STUDY OF THE PORCINE ELECTRORETINOGRAM AS PRECLINICAL MODEL FOR THE TREATMENT OF THE HUMAN RETINA HEREDITARY DEGENERATIONS

The present work has the aim to analyze, for the first time, the physiological activity of the pig’s retina using a standardized human electoretinogram protocol approved by the International Society for Clinical Electrophysiology of Vision (ISCEV). The experiment was conducted at the Livestock and Animal Testing unit of the Physiology service of the Department of Veterinary Medical Sciences of the University of Bologna, in accordance with the national and international guidelines on animal experimentation. All procedures were examined by the Ethics Committee of the University of Bologna, authorized in derogate by the Ministry of Health and controlled by the Central Veterinary Service of the University of Bologna during the implementation phase. The subjects are 30 healthy females piglets of 3 months old and weighing 30 kg. The pre medication is performed using Azaperone (2mg/kg of Stresnil) by intramuscular injection behind the ear. Then, the Ketamine (20mg/Kg of Ketavet), Medetomidine (0,04mg/kg of Medetor) and Atropine (0.04 mg/kg of Atropine sulfate) mixture is injected intramuscularly. The subject is left alone until the loss of the righting reflex. Two drops of mydriatic (Tropicamide 1%) per eye are instilled to obtain the necessary paralysis of the pupil. The instrument used for the retinal exam, is a Ganzfeld Stimulator Model GS-MAX for use in humans. The electrical signal data is recorded, amplified and analyzed by the program EREV2000 previously set for ERG sessions running in series. The electrodes are ERG-jet metal conductor model to transfer the bioelectric signal to the amplifier and they are divided in: subcutaneous or inox needle and corneals. Four different light stimulations are sent in order to record the photoreceptors response and to compare the average amplitudes for each protocol with the human and mouse data present in literature. This study confirm that a high cone density and the particular pig’s photoreceptor topography allow this animal to be the better choice for experimental modelling of human cone diseases than mouse. Additionally, this wide data background is a good resource for researchers involved in ophthalmic studies to choose the correct animal model for their experiment and to use the smallest possible number of animals needed to obtain a scientifically valid result.