Aims: 

Pituitary adenylate cyclase activating polypeptide (PACAP) is a neurotrophic and neuroprotective peptide. PACAP and its receptors are present in the retina. We have provided evidence that PACAP is neuroprotective in retinal degenerations. In this study we asked if certain neurons of rat retina have specific PACAP receptor (PAC1-R) and whether cell type-specific differences exist between the retinas of wild type and PACAP deficient mice.

Methods: 

Rats, wild type and PACAP KO mice retinas were processed for immunohistochemistry for tyrosine hydroxylase, calretinin, calbindin, parvalbumin, PKCa and PAC1-R.

Results: 

No significant differences were observed by standard histological methods between the retinas of wild type and PACAP deficient mice. For the characterization of the different cell types we used immunohistochemical markers. Only a few parvalbumin- and calretinin-containing cells expressed PAC1-R. We could not detect PAC1-R localization in dopaminergic amacrine, bipolar and horizontal cells. The staining of PACAP KO retinas was similar to that of wild type retinas, with no significant alterations in immunoreactivity patterns except for the PAC1-R staining. We observed that only few cells expressed PAC1-R in PACAP KO compared to wild type retinas.

Conclusion: 

We conclude that the results of the histological examinations are supported by the fact that no immunohistological differences could be found between the wild type and PACAP deficient mice using retina-specific markers. Further investigations are needed to identify all PAC1-R containing retinal neurons.

Support: 

OTKA; CNK; ETT; Richter; Science, Please!; SROP