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243 results on '"Mitsushima, Dai"'

7. Experience-specific plasticity at excitatory and inhibitory synapses onto granule cells in the dentate gyrus

Author

Han , Thiri Zin, Sakimoto, Yuya, and Mitsushima, Dai

Subjects
synaptic plasticity, contextual learning, GABA_{A} receptor, AMPA receptor, granule cells
Abstract

The hippocampal dentate gyrus has been identified to play a critical role in maintaining contextual memory in many mammalian species. To evaluate learninginduced synaptic plasticity of granule cells, we subjected male rats to an inhibitory avoidance (IA) task and prepared acute hippocampal slices. In the presence of 0.5 μM tetrodotoxin, we recorded miniature excitatory post synaptic currents (mEPSCs) and inhibitory post synaptic currents (mIPSCs) in male rats experiencing four groups: untrained, IA-trained, unpaired, and walk-through. Compared with the untrained, IA-trained, unpaired, and walk-through groups, the unpaired group significantly enhanced mean mEPSC amplitudes, suggesting the experience-induced plasticity at AMPA receptor-mediated excitatory synapses. For inhibitory synapses, both unpaired and walk-through groups significantly decreased mean mIPSC amplitudes, showing the experience-induced reduction of postsynaptic GAB A_{A} receptor-mediated currents. Unlike the plasticity at CA1 synapses, it was difficult to explain the learning- specific plasticity at the synapses. However, overall multivariate analysis using four variables of mE(I)PSC responses revealed experience-specific changes in the diversity, suggesting that the diversity of excitatory/inhibitory synapses onto granule cells differs among the past experience of animals include the learning. In comparison with CA1 pyramidal neurons, granule cells consistently showed greater amplitude and frequency of mE(I)PSCs. Fluctuation analysis further revealed that granule cells provide more postsynaptic AMPA receptor channels and greater single-channel current of GABA_{A} receptors of than CA1 pyramidal neurons. These findings show functional differences between two types of principal cells in the hippocampus.

Published
2022

12. Motor training promotes both synaptic and intrinsic plasticity of layer V pyramidal neurons in the primary motor cortex.

Author

Kida, H., Kawakami, R., Sakai, K., Otaku, H., Imamura, K., Han, Thiri‐Zin, Sakimoto, Y., and Mitsushima, Dai

Subjects
PYRAMIDAL neurons, MOTOR neurons, NEUROPLASTICITY, MOTOR cortex, DENDRITIC spines, METHYL aspartate receptors, MOTOR learning
Abstract

Layer V neurons in the primary motor cortex (M1) are important for motor skill learning. Since pretreatment of either CNQX or APV in rat M1 layer V impaired rotor rod learning, we analysed training‐induced synaptic plasticity by whole‐cell patch‐clamp technique in acute brain slices. Rats trained for 1 day showed a decrease in small inhibitory postsynaptic current (mIPSC) frequency and an increase in the paired‐pulse ratio of evoked IPSCs, suggesting a transient decrease in presynaptic GABA release in the early phase. Rats trained for 2 days showed an increase in miniature excitatory postsynaptic current (mEPSC) amplitudes/frequency and elevated AMPA/NMDA ratios, suggesting a long‐term strengthening of AMPA receptor‐mediated excitatory synapses. Importantly, rotor rod performance in trained rats was correlated with the mean mEPSC amplitude and the frequency obtained from that animal. In current‐clamp analysis, 1‐day‐trained rats transiently decreased the current‐induced firing rate, while 2‐day‐trained rats returned to pre‐training levels, suggesting dynamic changes in intrinsic properties. Furthermore, western blot analysis of layer V detected decreased phosphorylation of Ser408–409 in GABAA receptor β3 subunits in 1‐day‐trained rats, and increased phosphorylation of Ser831 in AMPA receptor GluA1 subunits in 2‐day‐trained rats. Finally, live‐imaging analysis of Thy1‐YFP transgenic mice showed that the training rapidly recruited a substantial number of spines for long‐term plasticity in M1 layer V neurons. Taken together, these results indicate that motor training induces complex and diverse plasticity in M1 layer V pyramidal neurons. Key points: Here we examined motor training‐induced synaptic and intrinsic plasticity of layer V pyramidal neurons in the primary motor cortex.The training reduced presynaptic GABA release in the early phase, but strengthened AMPA receptor‐mediated excitatory synapses in the later phase: acquired motor performance after training correlated with the strength of excitatory synapses rather than inhibitory synapses.As to the intrinsic property, the training transiently decreased the firing rate in the early phase, but returned to pre‐training levels in the later phase.Western blot analysis detected decreased phosphorylation of Ser408‐409 in GABAA receptor β3 subunits in the acute phase, and increased phosphorylation of Ser831 in AMPA receptor GluA1 subunits in the later phase.Live‐imaging analysis of Thy1‐YFP transgenic mice showed rapid and long‐term spine plasticity in M1 layer V neurons, suggesting training‐induced increases in self‐entropy per spine. [ABSTRACT FROM AUTHOR]

Published
2023
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32. gamma-aminobutyric acid is an inhibitory neurotransmitter restricting the release of luteinizing hormone-releasing hormone before the onset of puberty

Author

Mitsushima, Dai, Hei, David L., and Terasawa, Ei

Subjects
Neurotransmitters -- Research, Gonadotropin releasing hormone -- Research, GABA -- Receptors, Science and technology
Abstract

Analyses of conscious female monkeys at the prepubertal and pubertal phases, utilizing a push-pull perfusion technique, confirmed the presence of a strong gamma-amino butyric acid (GABA) blocking of the luteinizing hormone-releasing hormone (LHRH) neurosecretory system in the prepubertal phase. Infusions of GABAa, and not GABAb, antagonist effects LHRH secretion through the elimination of the endogenous GABA blocking. High endogenous GABA levels render exogeneous GABA ineffective.

Published
1994

44. Astrocyte-expressed FABP7 regulates dendritic morphology and excitatory synaptic function of cortical neurons

Author

Ebrahimi, Majid, primary, Yamamoto, Yui, additional, Sharifi, Kazem, additional, Kida, Hiroyuki, additional, Kagawa, Yoshiteru, additional, Yasumoto, Yuki, additional, Islam, Ariful, additional, Miyazaki, Hirofumi, additional, Shimamoto, Chie, additional, Maekawa, Motoko, additional, Mitsushima, Dai, additional, Yoshikawa, Takeo, additional, and Owada, Yuji, additional

Published
2015
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