Somatosensory and Visual Deprivation Each Decrease the Density of Parvalbumin Neurons and Their Synapse Terminals in the Prefrontal Cortex and Hippocampus of Mice

In the phenomenon known as cross-modal plasticity, the loss of one sensory system is followed by improved functioning of other intact sensory systems. MRI and functional MRI studies suggested a role of the prefrontal cortex and the temporal lobe in cross-modal plasticity. We used a mouse model to examine the effects of sensory deprivation achieved by whisker trimming and visual deprivation achieved by dark rearing in neonatal mice on the appearance of parvalbumin (PV) neurons and the formation of glutamic acid decarboxylase 67 (GAD67)-positive puncta around pyramidal neurons in the prefrontal cortex and hippocampus. Whisker trimming, but not dark rearing, decreased the density of PV neurons in the hippocampus at postnatal day 28 (P28). In the prefrontal cortex, whisker trimming and dark rearing decreased the density of PV neurons in layer 5/6 (L5/6) at P28 and in L2/3 at P56, respectively, whereas dark rearing increased the density of PV neurons in L5/6 at P56. Whisker trimming decreased the density of GAD67-positive puncta in CA1 of the hippocampus at both P28 and P56 and in L5/6 of the prefrontal cortex at P28. Dark rearing decreased the density of GAD67-positive puncta in CA1 of the hippocampus and in both L2/3 and L5/6 of the prefrontal cortex at P28, and in L2/3 of the prefrontal cortex at P56. These results demonstrate that somatosensory or visual deprivation causes changes in the PV-interneuronal network in the mouse prefrontal cortex and hippocampus. The results also suggest that the alteration of the PV-interneuronal network, especially in the prefrontal cortex, may contribute to cross-modal plasticity

Helping-Like Behaviour in Mice Towards Conspecifics Constrained Inside Tubes

Prosocial behaviour, including helping behaviour, benefits others. Recently, helping-like behaviour has been observed in rats, but whether it is oriented towards rescue, social contact with others, or other goals remains unclear. Therefore, we investigated whether helping-like behaviour could be observed in mice similar to that in rats. Because mice are social animals widely used in neuroscience, the discovery of helping-like behaviour in mice would be valuable in clarifying the psychological and biological mechanisms underlying pro-sociability. We constrained mice inside tubes. Subject mice were allowed to move freely in cages with tubes containing constrained conspecifics. The subject mice released both cagemates and stranger mice but did not engage in opening empty tubes. Furthermore, the same behaviour was observed under aversive conditions and with anesthetised conspecifics. Interestingly, hungry mice opened the tubes containing food before engaging in tube-opening behaviour to free constrained conspecifics. Mice showed equal preferences for constrained and freely moving conspecifics. We demonstrated for the first time that mice show tube-opening behaviour. Furthermore, we partly clarified the purpose and motivation of this behaviour. An effective mouse model for helping-like behaviour would facilitate research on the mechanisms underlying prosocial behaviour

Layer-specific expression of extracellular matrix molecules in the mouse somatosensory and piriform cortices

In the developing central nervous system (CNS), extracellular matrix (ECM) molecules have regulating roles such as in brain development, neural-circuit maturation, and synaptic-function control. However, excluding the perineuronal net (PNN) area, the distribution, constituent elements, and expression level of granular ECM molecules (diffuse ECM) present in the mature CNS remain unclear. Diffuse ECM molecules in the CNS share the components of PNNs and are likely functional. As cortical functions are greatly region-dependent, we hypothesized that ECM molecules would differ in distribution, expression level, and components in a region- and layer-dependent manner. We examined the layer-specific expression of several chondroitin sulfate proteoglycans (aggrecan, neurocan, and brevican), tenascin-R, Wisteria floribunda agglutinin (WFA)-positive molecules, hyaluronic acid, and link protein in the somatosensory and piriform cortices of mature mice. Furthermore, we investigated expression changes in WFA-positive molecules due to aging. In the somatosensory cortex, PNN density was particularly high at layer 4 (L4), but not all diffuse ECM molecules were highly expressed at L4 compared to the other layers. There was almost no change in tenascin-R and hyaluronic acid in any somatosensory-cortex layer. Neurocan showed high expression in L1 of the somatosensory cortex. In the piriform cortex, many ECM molecules showed higher expression in L1 than in the other layers. However, hyaluronic acid showed high expression in deep layers. Here, we clarified that ECM molecules differ in constituent elements and expression in a region- and layer-dependent manner. Region-specific expression of ECM molecules is possibly related to functions such as region-specific plasticity and vulnerability

Attenuated Sensory Deprivation-induced Changes of Parvalbumin Neuron Density in the Barrel Cortex of FcγRllB-deficient Mice

