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Laboratory and Clinical Investigation

＜0.01）. normal function of it, thus to improve the related learning
NGF expression: there demonstrates no statistical
and memory ability. Only in high corticosterones atmosphere
significance (P＞0.05）(table2)
will them behaved hippocampus-toxicity, in turn, damage the
Discussion
structure and function of hippocampus, simultaneously lead to
The Morris water maze is one classical experiment impaired learning ability .[5,6]
to evaluate the learning and memory ability of animals’
position sense and direction sense[3,4]. The Morris water maze BDNF and NGF are two main neurotrophic factors
is also the most frequently used test in neuroscience. We
could use the ethological grades to judge changes of memory of the brain, which can support Cholinergic cells and up-
and learning induced by alteration of neurotransmitter,
anatomic structure, as well as drug intervention. In this regulate the expression of choline acetyltransterase in these
experiment，SD rats in group B recovered 1d after
isoflurane exposure, when assigned to the first test, their time cholinergic cells likewise. When the fimbria of hippocampus
to reach the platform(escape latency) and distance traversed
to reach the platform(path length) increased, when they were is cut off, BDNF can support these nerve cells continuously，
assigned to the second test, their time to cross the platform
as well as the spatial probing distance decreased. The results precipitate neurons to recover and differentiate，also to
suggest that SD rats had forgotten the actual position and
location of the platform, and further indicate the decreased maintain function. Nevertheless, if NGF is insufficient，
ability in learning and memory. However, four or seven days learning and memory deficiency will appear[7]. According
after isoflurane exposure, these rats could find the platform
rapidly and exactly again, they also appeared in the platform to our experiment: one day after isoflurane anesthesia,
area very often, which may imply the rebuilt of SD rats’
learning ability. SD rats showed poor ethological scores, which indicates

The mechanism of learning and memory is yet not the damage of hippocampus already, however such a
that clear, but studies indicates that the whole process needs
cooperation from different encephalic regions, multiple theory harm was not complete, thus could recovery under self-
also proposes that hippocampus is the core structure in learning
and memory system. When the integrality of hippocampus renovation. We assume this change was related closely with
tissue is being damaged, hippocampus-dependent learning
and memory ability may experience dramatic changes. A small the increase in plasma corticosterones, moreover, BDNF
quantity of corticosterones in the hippocampus facilitate the
expression in hippocampus increased at the same time,
Table 1 Comparison of Place navigation and Spatial probe results
thereby, we consider CORT-induced damage is accompanied
Place navigation Spatial probe
with BNDF-initiated recovery. In this experiment，NGF
Grouping latency(s) Path length(cm) latency Path length (cm)
expression displayed no change, therefore, we assume the
Group A 11.7±3.6 411.5±152.3 2.1±0.7 3129.9±171.5
damage of hippocampus makes no difference to NGF
Group B 11.4±3.7 392.0±95.8 1.6±0.6* 3633.7±249.5*
expression, nether to its growth, differentiation nor function.
Group C 12.5±4.1 403.7±102.5 2.2±1.0 3090.5±157.0
We have also accidentally discovered in our study:
Group D 23.1±5.3** 708.5±158.9** 1.4±0.9* 2587.9±165.7*
when SD rats inhaled pure oxygen for 2 hours，the plasma
Group E 13.1±3.3 402.0±95.7 2.3±1.0 3150.6±181.6
CORT is lower than the rest groups with BDNF at the
Group F 12.8±4.2 461.4±88.1 2.0±1.0 3029.1±184.8
same level as before. We can come to the conclusion: SD
*:compare with group A, P＜0.05; **:compare with group A, P＜0.01.
rats inbreathed oxygen，which enabled them to avoid
Table 2 Comparison of CORT、BDNF and NGF between each group
hypoxia-related stress reaction，plasma CORT was low.
grouping CORT（ng/ml） BDNF(pg/ml) NGF(pg/ml)
90.0±49.1 Consequently, sufficient oxygen supply remains one
Group A 663.3±209.0# 142.7±44.2 75.0±36.4
93.7±40.8 important part to protect hippocampus, tissue and improve
Group B 95.0±219.8* 126.8±48.2 75.2±50.9
92.8±26.4 internal anoxic condition.
Group C 647.3±101.4# 140.8±25.8 99.6±38.3
In summary，After isoflurane anesthesia for a relatively
Group D 865.5±127.4*# 449.5±60.5*#
short period of time, cognitive dysfunction will be induced in
Group E 658.0±258.0# 156.7±72.5
adult rats temporarily. This change may be caused by higher
Group F 534.2±167.9 170.3±75.6
plasma corticosterones and hippocampus BDNF.
*:compare with group A, P＜0.01; #:compare with group B, P＜0.01.
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