Environmental Enrichment Protects the Retina from Early Diabetic Damage in Adult Rats

Abstract

Diabetic retinopathy is a leading cause of reduced visual acuity and acquired blindness. Available treatments are not completely effective. We analyzed the effect of environmental enrichment on retinal damage induced by experimental diabetes in adult Wistar rats. Diabetes was induced by an intraperitoneal injection of streptozotocin. Three days after vehicle or streptozotocin injection, animals were housed in enriched environment or remained in a standard environment. Retinal function (electroretinogram, and oscillatory potentials), retinal morphology, blood-retinal barrier integrity, synaptophysin, astrocyte and Müller cell glial fibrillary acidic protein, vascular endothelial growth factor, tumor necrosis factor-α, and brain-derived neurotrophic factor levels, as well as lipid peroxidation were assessed in retina from diabetic animals housed in standard or enriched environment. Environmental enrichment preserved scotopic electroretinogram a-wave, b-wave and oscillatory potential amplitude, avoided albumin-Evan's blue leakage, prevented the decrease in retinal synaptophysin and astrocyte glial fibrillary acidic protein levels, the increase in Müller cell glial fibrillary acidic protein, vascular endothelial growth factor and tumor necrosis factor-α levels, as well as oxidative stress induced by diabetes. In addition, enriched environment prevented the decrease in retinal brain-derived neurotrophic factor levels induced by experimental diabetes. When environmental enrichment started 7 weeks after diabetes onset, retinal function was significantly preserved. These results indicate that enriched environment could attenuate the early diabetic damage in the retina from adult rats.

Study of retinal neurodegeneration and maculopathy in diabetic Meriones shawi: A particular animal model with human‐like macula

“…Similar patchy distribution was also noticed with the vimentin labeling of M€ uller cells in M.sh, but unlike with GFAP, showing a decrease of reactivity in diabetic retinas. Vimentin downregulation was also detectable in the report of Enzsoly et al (2015) in T1D diabetic rats, while in another report from the same model (Dorfman et al, 2014) and also in T2D ZDF rats (Zucker Diabetic Fatty rats) (Szab o et al, submitted) no change in vimentin-staining was reported.…”

Enriched Environment Protects the Optic Nerve from Early Diabetes-Induced Damage in Adult Rats

“…The exposure to EE is known to produce functional recovery after various types of CNS lesions [ 4 , 29 , 30 ]. We have previously shown that EE housing protects the adult retina against acute ischemic [ 12 ], and early diabetic [ 27 ] damage. However, the beneficial effect of EE housing against ON alterations induced by chronic damage such as STZ-induced experimental diabetes was not previously examined.…”

“…For the control group (standard environment, (SE)), animals (2 per cage) were housed in standard laboratory cages (33.5 x 45 x 21.5 cm). For enriched environment (EE) housing, six animals at a time were housed in big metallic cages (46.5 x 78 x 95 cm), containing four floors and several food hoppers, water bottles, running wheels, tubes, ramps and differently shaped objects (balls, ropes, stones) daily repositioned, and fully substituted once a week, as previously described [ 27 ]. Particular care was taken not to repeat cage arrangement and object availability during the experiments.…”

“…Since at this time point (i.e., at 6 weeks after STZ injection), no substantial structural alterations are evident in the retina, or the main retinal synaptic target in rodents, the superior colliculus (SC), these results suggest that axoglial alterations at the distal (close to the chiasm) portion of the ON could be the first structural change in the diabetic visual pathway [ 26 ]. Recently, we have demonstrated that EE housing prevents the electroretinographic dysfunction, and preserves inner retina synapses, and blood retinal barrier integrity at early stages of experimental diabetes induced by STZ in adult rats [ 27 ]. Having demonstrated significant neurodegenerative changes in the distal portion of the ON, and a protective effect of EE on retinal injury at early stages of experimental diabetes, the aim of the present report was to explore whether EE is able to protect the ON from axoglial alterations induced by experimental diabetes.…”

Neurogênese e plasticidade sináptica no Hipocampo de ratos submetidos à separação materna e enriquecimento ambiental

“…von Bhlen e Halbach, 2007). Tampouco foram observadas células doublecortina positivas colocalizadas com células positivas para TUNEL, marcador de células em apoptose (Rao e Shetty, 2004 (Dorfman et al, 2014).…”