Fig. 4.

Anxiety-like behavior, CRH, and neuroendocrine functions. (A) On the x axis is indicated the strain of the foster mother. FVB/J fostered Npy1r^rfb mice and C57BL/6J fostered mice, the latter independently of the genotype, showed higher anxiety level in the EPM and OF tests compared with FVB/J fostered Npy1r^2lox mice. Data are the mean ± SEM; n = 12–18 from seven to nine litters. (A Left) Two-way ANOVA revealed a significant effect of genotype, foster mother strain, and genotype–foster mother strain interaction for percent of time in open arms [F_(1,59) = 14.0, P < 0.001; F_(1,59) = 4.03, P < 0.05; F_(1,59) = 26.4, P < 0.001, respectively], and genotype and genotype–foster mother strain interaction for percent of entries in open arms [F_(1,59) = 10.8, P = 0.001; F_(1,59) = 11.7, P < 0.005, respectively]. *P < 0.01 and ^#P < 0.05 versus Npy1r^2lox mice fostered to FVB/J mothers, by Newman–Keuls. (A Right) Two-way ANOVA revealed a significant effect of foster mother strain for percent of time of immobility in the center [F_(1,59) = 4.99, P < 0.05], genotype and foster mother strain for total distance traveled [F_(1,59) = 12.92, P < 0.001; F_(1,59) = 11.67 P < 0.005, respectively]. *P < 0.01 and ^#P < 0.05 versus Npy1r^2lox mice fostered to FVB/J mothers. ^§P = 0.052 versus Npy1r^2lox mice raised by FVB/J mothers, by Newman–Keuls. (B) FVB/J fostered Npy1r^rfb and C57BL/6J fostered mice of either genotype showed a significant increase of serum levels of corticosterone compared with FVB/J fostered Npy1r^2lox mice. Data are the mean ± SEM from three independent experiments (n = 9–15). Two-way ANOVA revealed a significant effect of genotype [F_(1,40) = 7.41, P < 0.05]; genotype–foster mother strain interaction: F_(1,40) = 3.88, P = 0.056. P < 0.05 versus Npy1r^2lox mice fostered to FVB/J mothers, by Newman-Keuls. (C) FVB/J fostered Npy1r^rfb mice and C57BL/6J fostered mice of either genotype showed increased density of CRH immunoreactive cell bodies and of NPY immunoreactive fibers in the medial parvocellular division of the paraventricular nuclei (PVNmp). Data are expressed as the mean fractional area ± SEM (n = 5–7 from three litters). (Scale bar: 50 μm; Inset, 25 μm.) CRH: Two-way ANOVA revealed a significant effect of genotype–foster mother interaction [F_(12,20) = 5.9, P < 0.05]. *P < 0.05 versus Npy1r^2lox mice fostered to FVB/J mothers by Newman–Keuls. NPY: *P < 0.05 by Student's t test. (D) FVB/J fostered Npy1r^rfb mice and C57BL/6J fostered mice of either genotype showed decreased density of CRH immunoreactive fibers in the CeA. Data are expressed as the mean fractional area ± SEM (n = 5–7 from three litters). Two-way ANOVA revealed a significant effect of genotype and of genotype–foster mother strain interaction [F_(1,21) = 12.0, P < 0.005; F_(1,21) = 8.84, P = 0.01, respectively]. *P < 0.01 versus Npy1r^2lox mice fostered to FVB/J mothers by Newman–Keuls. (Scale bar: 50 μm.)