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

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