[NMDAR expression in the cochlear nucleus and hearing damage in neonatal rats with hyperbilirubinemia].
OBJECTIVE
To study the role of N-methyl-D-aspartate-receptor (NMDAR) expression in the development of hearing damage in neonatal rats with hyperbilirubinemia.


METHODS
Sixty seven-day-old Sprague-Dawley rats were randomly injected with bilirubin of 100 microg/g (low-dose treatment group) or 200 microg/g (high-dose treatment group) or normal saline (control group). Auditory brainstem response (ABR) was examined. The concentrations of bilirubin in blood and brain were measured. NMDAR expression in the cochlear nucleus slices was examined by immunohistochemistry assay.


RESULTS
ABR reflecting threshold obviously increased, and I, II and III wave latency as well as I-II, II-III and I-III interval were more prolonged in the two bilirubin treatment groups when compared with the control group. The NMDAR expression in the cochlear nucleuse in the two bilirubin treatment groups was obviously lower than that in the control group. The NMDAR expression in the cochlear nucleuse was negatively correlated with the brain bilirubin content and the ABR reflecting threshold in the two bilirubin treatment groups.


CONCLUSIONS
An increased NMDAR activity may play an important role in hearing damage following hyperbilirubinemia.
Li
Ke-Fang
KF
Department of Otolaryngology, Third Affiliated Hospital, Zhengzhou University, Zhengzhou 450052, China.
Du
Kai-Xian
KX
Jiang
Yue-Xing
YX
Dong
Xue-Lei
XL
Zhang
Yan
Y
D000818:Animals; D000831:Animals, Newborn; D001663:Bilirubin / Q000032:analysis; D017626:Cochlear Nucleus / Q000737:chemistry*; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D006311:Hearing Disorders / Q000209:etiology*; D006932:Hyperbilirubinemia / Q000150:complications / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000032:analysis*
D016194:Receptors, N-Methyl-D-Aspartate; D001663:Bilirubin