Chronic intraocular pressure elevation impairs autoregulatory capacity in streptozotocin-induced diabetic rat retina


Autoria(s): Wong, Vickie H.; Armitage, James A.; He, Zheng; Hui, Flora; Vingrys, Algis J.; Bui, Bang V.
Data(s)

01/03/2015

Resumo

Purpose: To assess ocular blood flow responses to acute IOP stress following 4 weeks of chronic IOP elevation in streptozotocin (STZ)-induced diabetic and control rats. We hypothesise that chronic IOP elevation for 4 weeks will further impair blood flow regulation in STZ-induced diabetic rats eyes. Methods: Two weeks following citrate buffer or STZ-injections chronic IOP elevation was induced in Long Evans rats via fortnightly intracameral injections of microspheres (15 μm) suspended in 5% polyethylene glycol. IOP was monitored daily. Electroretinography (ERG, -6.79-2.07 log cd s m-2) was undertaken at Week 4 to compare photoreceptor (RmPIII), ON-bipolar cell (Vmax) and ganglion cell dominant ERG [scotopic threshold response (STR)] components. 4 weeks post-chronic IOP induction, ocular blood flow (laser Doppler flowmetry) was measured in response to acute IOP challenge (10-100 mmHg, in 5 mmHg steps, each 3 min). Results: Four weeks of chronic IOP (mean ± S.E.M., citrate: 24.0 ± 0.3 to 30.7 ± 1.3 and STZ-diabetes: 24.2 ± 0.2 to 31.1 ± 1.2 mmHg) was associated with reduced photoreceptor amplitude in both groups (-25.3 ± 2.2% and -17.2 ± 3.0%, respectively). STZ-diabetic eyes showed reduced photoreceptor sensitivity (citrate: 0.5 ± 1.8%, STZ-diabetic: -8.1 ± 2.4%). Paradoxically ON-bipolar cell sensitivity was increased, particularly in citrate control eyes (citrate: 166.8 ± 25.9%, STZ-diabetic: 64.8 ± 18.7%). The ganglion cell dominant STR was not significantly reduced in STZ-diabetic rats. Using acute IOP elevation to probe autoregulation, we show that STZ-diabetes impaired autoregulation compared with citrate control animals. The combination of STZ-diabetes and chronic IOP elevation further impaired autoregulation. Conclusions: STZ-diabetes and chronic IOP elevation appear to be additive risk factors for impairment of ocular blood flow autoregulation.

Identificador

http://hdl.handle.net/10536/DRO/DU:30072194

Idioma(s)

eng

Publicador

Wiley

Relação

GNT 1046203

http://dro.deakin.edu.au/eserv/DU:30072194/wong-chronicintraocular-2015.pdf

http://www.dx.doi.org/10.1111/opo.12174

Direitos

2015, Wiley

Palavras-Chave #Blood flow #Diabetes #Electroretinogram #Intraocular pressure #Rat #Retina
Tipo

Journal Article