BASIC FIBROBLAST GROWTH-FACTOR (BFGF) AND 2 OF ITS RECEPTORS, FGFR1 AND FGFR2 - GENE-EXPRESSION IN THE RAT-BRAIN DURING POSTNATAL-DEVELOPMENT AS DETERMINED BY QUANTITATIVE RT-PCR

Regional and temporal patterns of the expression of basic fibroblast g rowth factor (bFGF), and two of its high affinity receptors (FGFR1 and FGFR2), were examined in the male rat brain during early postnatal de velopment; the reverse transcription-polymerase chain reaction (RT-PCR ) was used to obtain mRNA measurements which were expressed relative t o mRNA for GAPDH as a constant. In the rat cerebrum, the mRNAs for bFG F and for FGFR2 were relatively low in amount within the first postnat al week, but by 28 days, they were as high as in the 1-year-old rat ce rebrum. In contrast, the expression of FGFR1 was biphasic: mRNA levels were higher at postnatal days 1 and 28 than at day 21. Quantitation o f mRNA from microdissected regions of 28-day-old rat brain revealed th at the expression of bFGF and of FGFR2 showed a marked variation betwe en regions but the expression of FGFR1 appeared less variable between the regions that were analyzed. For all three genes the hippocampus ap peared to have high relative amounts of mRNA. The temporal patterns of expression of bFGE FGFR1 and FGFR2 also differed with brain region du ring early postnatal development. In the occipital cortex and inferior colliculus, the mRNAs for bFGF and FGFR2 both increased in amount dur ing the first month, unlike that for FGFR1. However, in the cerebellum , the highest expression of bFGF and FGFR1 mRNAs occurred at postnatal day 1; FGFR2 expression apparently showed less change with age. The t emporal changes in bFGE FGFR1 and FGFR2 expression in different brain regions during early postnatal development suggest that receptor regul ation may permit different physiological effects of bFGF according to brain region and developmental age.