Effect of maternal antibiotic treatment on fetal periventricular white matter cell death in a rabbit intrauterine infection model

AIM

To evaluate the effects of maternal antibiotic treatment on fetal brain cell death in a rabbit intrauterine infection model.

METHODS

After Escherichia coli uterine-horn inoculation in 22 pregnant rabbits, followed at various times by ceftriaxone and caesarean section, cell death in white matter (histology and fragmented DNA staining) from fetuses killed at extraction was compared across groups using the Mantel-Haenszel test and Fisher's exact test for small numbers.

RESULTS

White matter cell death was consistently present at 48 h, with ceftriaxone initiation at 24 h (group 1), detectable at 84 but not 60 h, with ceftriaxone initiation at 12 h, and significantly reduced at 84 h with ceftriaxone initiation at 6 h (60% vs 100% in group 1, p < 0.001, Fisher's exact test).

CONCLUSION

Early maternal antibiotic therapy delays white matter cell death in rabbit fetuses exposed to intrauterine infection. This may provide a window for preventing white matter damage.

Intrauterine infection induces programmed cell death in rabbit periventricular white matter

An association between chorioamnionitis and periventricular leukomalacia has been reported in human preterm infants. However, whether this link is causal has not been convincingly established, and the underlying molecular mechanisms remain unclear. The objective of this study was to establish a reproducible model of cerebral white matter disease in preterm rabbits after intrauterine infection. Escherichia coli was inoculated into both uterine horns of laparotomized pregnant rabbits when gestation was 80% complete. The fetuses were delivered by cesarean section and killed 12, 24, or 48 h after the inoculation. Programmed cell death in the white matter was evaluated by hematoxylin-eosin-saffron staining and in situ fragmented DNA labeling (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling). In a first group of 14 pregnant rabbits not treated with antibiotics, all fetuses delivered 48 h after inoculation were stillborn, whereas fetuses extracted 12 or 24 h after inoculation were alive. No significant cell death was detected in the live fetuses compared with the control noninfected rabbits. In a second group of five pregnant rabbits treated with ceftriaxone initiated 24 h after the inoculation and continued until cesarean section was performed 48 h after inoculation, 13 fetuses were alive, but all showed evidence of extensive programmed cell death in the white matter by hematoxylin-eosin-saffron staining and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling. White matter damage became histologically detectable only 48 h after inoculation. Three of the 13 brains displayed periventricular white matter cysts mimicking human cystic periventricular leukomalacia. The high reproducibility of white matter damage in our model should permit further studies aimed at unraveling the molecular mechanisms of periventricular leukomalacia.