Premium
Neuropeptide Y treatment induces retinal vasoconstriction and causes functional and histological retinal damage in a porcine ischaemia model
Author(s) -
Christiansen Anders T.,
Sørensen Nina B.,
Haanes Kristian A.,
Blixt Frank W.,
Cour Morten,
Warfvinge Karin,
Klemp Kristian,
Woldbye David P. D.,
Kiilgaard Jens F.
Publication year - 2018
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/aos.13806
Subject(s) - neuropeptide y receptor , retinal , vasoconstriction , medicine , retina , constriction , ischemia , endocrinology , anatomy , ophthalmology , receptor , biology , neuropeptide , neuroscience
Purpose To investigate the effects of intravitreal neuropeptide Y (NPY) treatment following acute retinal ischaemia in an in vivo porcine model. In addition, we evaluated the vasoconstrictive potential of NPY on porcine retinal arteries ex vivo . Methods Twelve pigs underwent induced retinal ischaemia by elevated intraocular pressure clamping the ocular perfusion pressure at 5 mmHg for 2 hr followed by intravitreal injection of NPY or vehicle. After 4 weeks, retinas were evaluated functionally by standard and global‐flash multifocal electroretinogram (mfERG) and histologically by thickness of retinal layers and number of ganglion cells. Additionally, the vasoconstrictive effects of NPY and its involved receptors were tested using wire myographs and NPY receptor antagonists on porcine retinal arteries. Results Intravitreal injection of NPY after induced ischaemia caused a significant reduction in the mean induced component (IC) amplitude ratio (treated/normal eye) compared to vehicle‐treated eyes. This reduction was accompanied by histological damage, where NPY treatment reduced the mean thickness of inner retinal layers and number of ganglion cells. In retinal arteries, NPY‐induced vasoconstriction to a plateau of approximately 65% of potassium‐induced constriction. This effect appeared to be mediated via Y1 and Y2, but not Y5. Conclusion In seeming contrast to previous in vitro studies, intravitreal NPY treatment caused functional and histological damage compared to vehicle after a retinal ischaemic insult. Furthermore, we showed for the first time that NPY induces Y1‐ and Y2‐ but not Y5‐mediated vasoconstriction in retinal arteries. This constriction could explain the worsening in vivo effect induced by NPY treatment following an ischaemic insult and suggests that future studies on exploring the neuroprotective effects of NPY might focus on other receptors than Y1 and Y2.