Corticotropin releasing factor mRNA and peptide levels are differentially regulated in the developing ovine brain

The regulation of CRF mRNA and protein in the developing ovine brain has been studied to assess the hypothesis that CRF is differentially regulated in the hypothalamus (Hypo), hippocampal-amygdala complex (H & A), frontal cerebral cortex (FCC) and brainstem (BS). We used a quantitative RNase protection assay and radioimmunoassay to determine mRNA and peptide concentrations, respectively, from the last third of gestation until term (i.e., from 95 to 142 days gestation (dg); term approximately 145 days). The major findings from this study are: (1) Hypothalamic CRF mRNA was increased by 2-fold in 140-142 dg fetuses compared to 128-138 and 95-123 dg fetuses; P = 0.016. (2) In the hypothalamus of 140-142 dg fetuses, there was a 2.5-fold increase in CRF mRNA derived from polyadenylation at poly(A) sites 2, 3 or 4; P = 0.005. (3) In 128-138 dg fetuses, CRF mRNA in the frontal cortex was 2-fold higher than in the other brain regions during this time period; P = 0.008. (4) CRF peptide concentrations in the Hypo were 2.5-fold higher in 140-142 dg fetuses compared to 95-106 and 128-138 dg fetuses; P = 0.007. (5) CRF peptide concentrations in the frontal cortex were 5.5-fold higher in 140-142 dg fetuses compared to fetuses at 95-106 dg; P = 0.004. (6) CRF peptide concentrations in the H & A were 5-fold higher in 140-142 dg fetuses compared to 95-106 dg fetuses; P = 0.029. The results from the present study demonstrate for the first time that CRF mRNA and peptide are differentially regulated in a region-specific manner during development.