c-Fos expression in the visual system of the tree shrew (Tupaia belangeri).

UNLABELLED c-Fos is a nuclear phosphoprotein coded by the proto-oncogen c-fos which can be detected immunohistochemically after both physiological and pathological stimuli. This property is of great importance, because it offers a valuable tool for morphofunctional identification of activated neurons. We have studied the neuronal activity in the visual pathway of Tupaia belangeri within the following anatomical structures: retina, superior colliculus (SC), dorsal lateral geniculate nucleus (dLGN), pulvinar (Pu), parabigeminal (PBG) nucleus and primary visual cortex (V1) analyzing the c-Fos expression after exposing the tree shrews to different light stimuli (white light -control positive group-, green light, blue light and darkness conditions -control negative group-). Our findings suggest that in the retina, the ganglion cells and the cells of the inner nuclear layer respond better to blue and green light stimuli, when comparing the c-Fos expression between white, green, blue lights and darkness conditions. However, in the SC, dLGN, Pu, PBG nucleus and V1 another pattern of c-Fos expression is observed: a maximum expression for the control positive group, a minimum expression for the control negative group and intermediate expressions within the blue and green light groups. CONCLUSION the expression levels of c-Fos protein are able to show significant differences between distinct light stimuli in all anatomical structures studied (retina, SC, dLGN, Pu, PBG and V1) of T. belangeri.