The Journal of Neuroscience, May 1, 2003, 23(9):3566
BRIEF COMMUNICATION
Effects of Neurotrophins on Synaptic Protein Expression in the
Visual Cortex of Dark-Reared Rats
Tiziana
Cotrufo,
Alessandro
Viegi,
Nicoletta
Berardi,
Yuri
Bozzi,
Laura
Mascia, and
Lamberto
Maffei
Scuola Normale Superiore, 56126 Pisa, Italy, Istituto di
Neuroscienze, Consiglio Nazionale delle Ricerche, 56100 Pisa, Italy,
and Dipartimento di Psicologia, Universita' di Firenze, 50123 Firenze,
Italy
Total lack of visual experience [dark rearing (DR)] is
known to prolong the critical period and delay development of sensory functions in mammalian visual cortex. Recent results show that neurotrophins (NTs) counteract the effects of DR on functional properties of visual cortical cells and exert a strong control on
critical period duration. NTs are known to modulate the development and
synaptic efficacy of neurotransmitter systems that are affected by DR.
However, it is still unknown whether the actions of NTs in dark-reared
animals involve interaction with neurotransmitter systems. We have
studied the effects of DR on the expression of key molecules in the
glutamatergic and GABAergic systems in control and NT-treated animals.
We have found that DR reduced the expression of the NMDA receptor 2A
subunit and its associated protein PSD-95 (postsynaptic density-95), of
GRIP (AMPA glutamate receptor interacting protein), and of the
biosynthetic enzyme GAD (glutamic acid decarboxylase).
Returning dark-reared animals to light for 2 hr restored normal
expression of the above-mentioned proteins almost completely. NT
treatment specifically counteracts DR effects; NGF acts
primarily on the NMDA system, whereas BDNF acts primarily on the
GABAergic system. Finally, the action of NT4 seems to involve both
excitatory and inhibitory systems. These data demonstrate that
different NTs counteract DR effects by modulating the expression of key molecules of the excitatory and inhibitory neurotransmitter systems.
Key words:
neurotrophins; GAD; NMDAR; PSD-95; GRIP; dark
rearing; visual experience; visual cortex
Copyright © 2003 Society for Neuroscience 0270-6474/03/2393566-06$05.00/0