Effects of PACAP in UV-A Radiation-Induced Retinal Degeneration Models in Rats

Abstract

The retina is constantly exposed to ultraviolet (UV) light with different wavelengths, which may lead to chronic UV-induced retinal injury. In our previous studies, we have shown the protective effects of pituitary adenylate cyclase activating polypeptide (PACAP) in toxic and ischemic retinal injuries. The aim of the present study was to investigate the effects of PACAP in UV-A-induced retinal lesion. We used diffuse UV-A radiation (315-400 nm) to induce acute retinal damage over a short period of exposure. Using standard histological (morphological and morphometrical) analysis, we assessed the actions of intravitreal PACAP (100 pmol/5 µl) treatment on acute UV-A-induced retinal damage. We measured the thickness of nuclear and plexiform layers as well as the number of cells in the outer nuclear and inner nuclear layers and in the ganglion cell layer. Outer limiting membrane-inner limiting membrane distances in the cross-section of the retina were also examined. Our results show that UV-A light-induced retinal damage led to severe degeneration in the photoreceptor layer, and in the outer and inner nuclear layers. Alteration in the plexiform layers was also observed. We found that post-irradiation PACAP treatment significantly attenuated the UV-A-induced retinal damage. Our results provide the basis for future clinical application of PACAP treatment in retinal degeneration and may have clinical implications in several ophthalmic diseases.

Protective Effects of PACAP in the Retina

“…In addition, severe degeneration in the ONL and INL was seen, and the IPL was swollen. PACAP1-38 treatment after the UV-A irradiation signifi cantly ameliorated the light-induced degeneration, the ONL and INL thickness seemed to be normal, and the number of cells in INL, ONL, and GCL was signifi cantly increased [ 89 ]. In a model of focused UV-A irradiation, the shape of the laser focus was observed on the retina, tissue gaps were found in the ONL and in the photoreceptor layer, and the IPL was reduced.…”

Passage through the Ocular Barriers and Beneficial Effects in Retinal Ischemia of Topical Application of PACAP1-38 in Rodents

“…In vitro, the peptide has been shown to protect whole retinal tissue cultures [20] and cell cultures from various cell types, including pigment epithelial cells [21,22] and retinal ganglion cells [23]. In vivo, PACAP is protective against NMDA-, glutamate- and kainate-induced retinal excitotoxicity [24,25,26], optic nerve transection [27], UV-induced retinal damage [28], diabetic retinopathy [29,30], retinopathy of prematurity [31] and ischemia-induced injury [32,33,34]. …”

Investigation of PACAP Fragments and Related Peptides in Chronic Retinal Hypoperfusion

“…In vitro, it protects retinal explants against excitotoxic injury [11] and retinal pigment epithelial cells against oxidative stress [12]. In vivo retina studies show that PACAP protects against NMDA- and MSG-induced excitotoxic damage [13, 14], UV light-induced lesion [15], and optic nerve lesion [16]. Recent studies show that PACAP is also protective in diabetic retinopathy [17].…”