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Titolo:
DEVELOPMENTAL-CHANGES IN MEMBRANE-PROPERTIES AND POSTSYNAPTIC CURRENTS OF GRANULE CELLS IN RAT DENTATE GYRUS
Autore:
LIU YB; LIO PA; PASTERNAK JF; TROMMER BL;
Indirizzi:
EVANSTON HOSP CORP,DIV NEUROL,2650 RIDGE AVE EVANSTON IL 60201 EVANSTON HOSP CORP,DIV PEDIAT NEUROL EVANSTON IL 60201 NORTHWESTERN UNIV,SCH MED,DEPT PEDIAT CHICAGO IL 60611 NORTHWESTERN UNIV,SCH MED,DEPT NEUROL CHICAGO IL 60611
Titolo Testata:
Journal of neurophysiology
fascicolo: 2, volume: 76, anno: 1996,
pagine: 1074 - 1088
SICI:
0022-3077(1996)76:2<1074:DIMAPC>2.0.ZU;2-#
Fonte:
ISI
Lingua:
ENG
Soggetto:
LONG-LASTING POTENTIATION; GABAERGIC NEURONS; PATCH-CLAMP; HIPPOCAMPAL-FORMATION; POSTNATAL-DEVELOPMENT; TERM POTENTIATION; FASCIA DENTATA; BASKET CELLS; IN-VITRO; MATURATION;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
Y.B. Liu et al., "DEVELOPMENTAL-CHANGES IN MEMBRANE-PROPERTIES AND POSTSYNAPTIC CURRENTS OF GRANULE CELLS IN RAT DENTATE GYRUS", Journal of neurophysiology, 76(2), 1996, pp. 1074-1088

Abstract

1. Whole cell patch-clamp recordings were used to study dentate gyrusgranule cells in hippocampal slices from juvenile rats (postnatal days 8-32). Membrane properties were measured with the use of current-clamp recordings and were correlated with the morphology of a subgroup ofneurons filled with biocytin. The components of the postsynaptic currents (PSCs) induced by medial perforant path stimulation were characterized with the use of specific receptor antagonists in voltage-clamp recordings. 2. Granule cells located in the middle third of the superior blade of stratum granulosum from the rostral third of hippocampus were divided into three groups according to their input resistance (IR). Neurons with low IR (206 +/- 182 M Omega, mean +/- SD) had hyperpolarized resting membrane potentials (-82 +/- 7 mV) and high-amplitude action potentials (108 +/- 23 mV). Neurons with high IR (1,259 +/- 204 M Omega) had more depolarized resting membrane potentials (-54 +/- 6 mV)and lower-amplitude action potentials (71 +/- 10 mV). Neurons with intermediate IR (619 +/- 166 M Omega) also had intermediate resting membrane potentials (-63 +/- 7 mV) and action potential amplitudes (86 +/-14 mV). Low-IR neurons became increasingly prevalent with advancing postnatal age, but neurons from each group could be found throughout the entire period under study. 3. Morphological studies of low-IR neurons revealed an extensive dendritic arborization that traversed the entire molecular layer and was characteristic of mature granule cells. High-IR cells had smaller somata and short, simple dendritic arborizationthat incompletely penetrated the molecular layer and were classified as immature. Intermediate-IR cells had morphological features of intermediate maturity. 4. The initial phase of the PSC evoked at -80 mV wasa fast inward current that was comparable with respect to latency to peak, latency to onset, and 10-90% rise time in neurons of all maturities held at -80 mV. This current was 6-cyano-7-nitroquinoxaline-2,3-dione sensitive. 5. The decay phases of PSCs at -80 mV varied with neuronal maturity. Mature neurons had monoexponential decays (tau=8.9+/-3.6). Intermediate and immature neurons had prominent later inward currents that resulted in slower decays. In the case of the immature neurons, the inward current during the decay phase could be separated from the initial fast inward peak. The later inward currents in intermediate and immature neurons were bicuculline sensitive. 6. With the use of uniform ionic conditions of the extracellular and patch solutions, current-voltage relations and reversal potentials for pharmacologically isolated lpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), N-methyl-D-aspartate (NMDA), and gamma-aminobutyric acid-A (GABA(A)) currents were comparable across all cell maturities. Calculated ratios for peak GABA(A)/NMDA/AMPA currents decreased significantly with maturation as follows: 9.4+/-2.9/1.4 +/-0.5/1.0 for immature cells, 7.2+/-2.5/1.5+/-0.7/1.0 for intermediate cells, and 2.0+/- 1.2/0.9+/-0.4/1.0 for mature cells. 7. GABA current was mediated both by polysynaptic activation of interneurons and by direct activation of interneurons withmonosynaptic input onto granule cells. The proportional contributionsof mono- and polysynaptic GABA to total GABA were comparable across all cell maturities; latency to peak GABA current decreased with increasing cell maturity for both mono- and polysynaptic components. 8. We conclude that PSCs evoked in granule cells by medial perforant path activation in neurons of all maturities consist of both glutamatergic andGABAergic components. PSCs are dominated by GABAergic neurotransmission in immature granule cells, and the contribution of glutamatergic neurotransmission increases with neuronal maturation. The greater ratio of peak GABA(A) to glutamate currents and the longer time interval between their respective peaks combine to produce a distinctive PSC shapein the immature compared with mature granule cells.

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Documento generato il 30/11/20 alle ore 10:14:13