PACAP and NAP: Effect of Two Functionally Related Peptides in Diabetic Retinopathy.

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a peptide involved in physio-pathological processes of the eye. It exerts multiple effects directly through activation of its related receptors and indirectly through increases in the synthesis of activity-dependent neuroprotective protein (ADNP). To study the role of ADNP and protect against ADNP deficiencies, a small peptide called NAP was synthetized. It includes an eight amino acid active site sequence of ADNP. In this review, we summarize the knowledge regarding the neuroprotective function played by PACAP and NAP in retinal tissue and provide an overview of the correlation between PACAP and ADNP in the context of diabetic retinopathy.