Induction of the candidate-plasticity NGFI-A protein in the adult rat superior colliculus after visual stimulation

• Published in: Brain research. Molecular brain research. 2005-02, Vol.133 (2), p.242-252
• Main Authors: Giraldi-Guimarães, Arthur, Mendez-Otero, Rosalia
• Format: Article
• Language: English
• Subjects: Analysis of Variance; Animals; Biological and medical sciences; Cell Count - methods; Cell Count - statistics & numerical data; Corticotectal projections; Dark Adaptation - physiology; Decerebrate State; Eye and associated structures. Visual pathways and centers. Vision; Eye Enucleation - methods; Functional Laterality - radiation effects; Fundamental and applied biological sciences. Psychology; Gene Expression - radiation effects; Gene Expression Regulation - radiation effects; Immediate-early genes; Immunohistochemistry - methods; In Situ Hybridization - methods; Light; Male; N-Ethylmaleimide-Sensitive Proteins; Neuronal Plasticity - radiation effects; Neurons - metabolism; Neurons - radiation effects; Photic Stimulation; Rats; Retinotectal projections; Superior Colliculi - cytology; Superior Colliculi - metabolism; Superior Colliculi - radiation effects; Synaptic plasticity; Time Factors; Transcription Factors - genetics; Transcription Factors - metabolism; Vertebrates: nervous system and sense organs; Vesicular Transport Proteins - genetics; Vesicular Transport Proteins - metabolism; Visual Pathways - metabolism; Visual Pathways - radiation effects; Visual system
• ISSN: 0169-328X; 1872-6941
• DOI: 10.1016/j.molbrainres.2004.10.020

In this work, we studied the visually driven expression of the plasticity-related transcription factor NFGI-A in the superficial layers of the rat superior colliculus (sSC) using immunohistochemistry. After dark adaptation, NGFI-A expression was completely down-regulated, indicating this protein is not constitutively expressed in the sSC. Light stimulation for 10 min after dark adaptation was insufficient to induce detectable levels of this protein. But after 30 min of light stimulation, few NGFI-A + cells were observed in the superficial layers, indicating that the minimal time of stimulation that is sufficient to induce this protein is sometime between 10 and 30 min. The number of NGFI-A + cells increased progressively, reaching a peak after 90 min. This peak is not reached if animals are returned to darkness after 30 min of stimulation, when a presumable peak in NGFI-A mRNA is reached. Light stimulation of animals in which the retinocollicular or corticocollicular projections were removed revealed that NGFI-A expression is mainly driven by retinal contralateral projections. Removal of corticocollicular projections did not cause any change in the NGFI-A expression in the ipsilateral sSC, in relation to the contralateral (control) sSC, suggesting that this pathway has a minor influence. Our results showed that NGFI-A protein expression in the sSC is entirely dependent on visual stimulation and suggests that the sSC visual circuitry is an interesting model for studies about the involvement of this transcription factor in synaptic plasticity.