TY - JOUR T1 - Postadolescent Changes in Regional Cerebral Protein Synthesis: An <em>In Vivo</em> Study in the <em>Fmr1</em> Null Mouse JF - The Journal of Neuroscience JO - J. Neurosci. SP - 5087 LP - 5095 DO - 10.1523/JNEUROSCI.0093-05.2005 VL - 25 IS - 20 AU - Mei Qin AU - Julia Kang AU - Thomas V. Burlin AU - Chunhui Jiang AU - Carolyn Beebe Smith Y1 - 2005/05/18 UR - http://www.jneurosci.org/content/25/20/5087.abstract N2 - Methylation-induced transcriptional silencing of the fragile X mental retardation-1 (Fmr1) gene leads to absence of the gene product, fragile X mental retardation protein (FMRP), and consequently fragile X syndrome (FrX), an X-linked inherited form of mental retardation. Absence of FMRP in Fmr1 null mice imparts some characteristics of the FrX phenotype, but the precise role of FMRP in neuronal function remains unknown. FMRP is an RNA-binding protein that has been shown to suppress translation of certain mRNAs in vitro. We applied the quantitative autoradiographic l-[1-14C]leucine method to the in vivo determination of regional rates of cerebral protein synthesis (rCPS) in adult wild-type (WT) and Fmr1 null mice at 4 and 6 months of age. Our results show a substantial decrease in rCPS in all brain regions examined between the ages of 4 and 6 months in both WT and Fmr1 null mice. Superimposed on the age-dependent decline in rCPS, we demonstrate a regionally selective elevation in rCPS in Fmr1 null mice. Our results suggest that the process of synaptic pruning during young adulthood may be reflected in decreased rCPS. Our findings support the hypothesis that FMRP is a suppressor of translation in brain in vivo. ER -