Aims: 

Since its first discovery the pituitary adenylate cyclase activating polipeptide (PACAP) has been recognized as an ubiquitous and pleiotropic regulator in various multicellular organisms. Although the literature proving the presence of PACAP receptors (PAC-1, VPAC1, VPAC2) in central nervous system is vast, a precise analysis of their status in the time course of development is missing.

Methods: 

By using a comprehensive primer system, we performed quantitative analyses on the expression of PACAP receptors and splice variants during the postnatal development of the rat retina. Tissues were harvested in postnatal days P0 (newborn), P1, P3, P5, P10, P15 and P20. Receptor expression differences at the transcript level were selectively detected by quantitative real-time PCRs.

Results: 

VPAC1 and VPAC2 displayed a biphasic expression patterns during postnatal development with outstanding peaks at P5 and P15. Interestingly, the results showed no overall changes in PAC-1 message level when splice-independent standard primers were used. However, using splicing variant specific primers, the analysis revealed that the Short, HIP, HOP1, HIPHOP1 variants were expressed in the rat retina and each showed a unique expression profile. The transcript levels of the Short and HIP splice variants showed a gradual decline while expression of HOP1 variant increased significantly during development. HIPHOP1 transcript did not display significant changes except at P10 with a transient 9-fold increase.

Conclusion: 

We can conclude that a certain set of PACAP receptors are present in rat retina and their temporal change might be critical to coordinate the postnatal retinal development.