Expression of PACAP Receptors in the Frog Brain during Development

: This study describes the expression of PAC1 and VPAC1 receptor (PAC1‐R and VPAC1‐R) mRNAs in the brain of frog (Rana esculenta) during development. PAC1‐R mRNA was detected in the periventricular and subependymal layers of the thalamus and epithalamus and in the ependymal layer of the mesencephalon and rhombencephalon (stage 20), in the amygdala, in the habenular complex, in the periventricular nucleus of the hypothalamus, and in the ventral cerebellum (stage 30). VPAC1‐R mRNA expression was observed only at stage 20, in the floor of the hypothalamus. These results suggest that, in amphibians, pituitary adenylate cyclase‐activating polypeptide (PACAP) may play a role in brain development.