Neuronal cell death in hippocampus induced by homocysteic acid in immature rats.
OBJECTIVE
To examine the morphologic alterations in the cerebral cortex and hippocampus of immature rats 6 days after the generalized clonic-tonic seizures induced by homocysteic acid (HCA).


METHODS
Seizures were induced by bilateral intracerebroventricular infusion of HCA (600 nmol per each side) in 12-day-old rats. After 6 days, rat pups were transcardially perfused under deep ether anesthesia with heparinized normal saline and subsequently with the fixation solution (4% paraformaldehyde in phosphate buffer, pH 7.4, for light microscopy) or with Karnovsky's solution (4% paraformaldehyde and 2% glutaraldehyde in phosphate buffer, pH 7.4, for electron microscopic analysis). Nissl stain and the DNA-specific dye bis-benzimide (Hoechst 33342) were used.


RESULTS
No pathologic changes were found in the cerebral cortex, whereas serious alterations occurred in the hippocampus. A total loss of CA3 pyramidal cells was observed, with marked changes in the CA1 region and dentate gyrus. A prominent glial reaction was seen in many regions of the hippocampal formation. A slight dilatation of the cerebral ventricles was noticed in some experimental as well as control animals. In the granule cell layer of the dentate gyrus, neurons with segmented or fragmented nuclei in various stages of degeneration were detected, displaying the features of apoptotic death.


CONCLUSIONS
These findings demonstrate the vulnerability of the immature rat brain, which most likely reflects both the direct neurotoxic effect of HCA and prolonged seizure activity. The relative contribution of these two factors still remains to be assessed.
Langmeier
Milos
M
Institute of Physiology, First Medical School, Charles University, Prague, Czech Republic. mlangm@lfl.cuni.cz
Folbergrová
Jaroslava
J
Haugvicová
Renata
R
Pokorný
Jaroslav
J
Mares
Pavel
P
D000818:Animals; D000831:Animals, Newborn; D017209:Apoptosis / Q000502:physiology; D002452:Cell Count; D002467:Cell Nucleus / Q000473:pathology; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects / Q000473:pathology; D018891:Dentate Gyrus / Q000166:cytology / Q000187:drug effects / Q000473:pathology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000473:pathology*; D006710:Homocysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D009410:Nerve Degeneration / Q000473:pathology; D009457:Neuroglia / Q000166:cytology / Q000473:pathology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000473:pathology*; D017966:Pyramidal Cells / Q000166:cytology / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D012640:Seizures / Q000139:chemically induced* / Q000473:pathology
D006710:Homocysteine; C007956:homocysteic acid