Susceptibility of streptozotocin-induced diabetic rat retinal function and ocular blood flow to acute intraocular pressure challenge.

Vickie H Y Wong, Algis J Vingrys, Andrew I Jobling, Bang V Bui

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Abstract

PURPOSE: To consider whether STZ-induced hyperglycemia renders rat retinal function and ocular blood flow more susceptible to acute intraocular pressure (IOP) challenge.

METHODS: Retinal function (electroretinogram, ERG) was measured during acute IOP challenge (10-100 mmHg, 5 mmHg increments, 3 min/step, vitreal cannulation) in adult Long-Evans rats (6-week old, citrate: n=6, STZ: n=10) 4 weeks after citrate buffer or streptozotocin (STZ, 65 mg/kg, blood glucose > 15 mmol/l) injection. At each IOP, dim and bright flash (-4.56, -1.72 log cd.s.m^-2) ERG responses were recorded to measure inner retinal and ON-bipolar cell function, respectively. Ocular blood flow (laser Doppler flowmetry, citrate; n=6, STZ; n=10) was also measured during acute IOP challenge. Retinae were isolated for qPCR analysis of nitric oxide synthase mRNA expression endothelial, eNos; inducible, iNos; neuronal, nNos).

RESULTS: STZ-induced diabetes increased the susceptibility of inner retinal (IOP at 50% response, 60.1, CI: 57.0-62.0 mmHg vs. citrate: 67.5, CI: 62.1-72.4 mmHg) and ON-bipolar cell function (STZ: 60.3, CI: 58.0-62.8 mmHg vs. citrate: 65.1, CI: 58.0-62.78 mmHg) and ocular blood flow (43.9, CI: 40.8-46.8 vs. citrate: 53.4, CI: 50.7-56.1 mmHg) to IOP challenge. Citrate eyes showed elevated eNos mRNA (+49.7%) after IOP stress, an effect not found in STZ-diabetic eyes (-5.7%, P<0.03). No difference was observed for iNos or nNos (P>0.05) following IOP elevation.

CONCLUSIONS: STZ-induced diabetes increased functional susceptibility during acute IOP challenge. This functional vulnerability is associated with a reduced capacity for diabetic eyes to upregulate eNOS expression and to autoregulate blood flow in response to stress.
Original languageEnglish
Pages (from-to)2133-2141
JournalInvestigative ophthalmology & visual science
Volume54
Issue number3
DOIs
Publication statusPublished - Mar 2013

Keywords

  • Animals
  • Antibiotics, Antineoplastic
  • Diabetes Mellitus, Experimental
  • Disease Models, Animal
  • Disease Susceptibility
  • Electroretinography
  • Eye
  • Intraocular Pressure
  • Nitric Oxide Synthase
  • Ocular Hypertension
  • Polymerase Chain Reaction
  • RNA, Messenger
  • Rats
  • Rats, Long-Evans
  • Retina
  • Streptozocin

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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