Ibuprofen Does Not Prevent Inhibition of Fetal Breathing Movements Caused by Intrauterine Inflammation in Fetal Sheep

Antenatal inflammation/infection is a major cause of neonatal apnoea and hypoventilation. Prostaglandin E2 (PGE₂) is a key inflammatory mediator associated with depression of fetal and neonatal breathing. We aimed to determine whether antenatal ibuprofen, a cyclooxygenase inhibitor that reduces synthesis of PGE₂, restores fetal breathing movements (FBM) in late-gestation fetal sheep exposed to systemic lipopolysaccharide (LPS). Fetal sheep (125 days gestation, d; term ~148 d) were instrumentally monitored for continuous measurement of FBM and physiological parameters. At 130 d fetuses were randomly allocated between groups receiving i.v. saline (CTL_SAL, n = 9), escalating doses of LPS (i.v.) over 3 days (LPS_SAL, n = 8), or ibuprofen one hour after each LPS dose (LPS_IBU, n = 8). Regular plasma samples were collected for PGE₂ assessment. At 135 d, cerebrospinal fluid and brainstem tissue were collected at autopsy for assessments of PGE₂ expression, and immunohistochemical quantification of astrocytes and microglia within key brainstem respiratory centres was performed to assess inflammation. LPS exposure increased PGE₂ levels in plasma, cerebrospinal fluid and the RTN/pFRG (p < 0.05) and decreased the incidence, amplitude and amount of the accentuated (>5 mmHg) FBMs. Ibuprofen reduced plasma and RTN/pFRG PGE₂ expression (p < 0.01 and p = 0.031, respectively) but did not restore FBMs. Astrocyte and microglial density increased in the RTN/pFRG, NTS and raphe nucleus in LPS_IBU fetuses, compared to LPS_SAL (p < 0.05). Antenatal ibuprofen treatment did not restore depressed FBM, despite reducing the circulating and brainstem PGE₂ levels in LPS-exposed fetal sheep. Other inflammatory pathways or more specific targeting of PGE₂ may be more effective in preventing apnoea caused by exposure to intrauterine infection/inflammation.