Quantitative Non-radioactive In Situ Hybridization Study of GAP-43 and SCG10 mRNAs in the Cerebral Cortex of Adult and Infant Macaque Monkeys

We performed non-radioactive in situ hybridization histochemistry in several areas that include both the association areas and the lower sensory areas of monkey cerebral cortex, and investigated the localization of neurons expressing two growth-associated proteins: GAP-43 and SCG10. Both GAP-43 and SCG10 mRNAs were observed in both pyramidal and non-pyramidal neurons. Prominent hybridization signals for GAP-43 mRNA were observed in layers II-VI of the adult association areas: the prefrontal areas (FD), the temporal (TE) and the parietal (PG) association areas. The signals for GAP-43 mRNA were weak in layers I-III of the adult primary somatosensory area (PB) and primary (OC) and secondary (OB) visual areas, and cells with prominent signals were observed in layers IV-VI. The prominent signals for SCG10 mRNA were observed in layers IV-VI of all areas examined. These results suggest that the expression pattern of GAP-43 mRNA, but not that of SCG10 mRNA, may be related to the functional difference between association and lower sensory areas of adult cortex. In the infant cortex (postnatal days 2, 8 and 31), the signals for both mRNAs were intense in layers II-VI of all areas. Therefore, layer-specific expressions of GAP-43 and SCG10 mRNAs are established after the first postnatal month.