Local cold stress to the soles induces retroplacental hemorrhage in rats

The aim of this study was to investigate the effect of local cold stress to the soles on placental histology in rats. Pregnant rats were subjected to a cold provocation (0 degrees C, 12 degrees C) and room temperature (23 degrees C) for 15 and 30 minutes. During cold stimulation and at the control temperature, uterine blood flow and uterine contraction were measured simultaneously. Histological studies of the placentas of these rats were also performed. Cold stress at 0 degrees C and 12 degrees C significantly decreased uterine blood flow (P < .005, P < .02) compared with controls (23 degrees C). The decrease in uterine blood flow was greater at 0 degrees C than at 12 degrees C stress. Cold-induced stress (0 degrees C) also evoked an isometric tension with increased frequency and amplitude in the rat uterus (P < .003, P < .0002) compared with controls (23 degrees C). Stimulation at 12 degrees C did not induce any uterine contractions. Placental histology of rats stressed at 0 degreesC revealed hemorrhages into the decidua basalis. These findings suggest that local cold stress decreases uterine blood flow and increases uterine contraction, resulting in retroplacental hemorrhage in rats. This model may account for human abruptio placentae.