Hiperbilirubinemili Yenidoğan Wistar Albino Rat Modelinde Elektrofizyolojik İşitsel Yanıtların Morfolojik Bulgularla Karşılaştırılması

Abstract

Hyperbillirubinemia is a common health problem of newborns. It’s effects can be different according to level of hiperbillirubinemi which can be a result of a failure in a certain pathway of the billirubin methabolism and duration of the hiperbillirubinemia. The toxic effect of billirubin on auditory system can be seen as sensoryneural hearing loss (SNHL) and auditory neuropathy spectrum disorders (ANSD). The animal models used for more better understanding the effect of hipperbillirubinemia on hearing system and for morphologic assesment at the same time rats are preferred for the reasons of low cost and easy attainability. Auditory Brainstem Response (ABR) and Otoacustic Emissions (OAE) are used for auditory asessment. This study has been made on Hacettepe University Institute of Health Sciences Audiology and Speech Disorders program expertise as a thesis of physical doctora. Three groups has been made for this study as experiment group, control group and placebo group. Totally 18 rats used as 6 in every group. Morphometric evaluation and electrophysiologic tests for the asessment of hearing have been made for every rat. The effect of hiperbillirubinemia on auditory system were evaluated by electrophysiologic test methods and morphological by comparing the results of tests. In the experiment group that consists rats with hiperbillirubinemia the ABR tresholds of left ear found high which is statistically significant(p<0.05). In the experiment group SNHL found bilaterally in 4 rats(%66,67), unilaterally in 2 rats(%16,67) and ANSD found unilaterally in 1 rat (%8,33). Morphologic evaluation has been made by light microscope and outer hair cells (OHC) and iner hair cells (IHC) have been evaluated in cochlear cross-section and cochler nucleuses (CN) have been evaluated in brainstem cross-sections. All cross-sections of rats couldn’t have been evaluated due to problem in fixation. Deformation in the character of apoptosis and decrease in the account of cell was observed in the structure of inner and outer hair cells of groups that takes placebo solution and rats with hyperbilluribinemia in histologic evaluation. As a result the hiperbillirubinemia of the newborn may result SNHL and ANSD.