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Abstract:
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There is clinical and experimental evidence indicating
that neurocircuitries of the hippocampus
are vulnerable to hypoxia/ischemia occurring at
birth, inducing, upon re-oxygenation/re-circulation,
delayed neuronal death, but also compensatory
mechanisms, including neurogenesis. In the
present report, perinatal asphyxia was induced
by immersing foetuses-containing uterine horns
removed from ready-to-deliver rats into a water
bath at 37°C for 20 min. Some pups were delivered
immediately after the hysterectomy to be
used as non-asphyxiated caesarean-delivered
controls. The pups were sacrificed after seven
days for preparing organotypic hippocampal cultures.
The cultures were grown on a coverslip in
a medium-containing culture tube inserted in a
hole of a roller device standing on the internal
area of a cell incubator at 35°C, 10% CO2. At
days in vitro (DIV) 25-27, cultures were fixed for
assaying cell proliferation and neuronal phenotype
with antibodies against 5-bromo-2'deoxyuridine
(BrdU) and microtubule associated protein-
2 (MAP-2), respectively. Confocal microscopy
revealed that there was a 2-fold increase of BrdUpositive,
but a 40% decrease of MAP-2-positive
cells/mm3 in cultures from asphyxia-exposed,
compared to that from control animals.
Approximately 30% of BrdU-positive cells were
also positive for MAP-2 (approximately 4800
cells), mainly seen in the dentate gyrus of the hippocampus,
demonstrating a 3-fold increase of
postnatal neurogenesis, when the total amount of
double-labelled cells seen in cultures from
asphyxia-exposed animals is compared to that
from control animals. |