All issues > Volume 44(4); 2001

Original Article

J Korean Pediatr Soc. 2001;44(4):433-442. Published online April 15, 2001.

Experssion of the NR2A and 2B Subunits of N-Methyl-D-aspartate Receptors in Hypoxic Neonatal Rat Hippocampus

Jong Su JS Lee¹, Dong Seok DS Lee², Jung hyun JH Park³, Il Soo IS Moon¹, Bok Hyun BH Ko¹, Yong Wook YW Jung¹

¹Departments of Anatomy, School of medicine, Dongguk University, Kyongju, korea
²Departments of Pediatrics, School of medicine, Dongguk University, Kyongju, korea
³Departments of Anatomy, School of medicine, Youngnam University, Taegu, korea

Correspondence Yong Wook YW Jung ,Email: kls117@dumc.or.kr

Abstract

Purpose
: The developing brain has been reported to be extremely susceptible to toxicity of ischemia and/or hypoxia during a restriced developmental period. Hippocampal neuronal cell death is a typical type of perinatal hypoxic brain lesion and often coexists with other forms of cerebral hypoxic injuries. In the present study, we examined whether transcriptional changes of NR2A and NR2B subunits of the N-Methyl-D-aspartate(NMDA) receptors related to the neuronal cell death to hypoxic toxicity are involved in developing neurons in hippocampus.
Methods
: We examined the lesion produced by in vivo direct exposure of 92% N2 and 8% O2 for 2 hours at postnatal day 7. Hippocampal sections from the 7th and 14th days after hypoxia were obtained, and the amount of the NR2A and NR2B mRNA subunits were measured the effects of molecular changes of NMDA subunits, morphological changes of neurons and/or accompanying astrocytosis were evaluated by H&E and immunohistochemical stain.
Results
: Fourteen days after hypoxia, the expression of NR2B significantly increased wheres NR2A showed distinct reduction compared with that of control rat pup. At this time, unexpectedly, neurons in CA3 region showed prominant reduction of the actual numbers and accompanied reactive astrocytosis.
Conclusion
: Alteration of NR2A and NR2B expression to hypoxic insults, suggest the possibility that changes of the NR2 subunits which can alter the fuction of the NMDA receptor play a crucial role in the occurrence of developmentally spercifix hippocampal neuronal injury

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