr (inset n=883 synapses, n=8 acquisitions) or DMSO vehicle (inset n=1089 synapses, n=8 acquisitions). Acute condition replotted from Figure 1C. (F) Same as A except cells were stimulated with TRV130 10 μM (n=5 acquisitions). Note the diffuse distribution of surface labeled SSF-MOR after 25–30 min of incubation with TRV130 10 μM. (G) Same as for B for cells incubated for 18 hr with TRV130 10 μM together with Cmpd101 30 μM for 18 hr (inset n=1,076 synapses, n=7 acquisitions) or DMSO vehicle (inset n=1280 synapses, n=8 acquisitions). Acute condition replotted from Figure 1C. Scale bars are 5 μm. **, *** represent p<0.01, 0.001, respectively. See also Figure 3—source data 1.

Figure 3—source data 1. Source data for results graphed in Figure 3.
elife-81298-fig3-data1.xlsx (455.2KB, xlsx)