Neuroprotective effects of antenatal magnesium sulfate under inflammatory conditions in a Sprague-Dawley pregnant rat model.

OBJECTIVE: Antenatal magnesium sulfate (MgSO4 ) is recommended for fetal neuroprotection. The aim of this animal study was to assess the neuroprotective effect of in utero exposure to MgSO4 , under inflammatory conditions.

METHODS: Timed pregnant Sprague-Dawley (SD) rats (n = 29) received four intra-peritoneal (IP) injections of lipopolysaccharides (LPS; 200 μg/kg), combined with increasing concentrations of MgSO4 (25, 50 or 100 mg/kg, n = 19) or saline solution (SS; n = 10). In the second set of experiments, animals (n = 8) received a single IP injection of i) LPS (500 μg/kg), MgSO4 (50 mg/kg) and SS (n = 4) or ii) LPS (500 μg/kg), MgSO4 (50 mg/kg) and IL-6 (12 μg/kg) (n = 4). Neurodevelopmental outcomes of surviving pups (n = 212) were assessed by the open field and the rotarod tests.

RESULTS: Pups' average weight at postnatal day (P) 25 was 75.77 g and 89.08 g in MgSO4 and control groups, respectively (p = 0.02). Pups in MgSO4 group have traveled a shorter distance and have shown reduced motor balance and coordination (p < 0.01). Average weight of pups receiving (LPS + MgSO4 + IL-6) was 92.26 g at P25, compared to 75.86 g in (LPS + MgSO4 +SS) group (p < 0.05).

CONCLUSIONS: In our model, MgSO4 induces pup's growth retardation and motor deficits, which may partly be related to a lower IL-6 circulating concentration.