INVESTIGADORES
KASANETZ Fernando
artículos
Título:
Maturation of Excitatory Synaptic Transmission of the Rat Nucleus Accumbens From Juvenile to Adult
Autor/es:
FERNANDO KASANETZ; OLIVIER J MANZONI
Revista:
JOURNAL OF NEUROPHYSIOLOGY
Editorial:
AMER PHYSIOLOGICAL SOC
Referencias:
Lugar: Bethesda; Año: 2009 vol. 101 p. 2516 - 2527
ISSN:
0022-3077
Resumen:
Precise control of synaptic strength is critical for maintaining
accurate network activity and normal brain functions. Several major
brain diseases are related to synaptic alterations in the adult brain.
Detailed descriptions of the normal physiological properties of adult
synapses are scarce, mainly because of the difficulties in performing
whole cell patch-clamp recording in brain slices from adult animals.
Here we present the portrait of excitatory synapses and intrinsic
properties of medium spiny neurons (MSNs) of the nucleus accumbens
(NAc), a central structure of the mesocorticolimbic system, from youth
(P14) to adulthood (P120). We found that intrinsic neuronal excitability
decreased over development, mainly due to an enhancement of potassium
conductance and the consequent reduction in membrane resistance. The
ratio between paired-pulse synaptic responses was similar in juvenile,
adolescent, and adult MSNs, suggesting that the probability of
neurotransmitter release was unaltered.
α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor
(AMPAR)?mediated excitatory postsynaptic currents (EPSCs) decayed more
slowly in adult MSN. In contrast, the kinetic properties and the subunit
composition of N-methyl-d-aspartate
receptor (NMDAR)?mediated EPSC in the NAc were conserved from youth to
adulthood. Changes in synaptic strength were estimated from the ratio of
AMPAR to NMDAR evoked and spontaneous EPSCs (AMPAR/NMDAR ratio).
Although both AMPAR and NMDAR EPSCs decreased over development, there
was an increase of the AMPAR/NMDAR ratio that was linked to changes in
NMDAR EPSC. Furthermore, distribution of the AMPAR/NMDAR ratio was more
heterogeneous in MSNs from adults, suggesting that synaptic strength is
continuously refined during life.