Fig. 7: Altered signaling in ASIC1a^−/− mice at the level of the hypothalamus and pituitary, but not the thyroid.

a, c, f, g mRNA levels quantified by RT-qPCR. b, d, e activity or quantity of proteins. In the RT-qPCR experiments, the gene expression levels were normalized to the mean expression of a given gene in WT at ZT1. a Tshb mRNA levels in pituitary pars distalis (PD); n = 4–5 animals per condition. b Activity of TSH in PD at the indicated time points, expressed as mU TSH/g of protein, n = 6–9 animals per condition. c Prl mRNA levels in the PD of the pituitary, n = 4–5 animals per condition. d Activity of TSH, T3 and T4 in serum at the indicated time points; n = 5–9 animals per condition. e Activity of TSH in pituitary pars tuberalis (PT) at the indicated time points, expressed as mU TSH/g protein; n = 6–9 animals per condition. f RT-qPCR analysis of Tshb expression in mouse PT; n = 6–7 animals per condition. g mRNA levels of Dio2 and Dio3 in MBH, n = 6–9 animals per condition. **p < 0.01; ****, p < 0.0001; WT compared to ASIC1a^−/− at the corresponding ZT; ^#p < 0.05; ^###p < 0.001; ^####p < 0.0001; comparison for a given genotype between the ZT conditions; two-way ANOVA test and Holm-Sidak’s post hoc test. In d, the 2-way ANOVA analysis indicated that the genotype did not add to the variation, while the ZT did (p < 0.05 for TSH, and p < 0.0001 for T3 and T4). Statistical analysis was done on log2-transformed data, except for d where absolute values were used. Error bars indicate SEM. h Diagram summarizing the conclusions of the current work (created with BioRender). Left zoom, postsynaptic ASIC1a channels are activated by a drop in the pH in the synaptic cleft in PVH under dark conditions, leading to Ca²⁺ influx. The increase in intracellular Ca²⁺ activates the downstream PI3K/Akt/mTOR/CREB signaling pathway. p-CREB regulates the expression of Trh and Prl. Center and right, Neuronal signaling in the SCN and PVH controls TRH release. TRH stimulates the release of TSH from pituitary PD. Increased TSH in the PT increases the expression of DIO2, which promotes the secretion of T3 from the MBH to inhibit the expression of Trh in the PVH. Hypothalamic PRL inhibits PRL secretion in the pituitary. The changes in voluntary activity and body temperature may also depend on PRL. In the ASIC1a^−/− mice, the serum TSH, T3, and T4 activities were not changed. ASIC1a presumably regulates the body temperature by other changes in the hypothalamus, which include changed activity, food intake, and/or metabolism.