Sympathetic Effects of Internal Carotid Nerve Manipulation on Choroidal Vascularity and Related Measures
Abstract
Purpose: To investigate specific effects of denervation and stimulation of the internal carotid nerve (ICN) on the choroid and retina. Methods: Female Sprague Dawley rats underwent unilateral ICN transection (n = 20) or acute ICN electrical stimulation (n = 7). Rats in the denervation group were euthanized 6 weeks after nerve transection, and eyes were analyzed for changes in choroidal vascularity (via histomorphometry) or angiogenic growth factors and inflammatory markers (via ELISA). Rats in the stimulation group received acute ICN electrical stimulation with a bipolar cuff electrode over a range of stimulus amplitudes, frequencies, and pulse widths. Choroidal blood flow and pupil diameter were monitored before, during, and after stimulation. Results: Six weeks after unilateral ICN transection, sympathectomized choroids exhibited increased vascularity, defined as the percentage of choroidal surface area occupied by blood vessel lumina. Vascular endothelial growth factor (VEGF) and VEGF receptor-2 (VEGFR-2) protein levels in denervated choroids were 61% and 124% higher than in contralateral choroids, respectively. TNF-α levels in denervated retinas increased by 3.3-fold relative to levels in contralateral retinas. In animals undergoing acute ICN electrical stimulation, mydriasis and reduced choroidal blood flow were observed in the ipsilateral eye. The magnitude of the reduction in blood flow correlated positively with stimulus frequency. Conclusions: Modulation of ICN activity reveals a potential role of the ocular sympathetic system in regulating endpoints related to neovascular diseases of the eye.
Additional Information
© 2019 The Authors. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. The authors thank Danhong Zhu for her help with the ELISA assays. Supported by a grant from Galvani Bioelectronics to ACW, MSH, and DRH, as well as unrestricted departmental support to the USC Roski Eye Institute from Research to Prevent Blindness. Disclosure: J.-C. Martinez-Camarillo, None; C.K. Spee, None; M. Chen, None; A. Rodriguez, None; K. Nimmagadda, None; G.P. Trujillo-Sanchez, None; D.R. Hinton, Galvani Bioelectronics (F); A. Giarola, P; V. Pikov, P; A. Sridhar, E, P; M.S. Humayun, Galvani Bioelectronics (F), P; A.C. Weitz, Galvani Bioelectronics (F), PAttached Files
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Additional details
- Eprint ID
- 99387
- Resolver ID
- CaltechAUTHORS:20191022-104814157
- Galvani Bioelectronics
- University of Southern California
- Created
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2019-10-22Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field