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Lars Edvinsson, Frank W Blixt, Vadim Fedulov, Karin D Sörensen, Kristian A Haanes, Karin Warfvinge; WITHDRAWN - Similarities in expression of CGRP/PACAP and their receptors in the rat retina. Invest. Ophthalmol. Vis. Sci. 2018;59(9):5505.
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It has previously been shown that activation of the trigeminovascular system lead to the release of CGRP (calcitonin gene-related peptide) can be seen in migraine. In addition, clinical experiments have shown that PACAP (pituitary adenylate cyclase activating peptide) may elicit a migraine-like headache. Migraine with aura is associated with disturbances in the visual field. In addition, migraine attacks are often associated with photophobia. With these different visual phenomena experienced by migraine patients in mind, it is vital to understand the role of sensory neuropeptides CGRP/PACAP in various parts of the retina. Therefore, we aim at investigate the distribution and relations between CGRP/PACAP and their receptors in the rat retina.
Single and double immunohistochemistry were applied on frozen sections of adult rat retina using primary antibodies against CGRP, RAMP1, PACAP-38, PAC1, vimentin, synaptophysin.
The distribution pattern for the neuropeptides and their receptors correlated in the way that they were expressed in the most inner part of the retina, i.e. the ganglion cell layer and the nerve fiber layer. However, amacrine cells expressed CGRP but only some expressed PACAP. RAMP1 was only expressed in the nerve fiber layer. PAC1 immunoreactivity was found in the nerve fiber layer, ganglion cell layer and in the OPL. CGRP and RAMP1 did not co-express. PACAP and PAC1 sometimes co-expressed in the nerve fiber layer, but most often no double-labeling could be found.
It has recently been demonstrated that the nerve fiber layer is significantly thinner in migraineurs compared with healthy controls (Reggio et al 2017). We demonstrate in the present study that CGRP and PACAP, and their receptors, are concentrated to the nerve fiber layer. This could indicate that the peptides investigated, CGRP and PACAP, could play a central role in the visual phenomena experienced by migraineurs.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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