Figure 6.

Downstream Signaling of GRPRs

(A) Effects of XE-991 (10 μM, ≥6 min, light-blue bar, n = 5 from 3 mice), ML365 (10 μM, ≥ 6 min, blue bar, n = 5 from 4 mice), and Ba²⁺ (200 μM, ≥ 6 min, green bar, n = 6 from 3 mice) on the RMP of GRPR_excit neurons and on GRP-mediated depolarization (300 nM). Repeated-measurements one-way ANOVA, followed by Bonferroni post hoc tests, F(2,8) = 47.2 (XE-991), 14.4 (ML365), F(2,10) = 49.4 (Ba²⁺). p < 0.0001 (XE-991), p = 0.022 (ML365), p < 0.0001 (Ba²⁺). Right: changes in R_i induced by Ba²⁺ (200 μM) and GRP (300 nM). Repeated-measurements one-way ANOVA, followed by Bonferroni post hoc tests, F(2,17) = 12.7, p = 0.0018.

(B and C) Depolarization by 7 mV of the RMP changed delayed firing into tonic-like firing (B) and increased action potentials probability in response to somatic EPSC-like current injections (C). Left: voltage trace examples evoked by EPSC-like current injections of increasing amplitude (50–400 pA). Right: stimulus response curves (n = 11 from 3 mice) fitted to the Boltzmann equation.

(D) A 7 mV depolarization of the RMP reduced A-type potassium current amplitudes in GRPR_excit neurons by 61.9% ± 5.3% (n = 11, p < 0.0001, two-tailed, paired t test).

(E) GRP (300 nM) had no effects on the A-type potassium current amplitude when the membrane potential was kept constant (7.0% ± 3.5%, n = 8 from 3 mice; p = 0.11; two-tailed, paired t test).

(F) Schematic illustration of the intracellular signaling events triggered by GRPR activation in GRPR_excit neurons.