Figure 7.

Quantitative ISH analyses of HCN4 mRNA expression in developing hippocampus. (A) HCN4 mRNA is robustly expressed in neonatal CA1 pyramidal cell layer, where it decreases progressively with age (P2–P90: ~65%). In contrast, HCN4 mRNA expression is low in CA3 pyramidal cell layer and DG granule cell layer (GCL) on P2. With maturation expression increases 2-fold in CA3, whereas it remains constant in GCL. Note that HCN4 mRNA levels are lower than those of HCN1 (Fig. 1) and HCN2 (Fig. 4) and are shown on an expanded scale. (B) Representative autoradiographs show hippocampal HCN4 mRNA signal on P2, P11, P18, and P90 and the results of control ISH experiments using sense probe or excess (100×) unlabeled antisense probe in addition to labeled probe.