Fig. 4. Survival of sympathetic neurons in absence of CREB. Immunohistochemistry with an antibody recognizing activated caspase-3 (brown) is used to analyze survival of sympathetic neurons in the SCG at E17.5, and anti-TH antibody (blue) is used to identify the region of interest in controls (A,D), Creb^-/- (B,E) and Creb^DBHCre; Crem^-/- mutants (C,F). Representative sections are shown in A-F. Red arrows indicate examples of activated caspase-3-positive cells. (G) Quantitative analysis of apoptotic cells reveals reduced levels of apoptosis in sympathetic neurons of Creb^DBHCre; Crem^-/- mutants (abbreviated as M) at E17.5 in comparison with controls (abbreviated as C). At postnatal stages P0/P2 the level of apoptosis is reduced in control pups and does not change in Creb^DBHCre; Crem^-/- mutants. (H) The size of the SCG in Creb^DBHCre; Crem^-/- mutants is similar between controls and mutants at E17.5. At P0/P2 the size of the SCG in Creb^DBHCre; Crem^-/- mutants is significantly larger than in controls. The mean±s.e.m. for both SCG in at least four to five mice of each genotype are shown. Values are considered significantly different with ^*P<0.05 and ^***P<0.001 compared with controls. Scale bar: 250 µm in A-C; 40 µm in D-F. Asterisk indicates the inner ear.