Fig. 4: The D-AVA circuit suppresses avoidance response to noxious hyperosmolarity.

a Diagram depicting a simplified neural circuit for hyperosmolarity avoidance. b Application of a hyperosmotic glycerol solution but not the bath solution (control) caused inward current in AVA (held at −60 mV) and depolarization of AVA. Compared with control, p = 0.006 charge transfer, and 0.000 depolarization. c Knockdown of lgc-46 in GABAergic neurons greatly abated glycerol-induced inward current in VD5 and depolarization of VD5 compared with wild type (wt). Compared with wt, p = 0.012 charge transfer, and 0.014 depolarization. d, e Knockdown of either unc-49 in AVA or lgc-46 in GABAergic neurons augmented glycerol-induced AVA depolarization (d), and reduced escape probability from a hyperosmotic glycerol barrier (e). In d, compared with wt, p = 0.046 unc-49 RNAi, and 0.047 lgc-46 RNAi. In e, 10–15 worms were placed inside a glycerol ring (diameter about 1 cm), and the percentage of worms escaped in 15 min was quantified. The effect of only one concentration of glycerol was tested in each experiment. In b–d, glycerol solution (2 M) was applied to the vicinity of the nose through a puffing pipette. The asterisks indicate significant differences (*p < 0.05, **p < 0.01, ***p < 0.001) compared with either the control or wild type (wt) based on unpaired two-sided t-test (b, c), or one-way ANOVA with Tukey’s post hoc (d, e). The numbers inside brackets indicate sample size (n). n = numbers of independently recorded cells in b–d, but numbers of individual worms in e. In e, sample sizes of the wt and unc-49 RNAi groups varied among different glycerol concentrations. For wt, n = 13, 15, 16, 21, 16, and 16 for the concentrations of 0–4 M. For unc-49 RNAi, n = 16, 20, 12, 12, 12, and 20 for the concentrations of 0–4 M. Data are presented as mean values ± SEM. Source data are provided as a Source data file.