significantly increased by all the stresses. These results suggest: (1) CRF R1 and R2 mRNA in
pituitary were acutely and chronicly modulated in a biphasic manner by intermittent hypoxia, and
were acutely regulated by cold, intermittent hypoxia, restraint, cold+hypoxia and
restraint+hypoxia (2) Both CRF R1 and R2 mRNA were involved in activation of pituitary-
adrenal cortex by these stresses; (3) The significant difference of CRF R1 mRNA expression in
pituitary caused by restraint, intermittent hypoxia and cold might suggest a different role in
behavior. * This work is supported by the grant from NSFC (Major Project No. 30393134 and
Project No. 30070289; 30270232), and Specialized Research Fund for Doctoral Program of
Higher Education, China (SRFDP. No.2000033502).
33.
LEARNING AND MEMORY OF POSTNATAL MICE IN WATER MAZE AND 8-ARM
RADIAL MAZE ARE IMPROVED BY INTERMITTENT HYPOXIA . Ji-Zeng Du
1
. Zhejiang
University
1
.
Hypoxia was commonly reported to impair learning and memory of either human or animals.
In this study, we demonstrated that intermittent hypoxia (IH) improved learning and memory of
postnatal mice. Spatial learning and memory was tested in Morris water maze (MWM) task from
postnatal (P) day 36(P36) to P40 and from P85 to P89, and in an 8-arm maze from P60 to P68
after varied duration of IH. Following birth, the newborn mice were immediately exposed to
simulated IH at 2 km or 5 km in a hypobaric chamber for 1, 2, 3 or 4 weeks, respectively. In
addition, P36 mice exposed to 4-week hypoxia were used for testing LTP and CREB. The results
showed that the escape latencies in MWM of P36 mice, treated with IH for from 1 to 4 weeks,
were markedly decreased, and the retention time was significantly enhanced. Meanwhile, the
emotional adaptation to novel situations was facilitated. We found enhanced amplitude of LTP,
numbers of synapse and phosphorylated cAMP-responsive element binding protein (p-CREB) in
mice exposed to 4-week of IH at 2km or 5km. The number of error choices in the 8-arm maze
task significantly decreased in P60 to P68 mice after 2km-IH. The improvement of the IH-
induced MWM task was attenuated in P85 mice, but the facilitative trend seemed to be conserved
in 2 km IH-treated mice. These results suggest that acquisition and retention of spatial tasks may
be improved in postnatal developmental mice treated with intermittent hypoxia of 2km altitude.
The mechanism of improved spatial task performance may be due to facilitated synaptic plasticity
and triggered CREB phosphorylation in this model of mice. This work is supported by the grant
from NSFC (Major Project No. 30393134 and Project No. 30070289; 30270232)..
34.
EXPRESSIONS OF IMMUNOREACTIVE HYPOXIA-INDUCIBLE FACTOR-
1
ALPHA,
INSULIN-LIKE GROWTH FACTOR AND INSULIN-LIKE GROWTH FACTOR BINDING
PROTEIN IN LIVER OF OCHOTONA CURZONIAE and MICROTUS OECONOM. Ji-Zeng
Du
1
. Zhejiang University
1
.
Ochotona curzoniae and microtus oeconomus are native mammals to the Tibetan plateau. The
response of HIF-1a, IGF-1 and IGF-BP of these mammals to hypoxia is unclear. Hypoxic
exposure was simulated using an injection of CoCl2 (20, 40 and 60 mg/kg). Immunoreactive
proteins of HIF-1a, IGF-1 and IGF-BP were determined by in situ immunohistochemistry and
Western blot. The results showed: 1. CoCl2 markedly increased HIF-1a expression in mice liver
via i.p. injection of 20 mg/kg, which trended to reduction with increased dosage of CoCl2. CoCl2
only at 60 mg/kg significantly increased HIF-1a in Microtus oeconomus, however CoCl2 had no
significant role in HIF-1a in Ochotona curzoniae. 2. CoCl2 significantly and dose-dependently
increased liver IGF-1 expression in Microtus oeconomus, but not in O. curzoniae and mice. 3.
CoCl2 induced a significant increase of liver IGFBP-1 in mice, which was reduced with increased
dosages of CoCl2, and no change of IGFBP-1 in M.oeconomus was shown. However, a dramatic
increase of IGFBP-1 levels was caused by the all doses of CoCl2. 4. CoCl2 40 mg/kg induced
IGFBP-1 increase 6 h after injection and was still high at 12 h in O. curzoniae. These data indicat
that HIF-1 in O. curzoniae was not sensitive to CoCl2 vs. in mice, suggesting O. curzoniae has
potential adjustment to environmental hypoxia. IGF-1 protein of the liver in M.oeconomus was
