Heat stress induces persistent placental dysfubction and fetal growth restriction via the ERS-MAPK-apoptosis axis

Maternal heat stress (HS) is an emerging risk factor for adverse pregnancy outcomes, yet how gestational heat exposure causes persistent placental dysfunction remains unclear. In the present study, we established a murine HS model (38.5{degrees}C, 2.5 h/day, E0-E12.5) followed by thermal recovery to E17.5. HS reduced fetal weight during early gestation and caused persistent fetal growth restriction after recovery, despite partial placental weight restoration. Histological analyses revealed early reductions in the junctional and labyrinth zones, followed by sustained labyrinthine deficiency and compensatory junctional zone expansion. Consistently, HS impaired placental vascularization, with reduced vessel length and area, decreased CD31 and -SMA abundance, and altered angiogenesis-related gene expression. HS also triggered oxidative stress, weakened antioxidant capacity, disrupted anti-inflammatory signaling, reduced tight junction protein expression, and compromised barrier integrity. Mechanistically, HS induced excessive endoplasmic reticulum stress, accompanied by increased CHOP, phosphorylated ERK, and cleaved caspase-3. In conclusion, our data unveil a heat-induced placental insufficiency program that restricts fetal growth through vascular, redox, barrier, and ERS-MAPK-apoptotic remodeling. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC="FIGDIR/small/730306v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@177be8forg.highwire.dtl.DTLVardef@7faa52org.highwire.dtl.DTLVardef@1870971org.highwire.dtl.DTLVardef@7d1705_HPS_FORMAT_FIGEXP M_FIG C_FIG