Fig. 3: Maternal obesity (MO) reduces T3 concentration and thyroid hormone signaling, linking to impaired brown adipogenesis with a fetal origin.

a Fetal mass in control and obesity dam (MO) at 22 °C (n = 6). b Density of brown progenitors (solid circle) and preadipocytes (dash circle) in female offspring BAT at P0, 21 days (weaning), and 4 months of age. FACS sorted brown progenitors and preadipocytes in BAT-stromal vascular fractions using brown progenitor marker Lin: CD45−/PDGFRa+ (in black solid circle) and brown preadipocyte marker Lin: EBF2+/PDGFRa+ (dash black circle in right side quarter). c Quantified brown progenitors and preadipocytes in BAT of female offspring (n = 5). Whisker of box plots shows means and individual values from minimum to maximum. d Thyroid hormone (TH) thyroxine (T4) and triiodothyronine (T3) concentrations were analyzed in fetal and neonatal BAT at embryonic days E18.5 (n = 15) and P0 (n = 17). e, f mRNA expression of TH receptors TRα and TRβ (e), and TH responsive genes Ppargc1a and Ucp-1 (f) in fetal and neonatal BAT at E18.5 and P0 (n = 6). mRNA expression was normalized to 18 S rRNA. g Immunoblotting measurements of PGC-1a, UCP-1, and PRDM16 protein contents in fetal (E18.5) and neonatal BAT (n = 6). β-tubulin was used as a loading control. h Immunostaining of mitochondrial (mito-tracker) and UCP-1 protein in neonatal BAT (n = 4). Scale bar 100 µm. i Thermal imaging of female neonates born to control and MO dam (n = 14 in control; n = 11 in MO). Imaging was taken immediately after removing from cages to limit the effects of ambient temperature and heat loss. j Diagram illustrates TH uptake, T3 and T4, from blood circulation and bio-active conversion in brown adipocytes. TH membrane receptor MCP8 for TH uptake in brown adipocytes, TH responsive element (TRE), nuclear TH receptors (THRα and β), iodothyronine deiodinases Dio2 and Dio3, TH downstream thermogenic genes Ucp-1, Ppargc1a. k mRNA expression of Dio2 and Dio3 in fetal and female neonatal BAT at E18 and P0 (n = 6). mRNA expression was normalized to 18 S rRNA. l Protein contents of D2 and D3 were measured by immunoblotting; β-tubulin was used as a loading control (n = 6). For data analyses, each pregnancy (dam) was considered as a replicate unit. Data are presented as mean ± s.e.m. Unpaired Student’s t test with two-tailed distribution was used in data analyses.