Pituitary adenylate cyclase-activating polypeptide (
PACAP), which is found in 27- or 38-amino
acid forms, belongs to the VIP/
glucagon/
secretin family.
PACAP and its three receptor subtypes are expressed in neural tissues, with
PACAP known to exert a protective effect against several types of neural damage. The retina is considered to be part of the central nervous system, and retinopathy is a common cause of profound and intractable loss of vision. This review will examine the expression and morphological distribution of
PACAP and its receptors in the retina, and will summarize the current state of knowledge regarding the protective effect of
PACAP against different kinds of
retinal damage, such as that identified in association with diabetes, ultraviolet light,
hypoxia,
optic nerve transection, and toxins. This article will also address
PACAP-mediated protective pathways involving
retinal glial cells.