JAEA-Review-2010-065.pdf:15.99MB - 日本原子力研究開発機構

3-55
The Analysis of Trace Metal in a Slice of Subjected
Restraint Stress Mice by In-Air Micro-PIXE
E. Sakurai b) , K. Yanai b) , K. Ishii a) , S. Okura a) , K. Fujiki a) , H. Yamazaki a) , S. Matsuyama a) ,
N. Okamura b) , T. Kamiya c) , T. Satoh c) and K. Arakawa c)
a) Department of Quantum Science and Energy Engineering, Tohoku University,
b) Department of Pharmacology, Tohoku University School of Medicine,
c) Department of Advanced Radiation Technology, TARRI, JAEA
Stress induces the changes of circadian rhythm sleep
disorder and causes depression in human. Histaminergic
neuron system has many important roles in the brain such as
sleep-awake cycle, locomotor activity, learning and
1)
memory . The histamine receptor subtypes (H1, H2, H3
and H4) mediate these neuronal actions. We reported that
neuronal histamine is closely associated with acute and
chronic stress responses 2) . Histamine H3 receptor exits in
pre-synaptic terminals and may have alteration histamine
1)
release and modulates other neuron-systems . Therefore,
we hypothecate that histamine H3 receptor knockout
(H3-KO) mice may have resistance of stress. In this
experiment, we examined the effects of histamine H3
receptor on restraint stress induced behavioral changes in
histamine H3 receptor knockout mice and their wild type
mice. Mice were treated by 50 mg/kg /day of
5-bromo-deoxyuridine (BrdU) for 5 consecutive days, 2 h
before the behavioral studies. Bromine is a useful marker
to detect new born cells in the brain and is used widely for
neurogenesis experiments. There are some reports that the
hippocampal neurogeneses are reduced by subjected
restraint stress in rats. However, it is still unclear whether
stress induces the distribution changes of the trace elements
or not. Particle Induced X-ray Emission: PIXE is a
powerful method for the analysis of trace elements. In this
report, the trace element distributions in the brain slices of
the H3-KO mice were measured by In-Air-Micro PIXE.
In-air micro-PIXE was developed at the Takasaki Ion
Accelerators for Advanced Radiation Application (TIARA),
JAEA. Micro-PIXE allows analyzing the spatial
distribution of the elements quantitatively.
H3-KO mice were randomly divided into 3 groups.
Mice were restrained in a mouse holder for 4 h during 5
consecutive days as a physical group, and the other mice
were set next to the restrained cages as a psychological
stress group. The control mice were kept in a separate
room. After behavioral studies, mice brains were quickly
removed and each brain was cryosectioned sagittally at
16 μm thickness.
Figure 1 shows the beam irradiation image in region of
450 × 450 μm2 in the brain slice of control, subjected
psychological stress and physiological stress mice. The
image on the extreme left indicates for the control mice
(no-stress). The accumulate image of sulfur, zinc and
bromine were shown under micrograph of the each brain
slices.
JAEA-Review 2010-065
- 111 -
S
Control Psychological Physiological
stress stress
Br
Zn
Fig. 1 Micrograph of beam irradiation, zinc and bromine
image (450 × 450 μm) of H3-KO brain slices.
The amounts of trace metal in the slices are shown in
Fig. 2. The amount of bromine in the slices of subjected
restraint stress or psycological stress are almost same when
compare with no-stress control mice. Interestedly, the
amount of sulfer (data is not shown) and iron in the slice of
subjected psycological stress were significant heigher than
that of control or physiological stress mice. On the other
hand, zinc in the slices of subjected psycological stress was
significant lower than that of control or physical stress mice.
ng/cm 2
S
Zn
Br Br
Fe Cu Zn Br
Fig. 2 Comparisons of Fe, Cu, Zn and Br levels in the
brain slices of mice under stressful condition.
There are many reports that the histamine H3 receptor is
a major target for development of drugs against various
3)
disorders of the brain . However the accumulations of
trace element in the slices were significantly different under
the each stresses condition.
These results might be useful information to drug therapy
for various stress disorder.
References
1) T. Watanabe et al., Tohoku J. Exp. Med. 195 (2001)
197-217.
2) E. Sakurai et al., JAEA Takasaki Ann. Rep. 2007 (2008)
122.
3) M. B. Passani et al., Trends Pharmacol. Sci. 25 (2004)
618-625.
S
Zn