Fenotipado de modelos animales de degeneración retiniana y su aplicabilidad a la investigación oftalmológica

Abstract

Introduction: The creation and characterisation of new experimental animal models is a pressing need today. These models can be valid as a tool for the study of human diseases, as well as for the evaluation of new therapeutic agents. In the field of vision sciences, retinal degeneration models are one of the basic pillars of research, allowing the study of the physiopathological mechanisms of diseases which affect the visual system. Hypothesis and objectives: Is it possible to create animal models with different degrees of blindness who mimic the human’s eye diseases? Whether through genetic modifications or by inducing lesions that can evolve into degeneration, this work will characterise new animal models, testing their potential use as research tools for pathologies involving neurodegeneration of retinal cells. Likewise, new therapeutic molecules will be studied using these animal models. Methods: On the one hand, by backcrossing genetically manipulated experimental animals, a completely blind animal model (Opn4-/- x Rd10) has been generated. On the other hand, by intraocular injection of various excitotoxic agents (NMDA/KA) or chemicals with a potent oxidative effect (sodium iodate), a degenerative lesion in the retina has been induced, ranging from a subtle affectation to total blindness. The functional characterisation of these animal models has been carried out using different behavioural, electrophysiological and structural techniques. Once characterised, some of these models have been used to study molecules with pharmacological effects. Results: Using some behavioural techniques, it was possible to demonstrate the impairment of various visual functions in the different animal models. Their ability to detect illuminated spaces, visual acuity or even the pupillary reflex showed a huge dysfunction due to the course of the different neurodegenerative lesions. Electrophysiological tests corroborated the results obtained by the behavioural tests. Generally, decreases were observed in the amplitude of the waves recorded by flash electroretinogram, as well as a dysfunction in the ganglion cell layer recorded by pattern electroretinogram or even at the level of the primary visual cortex, by recording visual evoked potentials. Immunohistochemical labelling showed cell damage in the outer retinal layers in the mutant model (Opn4-/- x Rd10) and after administration of the oxidative stress agent (sodium iodate), while severe damage in the inner retinal layers was observed in the model induced by inoculation with excitotoxic agents (NMDA/KA). Finally, two new molecules with pharmacological capabilities were studied using the outer retinal degeneration models (Opn4-/- x Rd10 and sodium iodate), verifying their functional effect on these animals using several behavioural and electrophysiological tests. Conclusions: The results obtained by combining the entire battery of tests performed on each model, both genetic and chemical damaged, validate the animal models described as promising tools for the study of future therapeutic agents in retinal degenerative diseases.