Abstract
BackgroundImpairment of neurovascular coupling (NVC) was recently reported in the context of subarachnoid hemorrhage and may correlate with disease severity and outcome. However, previous techniques to evaluate NVC required invasive procedures. Retinal vessels may represent an alternative option for non-invasive assessment of NVC.MethodsA prototype of an adapted retinal vessel analyzer was used to assess retinal vessel diameter in mice. Dynamic vessel analysis (DVA) included an application of monochromatic flicker light impulses in predefined frequencies for evaluating NVC. All retinae were harvested after DVA and electroretinograms were performed.ResultsA total of 104 retinal scans were conducted in 21 male mice (90 scans). Quantitative arterial recordings were feasible only in a minority of animals, showing an emphasized reaction to flicker light impulses (8 mice; 14 scans). A characteristic venous response to flicker light, however, could observed in the majority of animals. Repeated measurements resulted in a significant decrease of baseline venous diameter (7 mice; 7 scans, p < 0.05). Ex-vivo electroretinograms, performed after in-vivo DVA, demonstrated a significant reduction of transretinal signaling in animals with repeated DVA (n = 6, p < 0.001).ConclusionsTo the best of our knowledge, this is the first non-invasive study assessing murine retinal vessel response to flicker light with characteristic changes in NVC. The imaging system can be used for basic research and enables the investigation of retinal vessel dimension and function in control mice and genetically modified animals.
Highlights
Neurovascular coupling (NVC) enables a transient increase in neural activity by increasing cerebral blood flow and metabolism [1]
A total of 104 retinal scans were conducted in 21 male mice (90 scans)
Neurovascular coupling in murine retina role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript
Summary
Neurovascular coupling (NVC) enables a transient increase in neural activity by increasing cerebral blood flow and metabolism [1]. In response to transient neural activity, nearby vessels dilate, vessel resistance is reduced and blood flow increases [2]. The retina as an embryological part of the central nervous system may be suitable to study neurovascular principles of the brain by investigating retinal reactivity to locally enhanced neuronal activity non-invasively (“retina as a window to the brain”). As a possible clinical analogue, altered autoregulation in the brain was observed after aneurysmal subarachnoid hemorrhage (SAH) contributing to disturbances of cerebral blood flow and resulting in poor clinical outcome [11,12,13]. Impairment of neurovascular coupling (NVC) was recently reported in the context of subarachnoid hemorrhage and may correlate with disease severity and outcome. Retinal vessels may represent an alternative option for non-invasive assessment of NVC
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