Figure 3.

A) Expression analysis of 5-HT₄ receptor transcripts in embryonic and post-natal mouse tissues. RT-PCR analysis was performed with RNA extracted from various mouse tissues (the brain (B), the eye (E), the heart (H), and the trunk (T). The 12^th, 16^th, 20^th GD and 1 DPN are represented in lane 1–2, 3–5, 6–8 and 9–11 respectively. The PCR products were analysed on a 1.5% agarose gel and photographs of the ethidium bromide stained gels are shown (upper panel). The PCR primers used for this analysis and expected length of the PCR products are described in Materials and Methods. A positive control was performed with β-actin primers on mRNA samples treated with reverse transcriptase. This figure is representative of three separate determinations of mouse 5-HT₄ receptor mRNA expression obtained by RT-PCR. The specificity of the PCR products were analysed by Southern blotting using a ³²P-5'-end-labeled internal primer (lower panel). A 3 h exposure of the autoradiogram is shown. Positions of the molecular weight markers are indicated in bp. m5-HT₄R, mouse 5-HT₄ receptor; Marker, molecular weight marker. 3B-D) Normal receptor expression at protein level detected using anti-5-HT_4(a) and anti-5-HT_4(d) antibodies in heart (B) atrium (a) myocardium (M) ventricle (V) brain, (C) in cortex (c) hippocampus (CA₁) frontal cortex (FC), during different embryonic periods and at birth. Figure 3D shows the normal expression of 5-HT₄ receptor in hippocampus of adult BALB/c mouse. Immunolabelling is shown in the left panel and DAPI nuclear coloration in the right one.