Neuropeptide Y treatment induces retinal vasoconstriction and causes functional and histological retinal damage in a porcine ischaemia model

TY - JOUR

T1 - Neuropeptide Y treatment induces retinal vasoconstriction and causes functional and histological retinal damage in a porcine ischaemia model

AU - Christiansen, Anders T.

AU - Sørensen, Nina B.

AU - Haanes, Kristian A.

AU - Blixt, Frank W.

AU - la Cour, Morten

AU - Warfvinge, Karin

AU - Klemp, Kristian

AU - Woldbye, David P.D.

AU - Kiilgaard, Jens F.

PY - 2018/12

Y1 - 2018/12

N2 - 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.

AB - 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.

KW - multifocal electroretinogram

KW - neuropeptide Y

KW - neuropeptide Y receptors

KW - neuroprotection

KW - retina

KW - swine

KW - vasoconstriction

U2 - 10.1111/aos.13806

DO - 10.1111/aos.13806

M3 - Journal article

C2 - 30218483

AN - SCOPUS:85053448239

SN - 1755-375X

VL - 96

SP - 812

EP - 820

JO - Acta Ophthalmologica

JF - Acta Ophthalmologica

IS - 8

ER -