Journal: bioRxiv

Article Title: Valine Engages a Prefrontal mGluR5 Allosteric Site to Preserve Social Behavior

doi: 10.64898/2026.10.14.759089

Figure Lengend Snippet: (A) Schematic of the PRESTO-Tango β-arrestin recruitment assay used to quantify mGluR5 activation through transcriptional reporter output. Ligand-induced β-arrestin recruitment drives TEV-dependent release of a tethered transcription factor, leading to luciferase reporter expression. (B) PRESTO-Tango responses evoked by glutamate, valine, leucine and isoleucine at the indicated concentrations (0, 1, 10 and 100 μM). Dots indicate independent wells or measurements; n = 8 per condition. (C and D) Effects of the competitive orthosteric mGluR antagonist MCPG on PRESTO-Tango responses driven by glutamate (C) or valine (D). n = 9–10 per condition. (E) Schematic of the electrophysiological assay used to report canonical mGluR5–Gq–PLC signaling through TRPC3 currents in a heterologous system. (F) Representative whole-cell recordings. Top, 100 μM valine does not evoke detectable TRPC3 current, whereas 1 μM glutamate evokes a robust inward current. Bottom, pre-application of 1 μM valine enhances the response to subthreshold glutamate (0.1 μM). (G) Quantification of valine-dependent potentiation of subthreshold glutamate-evoked TRPC3 currents, expressed as a normalized current ratio ( I / I 0 ; see Methods). n = 5 cells per group. (H) Concentration–response relationship for valine-dependent potentiation, with EC 50 indicated. (I) Experimental design for behavioural rescue with intra-mPFC infusion of the mGluR5 agonist CHPG before three-chamber testing in control and Bckdk ΔmPFC mice. (J) Three-chamber performance shown as time spent in the social chamber (S1) versus the empty chamber (EM) and as social preference index. n = 13, 10, and 11 mice per group, as shown. (K) Experimental design for testing pharmacological constraints on valine-mediated rescue. Bckdk ΔmPFC mice received vehicle or valine, alone or together with the mGluR5 negative allosteric modulator MPEP or the competitive mGluR antagonist MCPG, before the sociability assay. (L) Three-chamber performance for the conditions in (K). n = 8–10 mice per group, as shown. Data are mean ± s.e.m. In (B–D), statistics were analysed by one-way ANOVA with multiple comparisons as indicated. In g , a two-sided unpaired Student’s t test was used. In (J) and (L), EM versus S1 was compared within each group by two-sided paired tests and preference indices were compared between groups by two-sided unpaired tests, as indicated. * P < 0.05, ** P < 0.01, *** P < 0.001; N.S., not significant.

Article Snippet: Valine (Sigma-Aldrich, cat. no. V0513), leucine (Sigma-Aldrich, cat. no. L8912), isoleucine (Sigma-Aldrich, cat. no. I2752), CHPG (MedChemExpress, cat. no. HY-101364), MPEP (MedChemExpress, cat. no. HY-14609A), MCPG (MedChemExpress, cat. no. HY-100371), AEA (MedChemExpress, cat. no. HY-10863) and the corresponding vehicle solutions were infused 30 min before behavioral testing unless otherwise indicated in the relevant figure legends.

Techniques: Activation Assay, Luciferase, Expressing, Concentration Assay, Control, Patch Clamp