Visual input regulates the expression of basic fibroblast growth factor and its receptor

Emerging evidence indicates that the expression of trophic factors in the b rain is regulated in an activity-dependent manner, which suggests an involv ement of trophic factors in events controlled by input activity. We have in vestigated the possibility that visual sensory input impacts the expression of basic fibroblast growth factor and its receptor in the brain. Rats were maintained for seven days in darkness and then re-exposed to normal illumi nation for 0, 1, 3 or 6 h. We assessed relative levels of basic fibroblast growth factor and fibroblast growth factor receptor messenger RNAs using nu clease protection assays, and examined possible changes in the phenotypic e xpression of basic fibroblast growth factor and its receptor using immunohi stochemistry. There was a significant decrease in levels of basic fibroblas t growth factor and fibroblast growth factor receptor messenger RNAs as a r esult of dark rearing, and levels of messenger RNAs increased progressively with light re-exposure. Changes in messenger RNAs were observed primarily in the cerebral cortex (caudal portion) and were accompanied by alterations in the staining intensity and density of cells exhibiting basic fibroblast growth factor and fibroblast growth factor receptor phenotypes. Regulation of the basic fibroblast growth factor system by sensory input su ggests that basic fibroblast growth factor, and perhaps other trophic facto rs, are mediators of the effects of experience on the structure and functio n of the CNS. (C) 1998 IBRO. Published by Elsevier Science Ltd.