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Right isomerism of the brain in inversus viscerum mutant mice.

Kawakami R, Dobi A, Shigemoto R, Ito I - PLoS ONE (2008)

Bottom Line: However, the molecular basis of brain asymmetry remains unclear.We recently reported L-R asymmetry of hippocampal circuitry caused by differential allocation of N-methyl-D-aspartate receptor (NMDAR) subunit GluRepsilon2 (NR2B) in hippocampal synapses.This independent right isomerism of the hippocampus is the first evidence that a distinct mechanism downstream of the iv mutation generates brain asymmetry.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan.

ABSTRACT
Left-right (L-R) asymmetry is a fundamental feature of higher-order neural function. However, the molecular basis of brain asymmetry remains unclear. We recently reported L-R asymmetry of hippocampal circuitry caused by differential allocation of N-methyl-D-aspartate receptor (NMDAR) subunit GluRepsilon2 (NR2B) in hippocampal synapses. Using electrophysiology and immunocytochemistry, here we analyzed the hippocampal circuitry of the inversus viscerum (iv) mouse that has a randomized laterality of internal organs. The iv mouse hippocampus lacks L-R asymmetry, it exhibits right isomerism in the synaptic distribution of the epsilon2 subunit, irrespective of the laterality of visceral organs. This independent right isomerism of the hippocampus is the first evidence that a distinct mechanism downstream of the iv mutation generates brain asymmetry.

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Developmental asymmetry of LTP at hippocampal CA1 synapses.Schematic diagrams of the arrangement of electrodes for extracellular recording. To activate basal (Basal) or apical dendritic synapses (Apical), a stimulating electrode was placed at the stratum oriens [Stim.(SO)] or stratum radiatum [Stim.(SR)] of area CA1, respectively. fEPSPs were recorded with an extracellular electrode [Rec.(field)]. LTP was induced with tetanic stimulation at time 0 (arrow). Open and filled symbols represent 7- to 9-week-old mice and postnatal 9- to11-day-old mice, respectively. Square and circle symbols indicate recordings from basal and apical dendritic synapses, respectively. Error bars represent s.e.m. (n = 7 to 9).
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pone-0001945-g002: Developmental asymmetry of LTP at hippocampal CA1 synapses.Schematic diagrams of the arrangement of electrodes for extracellular recording. To activate basal (Basal) or apical dendritic synapses (Apical), a stimulating electrode was placed at the stratum oriens [Stim.(SO)] or stratum radiatum [Stim.(SR)] of area CA1, respectively. fEPSPs were recorded with an extracellular electrode [Rec.(field)]. LTP was induced with tetanic stimulation at time 0 (arrow). Open and filled symbols represent 7- to 9-week-old mice and postnatal 9- to11-day-old mice, respectively. Square and circle symbols indicate recordings from basal and apical dendritic synapses, respectively. Error bars represent s.e.m. (n = 7 to 9).

Mentions: To characterize the features of synapses in iv/iv mice that show the high and low sensitivity to Ro 25-6981, we analyzed the development of long-term potentiation (LTP) of field excitatory postsynaptic potentials (fEPSPs). We measured the amplitude of LTP in 7- to 9-week-old adult mice and compared it with LTP in 9- to 11-day-old pups. The ε2 subunit is the major ε subunit in the hippocampus at early postnatal ages [16], [17]. We examined slices from the left hippocampus in this experiment. fEPSPs were recorded with an extracellular electrode placed either in the stratum oriens or in the stratum radiatum of area CA1 (Figure 2). In basal synapses, the amplitudes of hippocampal LTP were similar between pups and adults (pups, 174±3%, n = 7 from 7 animals; adults, 189±3%, n = 9 from 9 animals, P>0.05) (Basal, Figure 2). In contrast, in apical synapses, the amplitudes of hippocampal LTP were greater in adults than pups (pups, 132±5%, n = 7 from 7 animals; adults, 192±4%; n = 9 from 9 animals, P<0.01) (Apical, Figure 2). Thus, LTP of Ro 25-6981 high-sensitivity synapses developed earlier than LTP in Ro 25-6981 low-sensitivity synapses. These differences in synaptic function are likely the consequence of the differential distribution of ε2 subunits at these two populations of synapses.


