Edited on the basis: <http://www.ukrv.de/esc/abstracts/neu/n8.html>
Neuroscience
VICTORIA BERETZKY
H-7622 PÉCS
48-as tér 4.
HUNGARY
V. Beretzky, V. Tamásy
Department of Physiology, University Medical School of Pécs, Hungary
THE LONG-TERM EFFECT OF NEWBORN HYPEROXYGENISATION
ON THE DEVELOPMENT OF LEARNING ABILITY, MEMORY AND BEHAVIOR IN THE RAT
There are an increasing number of experimental
results indicating that neonatal hyperoxygenisation, - beside the striking
lesion of retina (retinopathia premature, OP) - permanently influences
the activity of several cerebral enzymes and neurotransmitter systems playing
important role in the development of learning ability, memory and behavior.
Our experiments are in the first investigations dealing with the long-term
effects of newborn hyperoxygenisation on the above mentioned functions
in the rat.
Materials and methods: the experiments
were done with albino CFI and pigmented Long-Evans rat strains. Newborn
rats were placed - together with their mother - in an incubator for two
hours a day on the 1.-7., or on the 4.-7. postnatal days after birth. 100%
(2 atm.) oxygen was led into the incubator for the treated, and
normal air for the control rats. Then specific learning and memory tests
(modified open field, different types of passive avoiding learning, Morris
type Water Maze learning), and adaptive behavior investigations were performed
in the prepubertal (35-40 day) and young adult (2 month) age. Furthermore
morphological investigation of the hippocampus was performed by using Timm-stain
technique, and the structure of the retina was histologically analyzed
by light microscope.
Results: we found significant
hyperactivity, disturbance of explorative behaviour, adaptational and discriminative
disorders in the oxygen-treated groups in both of the rat strains compared
to the control groups. There was difference in the results between the
groups treated with oxygen on 1.-7. days and 4.-7. days, and difference
between the treated and control rats. We also found specific spatial memory
dysfunction, learning deficit decreased memory-recalling capacity indicating
the functional lesion of the basal forebrain and hippocampal formation,
but the functional-disorders were not accompanied by histologically detectable
differencies in these brain structures. There was also no morphological
difference between the layer-structure of the retina in the treated and
control rats.
Conclusions: our results
show that complex memory-function and behaviour investigations are able
to reveal the long-term harmful effect of newborn hyperoxygenisation on
the memory capacity, learning ability and adaptational behaviour.
The infants of the rat are born
in the early stage of the development of central nervous system, therefore
this experimental model is applicable to help us to a better understand
of the development and neuronal vulnerability of the cerebral structure
of human premature infants.