Recent studies have demonstrated the important role of immune molecules in the development of neuronal circuitry and synaptic plasticity. We have detected the presence of FcγRllB protein in parvalbumin- containing inhibitory interneurons (PV neurons). In the present study, we examined the appearance of PV neurons in the barrel cortex and the effect of sensory deprivation in FcγRllB-deficient mice (FcγRllB-/-) and wild-type mice. There was no substantial difference in the appearance of PV neurons in the developing barrel cortex between FcγRllB-/- and wild-type mice. Sensory deprivation from immediately after birth (P0) or P7 to P12-P14 induced an increase in PV neurons. In contrast, sensory deprivation from P7 or P14 to P28, but not from P21 to P28, decreased PV neurons in wild-type mice. However, sensory deprivation from P0 or P7 to P12-P14 did not increase PV neurons and sensory deprivation from P7 or P14 to P28 did not decrease or only modestly decreased PV neurons in FcγRllB-/- mice. The results indicate that expression of PV is regulated by sensory experience and the second and third postnatal weeks are a sensitive period for sensory deprivation, and suggest that FcγRllB contributes to sensory experience-regulated expression of PV

Alpha-pinene and dizocilpine (MK-801) attenuate kindling development and astrocytosis in an experimental mouse model of epilepsy

Understanding the molecular and cellular mechanisms involved during the onset of epilepsy is crucial for elucidating the overall mechanism of epileptogenesis and therapeutic strategies. Previous studies, using a pentylenetetrazole (PTZ)-induced kindling mouse model, showed that astrocyte activation and an increase in perineuronal nets (PNNs) and extracellular matrix (ECM) molecules occurred within the hippocampus. However, the mechanisms of initiation and suppression of these changes, remain unclear. Herein, we analyzed the attenuation of astrocyte activation caused by dizocilpine (MK-801) administration, as well as the anticonvulsant effect of α-pinene on seizures and production of ECM molecules. Our results showed that MK-801 significantly reduced kindling acquisition, while α-pinene treatment prevented an increase in seizures incidences. Both MK-801 and α-pinene administration attenuated astrocyte activation by PTZ and significantly attenuated the increase in ECM molecules. Our results indicate that astrocyte activation and an increase in ECM may contribute to epileptogenesis and suggest that MK-801 and α-pinene may prevent epileptic seizures by suppressing astrocyte activation and ECM molecule production

Anti-stress effects of the hydroalcoholic extract of Rosa gallica officinalis in mice

Rosa gallica, a plant of the Rosa genus, has been used widely since the 13th century and is cultivated in many areas as a medicinal plant for the preparation of herbal medicines. However, details of the neuropsychological effects of R. gallica remain unclear; therefore we aimed to investigate the neuropsychological effects of a water-soluble extract of R. gallica in male C57BL/6N mice under normal conditions and under chronic stress. We administered a water-soluble extract of R. gallica to mice and performed a series of behavioral experiments to compare the treated animals with the untreated controls. No significant differences in activity level, anxiety-like behavior, depression-like behavior, body weight, and body temperature were observed between R. gallica-treated mice and control mice. However, in mice subjected to chronic stress, the observed decrease in activity was smaller in the R. gallica-treated mice than in the control mice. The oral administration of R. gallica did not affect the normal behavior of mice. However, when the mice were subjected to stress, R. gallica exerted an anti-stress effect. Therefore, R. gallica has potential as a medicinal plant for the purpose of stress prevention

Oncogenic FGFR1 mutation and amplification in common cellular origin in a composite tumor with neuroblastoma and pheochromocytoma

Neuroblastoma (NB) and pheochromocytoma (PCC) are derived from neural crest cells (NCCs); however, composite tumors with NB and PCC are rare, and their underlying molecular mechanisms remain unknown. To address this issue, we performed exome and transcriptome sequencing with formalin-fixed paraffin-embedded (FFPE) samples from the NB, PCC, and mixed lesions in a patient with a composite tumor. Whole-exome sequencing revealed that most mutations (80%) were shared by all samples, indicating that NB and PCC evolved from the same clone. Notably, all samples harbored both mutation and focal amplification in the FGFR1 oncogene, resulting in an extraordinarily high expression, likely to be the main driver of this tumor. Transcriptome sequencing revealed undifferentiated expression profiles for the NB lesions. Considering that a metastatic lesion was also composite, most likely, the primitive founding lesions should differentiate into both NB and PCC. This is the first reported case with composite-NB and PCC genetically proven to harbor an oncogenic FGFR1 alteration of a common cellular origin

3D reconstruction from images of many wave absorbing blocks

第10回IEEE広島支部学生シンポジウム(HISS), ポスター ; 開催場所:広島 ; 開催日:2008年11月21-23