Sequence of neuronal responses assessed by immunohistochemistry in the newborn rat brain after hypoxia-ischemia.
OBJECTIVE
Our purpose was to study the neuronal responses of heat shock protein-72 (a stress-inducible protein) and microtubule-associated protein-2 (a constitutive protein of the neuronal cytoskeleton) after hypoxia-ischemia and their relationship with permanent damage in the newborn rat brain.


METHODS
Seven-day-old rats were exposed to unilateral carotid artery ligation followed by 2 hours of hypoxia (8% oxygen/92% nitrogen) and then killed at time points ranging from 1 to 72 hours after injury. Brains were removed for immunohistochemical and routine staining.


RESULTS
Heat shock protein-72 appearance and microtubule-associated protein-2 disappearance occurred from 1 hour after injury, mainly in the dentate gyrus of the hippocampal formation and the cerebral cortex. Such alterations reached maximal levels at 24 hours for both proteins. Microtubule-associated protein-2 staining recovered in almost all parts of the brain. However, the hippocampal CA3 showed a delay in the responses for both proteins, and microtubule-associated protein-2 did not recover the response to immunostaining. Histologic evaluation at 72 hours after hypoxia by routine methods showed predominant damage in the hippocampal CA3.


CONCLUSIONS
Our results show that delayed responses of heat shock protein-72 and microtubule-associated protein-2 are related to a high incidence of neuronal cell loss in the hippocampal CA3 region.
Ota
A
A
Department of Obstetrics and Gynecology, Miyazaki Medical College, Japan.
Ikeda
T
T
Ikenoue
T
T
Toshimori
K
K
D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000378:metabolism / Q000503:physiopathology* / Q000648:ultrastructure; D002545:Brain Ischemia / Q000378:metabolism / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000737:chemistry / Q000648:ultrastructure; D018891:Dentate Gyrus / Q000737:chemistry / Q000648:ultrastructure; D005260:Female; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000032:analysis / Q000378:metabolism; D006624:Hippocampus / Q000737:chemistry / Q000648:ultrastructure; D000860:Hypoxia / Q000378:metabolism / Q000503:physiopathology*; D007150:Immunohistochemistry; D008869:Microtubule-Associated Proteins / Q000032:analysis / Q000378:metabolism; D009474:Neurons / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008869:Microtubule-Associated Proteins