Long-term dark rearing induces permanent reorganization in retinal circuitry.
Recent data challenged the assumption that light has little effect on retina development. Here, we report evidence that dark rearing permanently changes the synaptic input to GCs. A reduced spontaneous postsynaptic currents (SPSCs) frequency was found in retinal GCs from rats born and raised in the dark for three months. Glutamate antagonists (CNQX and AP-5) reversibly reduced SPSCs frequency in control and dark-reared (DR) retinae. The GABA antagonist picrotoxin (PTX) reduced SPSCs frequency in control retinas, but increased SPSCs frequency in DR, mainly by presynaptic action on excitatory currents. In DR animals exposed to normal cyclic light for 3 months, SPSCs frequency remained lower then in control rats and increased following PTX, suggesting that long-term dark rearing induces permanent modifications of the retinal circuitry. Our results strongly support the idea that light stimulation plays a role in establishing normal synaptic input to GCs.
Giovannelli
Aldo
A
Dipartimento di Medicina Sperimentale, Università di L'Aquila, via Vetoio, Coppito 2, L'Aquila 67100, Italy. giovanne@univaq.it
Di Marco
Stefano
S
Maccarone
Rita
R
Bisti
Silvia
S
D000818:Animals; D003623:Dark Adaptation / Q000502:physiology*; D003624:Darkness; D004780:Environment, Controlled; D005074:Evoked Potentials, Visual / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology*; D009473:Neuronal Plasticity / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D012165:Retinal Ganglion Cells / Q000502:physiology*; D012683:Sensory Deprivation / Q000502:physiology*