Failure to thrive and neonatal lethality in PPARγ^-/F:MORE^+/Cre mice.

<p>(A) PPARγ^-/F:MORE^+/Cre mice (right) show dermal hypopigmentation and an interscapular concavity (thick arrow, right panel) corresponding to the position of the interscapular brown fat pad in normal mice (thick arrow, left panel). Thin arrows designate retinal pigment indicating the paleness of this PPARγ^-/F:MORE^+/Cre neonate is not due to albinism. (B-D) Interscapular adipose tissue was virtually absent in PPARγ^-/F:MORE^+/Cre P3 neonates. The interscapular region contains BAT in control (dashed outline, B), but not in mutant (dashed outline, C) P3 neonates. Occasional mutants retained small amounts of interscapular tissue consisting primarily of white adipose tissue (WAT)-like tissue (dashed outline, D). (E) Body weight of neonatal mice from PPARγ^F/F x PPARγ^<b>+/-</b>:MORE^+/Cre matings. PPARγ^-/F:MORE^+/Cre mice are slightly smaller than littermates at birth (* p < 0.002), subsequently fail to gain weight in spite of apparently normal suckling and the appearance of a milk spot and are markedly smaller than littermates at P3 (*** p = 0.00001). In contrast, littermates gain weight daily (** p < 0.0003 vs. previous day). (F) Organ weights showing selective hepatomegaly in P3 PPARγ^-/F:MORE^+/Cre mice (* p < 0.05; NS, p > 0.05). (G) Neonatal lethality of PPARγ^-/F:MORE^+/Cre mice. The majority of PPARγ^-/F:MORE^+/Cre mice were euthanized at humane endpoints or found dead between P5 and P13 (* p < 0.0001). In E and F “Control” indicates combined results for PPARγ^+/F:MORE^+/+, PPARγ^-/F:MORE^+/+ and PPARγ^+/F:MORE^+/Cre neonates.