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Motor protein KIFA is essential for hippocampal synaptogenesis
and learning enhancement in an enriched environment
Environmental enrichment causes a variety of effects on brain structure and
function. Brainderived neurotrophic factor BDNF plays an important role
in enrichmentinduced neuronal changes; however, the precise mechanism
underlying these effects remains uncertain. In this study, a specific upregulation of
kinesin superfamily motor protein 1A KIF1A was observed in the hippocampi
of mice kept in an enriched environment and, in hippocampal neurons in vitro,
BDNF increased the levels of KIF1A and of KIF1Amediated cargo transport.
Analysis of Bdnf +/-
and Kif1a +/- mice revealed that a lack of KIF1A upregulation
resulted in a loss of enrichmentinduced hippocampal synaptogenesis and learning
enhancement. Meanwhile, KIF1A overexpression promoted synaptogenesis via
the formation of presynaptic boutons. These findings demonstrate that KIF1A
is indispensable for BDNFmediated hippocampal synaptogenesis and learning
enhancement induced by enrichment. This is a new molecular motormediated
presynaptic mechanism underlying experiencedependent neuroplasticity.
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Activationspecific Changes of Angiotensin II Receptors in Mouse
Cerebellum and Adrenal Glands with In Vivo Cryotechnique
Zheng Huang, Nobuo Terada, Yurika Saitoh, Jiaorong Chen, Shinichi Ohno
Department of Anatomy and Molecular Histology, Interdisciplinary Graduate
School of Medicine and Engineering, University of Yamanashi
We have performed immunohistochemical analyses of AT1/2R with molecular
activationspecific antibodies in living mouse cerebellum and adrenal glands under
normal or hypoxic conditions with “in vivo cryotechnique” IVCT followed by
freezesubstitution FS. In the cerebellum, outer molecular layers and some areas
around Purkinje cells were immunostained as dotted patterns, which were closely
related to Bergmann glia. At 5 and 10 min after hypoxia, the immunoreactivity
was remarkably reduced, though it was still remained the same in the adrenal
glands at 15min after hypoxia. This immunohistochemical approach with IVCT
FS enabled us to perform their precise analyses.
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Nodose ganglion cells expressing melanocortin receptor send their
fibers to the pancreatic islets in the mouse
Toshiko Tsumori, Tatsuro Oka, Jianguo Niu, Yukihiko Yasui
Dept. Anat. & Morphol. Neurosci., Shimane Univ. Sch. Med.
Melanocortin system including melanocortin4 receptor MC4R plays a
crucial role in the control of feeding and energy expenditure. Using a transgenic
mouse model in which green fluorescent protein GFP is produced under the
control of the MC4R promoter, we recently reported that the dorsal motor
nucleus of the vagus nerve contains many MC4Rexpressing neurons which
project to the intrapancreatic ganglia. In this study, we examined whether or
not MC4Rexpressing nodose ganglion cells send their fibers to the pancreas.
Using retrograde tracing with chorela toxin B subunit in combination with
immunohistochemistry for GFP, we demonstrated that some of the nodose
ganglion cells sending their fibers to the pancreas showed GFP immunoreactivity.
Using double immunofluorecence staining for insulin and GFP, we also showed
that GFPimmunoreactive ir boutonlike varicosities were distributed within
the pancreatic islets and some of them were in close apposition to insulinir cell
bodies. The previous and present results suggest that both of the vagal afferent
and efferent neurons expressing MC4R may be closely related to exocrine and
endocrine pancreatic functions on energy expenditure.
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Runx
Runx runt Runx13 3
Runx1 Runx1
12.5 E12.5
Runx1
Runx1 Runx1 -/- ::TgE12.5
Runx1 E17.5
Runx1 Runx1
Runx1
Runx1
NeurofilamentM
VAChTRunx1 +/+ ::Tg Runx1 -/- ::Tg
3
Runx1 -/- ::Tg VAChT
Runx1 +/+ ::Tg
Runx1 -/- ::Tg Runx1
P
A
1 2 1
1
2
A Cholecystokinin A receptor: CCKAR
CCK CCKAR mRNA
nodose ganglion: NGNG CCK
binding site
CCKAR CCKAR
CCK
AR CCKAR
2
VGluT2
CCKAR
CCKAR NG
B
NG CCKAR/
VGluT2 CCKAR
CCKAR
NG
P
Features of boutons distribution along axons of neurons in the
caudal nucleus of tractus solitarius of the rat
A large amount of the information processing that happens in the brain occurs
in the microcircuitry. For comprehensive understanding of the mechanisms
regulating connectivity among neurons within the microcircuitry, it is essential
to elucidate how pre and postsynaptic components are connected. In this study,
to understand the rules by which axons make synapses, we investigated the
arrangement of synaptic boutons on axons of biocytinfilled neurons in the caudal
nucleus of the tractus solitarius cNTS of medulla oblongata. We analyzed the
length and distribution of interbouton intervals ibi under the light microscope.
The overall average length of ibi was 4.7 μm and varied by neurons ranged
from 2.8 to 8.1 μm. Although there was considerable variation in the average
length of ibi among neurons, a general scaling relationship between the standard
deviation and the average was found. In addition, the distribution of ibi was
characteristically skewed and the tail of that was fitted well to an exponential
distribution. These results suggest that the synaptic boutons along axons of cNTS
neurons are distributed in a fundamentally similar manner, a random manner.