Right isomerism of the brain in inversus viscerum mutant mice.

Kawakami R, Dobi A, Shigemoto R, Ito I - PLoS ONE (2008)

Developmental asymmetry of LTP at hippocampal CA1 synapses.Schematic diagrams of the arrangement of electrodes for extracellular recording. To activate basal (Basal) or apical dendritic synapses (Apical), a stimulating electrode was placed at the stratum oriens [Stim.(SO)] or stratum radiatum [Stim.(SR)] of area CA1, respectively. fEPSPs were recorded with an extracellular electrode [Rec.(field)]. LTP was induced with tetanic stimulation at time 0 (arrow). Open and filled symbols represent 7- to 9-week-old mice and postnatal 9- to11-day-old mice, respectively. Square and circle symbols indicate recordings from basal and apical dendritic synapses, respectively. Error bars represent s.e.m. (n = 7 to 9).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2291575&req=5

pone-0001945-g002: Developmental asymmetry of LTP at hippocampal CA1 synapses.Schematic diagrams of the arrangement of electrodes for extracellular recording. To activate basal (Basal) or apical dendritic synapses (Apical), a stimulating electrode was placed at the stratum oriens [Stim.(SO)] or stratum radiatum [Stim.(SR)] of area CA1, respectively. fEPSPs were recorded with an extracellular electrode [Rec.(field)]. LTP was induced with tetanic stimulation at time 0 (arrow). Open and filled symbols represent 7- to 9-week-old mice and postnatal 9- to11-day-old mice, respectively. Square and circle symbols indicate recordings from basal and apical dendritic synapses, respectively. Error bars represent s.e.m. (n = 7 to 9).
Mentions: To characterize the features of synapses in iv/iv mice that show the high and low sensitivity to Ro 25-6981, we analyzed the development of long-term potentiation (LTP) of field excitatory postsynaptic potentials (fEPSPs). We measured the amplitude of LTP in 7- to 9-week-old adult mice and compared it with LTP in 9- to 11-day-old pups. The ε2 subunit is the major ε subunit in the hippocampus at early postnatal ages [16], [17]. We examined slices from the left hippocampus in this experiment. fEPSPs were recorded with an extracellular electrode placed either in the stratum oriens or in the stratum radiatum of area CA1 (Figure 2). In basal synapses, the amplitudes of hippocampal LTP were similar between pups and adults (pups, 174±3%, n = 7 from 7 animals; adults, 189±3%, n = 9 from 9 animals, P>0.05) (Basal, Figure 2). In contrast, in apical synapses, the amplitudes of hippocampal LTP were greater in adults than pups (pups, 132±5%, n = 7 from 7 animals; adults, 192±4%; n = 9 from 9 animals, P<0.01) (Apical, Figure 2). Thus, LTP of Ro 25-6981 high-sensitivity synapses developed earlier than LTP in Ro 25-6981 low-sensitivity synapses. These differences in synaptic function are likely the consequence of the differential distribution of ε2 subunits at these two populations of synapses.

Bottom Line: However, the molecular basis of brain asymmetry remains unclear.We recently reported L-R asymmetry of hippocampal circuitry caused by differential allocation of N-methyl-D-aspartate receptor (NMDAR) subunit GluRepsilon2 (NR2B) in hippocampal synapses.This independent right isomerism of the hippocampus is the first evidence that a distinct mechanism downstream of the iv mutation generates brain asymmetry.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka, Japan.

ABSTRACT
Left-right (L-R) asymmetry is a fundamental feature of higher-order neural function. However, the molecular basis of brain asymmetry remains unclear. We recently reported L-R asymmetry of hippocampal circuitry caused by differential allocation of N-methyl-D-aspartate receptor (NMDAR) subunit GluRepsilon2 (NR2B) in hippocampal synapses. Using electrophysiology and immunocytochemistry, here we analyzed the hippocampal circuitry of the inversus viscerum (iv) mouse that has a randomized laterality of internal organs. The iv mouse hippocampus lacks L-R asymmetry, it exhibits right isomerism in the synaptic distribution of the epsilon2 subunit, irrespective of the laterality of visceral organs. This independent right isomerism of the hippocampus is the first evidence that a distinct mechanism downstream of the iv mutation generates brain asymmetry.

Show MeSH