1992 Fiscal Year Final Research Report Summary
Patch clamp studies on the developmental changes in inhibitory postsynaptic receptors of rat spinal cord
| Project/Area Number |
03454128
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Neurophysiology and muscle physiology
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
TAKAHASHI Tomoyki Kyoto University Faculty of Medicine Lecturer, 医学部, 講師 (40092415)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Spinal Cord / Slice / Patch Clamp / IPSCs / Glycine Receptor / Development / cRNAs |
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| Research Abstract |
Patch clamp whole-cell recordings were made from dorsal hornneurones of rat spinal cord in thin slices. Glycinergic inhibitory postsynaptic currents (IPSCs) were evoked by stimulating a neighboring interneurone in the presence of CNQX and bicuculline. The rise (10 %- 90 %) and mean decay time constants were compared in animals of various age ranging from 20 embryonic day (20E) to 22 postnatal day (22P). No significant change was observed for the rise time with ages, whereas the mean time constant of decay was markedly shortened as the animals develop. The mean value was 27 ms at 20E and 5.9 ms at 16P. In pararell with the decay time constant of IPSCs, the mean open time of glycine-gated channels recorded from outside-out patches excised from spinal neurones was markedly shortened as animals mature. To study a molecular basis underlying these changes, we have expressed homomeric glycine receptors in Xenopus oocytes by injecting cRNAs encoding each adult type, alpha1, and fetal type, alpha2, subunit. With studies of molecular biology, alpha2 subunit is known to be replaced by alpha1 subunit within 3 weeks postnatally. Glycine-gated single channel currents recorded from outside-out patches excised from oocytes expressed with alpha1 receptor were markedly shorter than those from alpha2 subunit. It is concluded that alpha2/alpha1 switching of glycine receptor subunit shotens the open time of glycne receptor channels thereby shortening the time course of glycinergic IPSCs.
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