Effects of omega 3 polyunsaturated fatty acids, antioxidants, and/or non‐steroidal inflammatory drugs in the brain of neonatal rats exposed to intermittent hypoxia

Abstract

Preterm infants experience frequent arterial oxygen desaturations during oxygen therapy, or intermittent hypoxia (IH). Neonatal IH increases oxidative distress which contributes to neuroinflammation and brain injury. We tested the hypotheses that exposure to neonatal IH is detrimental to the immature brain and that early supplementation with antioxidants and/or omega 3 polyunsaturated fatty acids (n‐3 PUFAs) combined with non‐steroidal anti‐inflammatory drugs (NSAIDs) is protective. Newborn rats were exposed to brief hypoxia (12% O2) during hyperoxia (50% O2) from the first day of life (P0) until P14 during which they received daily oral supplementation with antioxidants, namely coenzyme Q10 (CoQ10) or glutathione nanoparticles (nGSH), n‐3 PUFAs and/or topical ocular ketorolac. Placebo controls received daily oral olive oil and topical ocular saline. Room air (RA) littermates remained in 21% O2 from birth to P21 with all treatments identical. At P14 animals were allowed to recover in RA until P21 with no further treatment. Whole brains were harvested for histopathology and morphometric analyses, and assessed for biomarkers of oxidative stress and inflammation, as well as myelin injury. Neonatal IH resulted in higher brain/body weight ratios, an effect that was reversed with n‐3 PUFAs and n‐3 PUFAs+CoQ10 with or without ketorolac. Neonatal IH was also associated with hemorrhage, oxidative stress, and elevations in inflammatory prostanoids. Supplementation with n‐3 PUFAs and nGSH with and without ketorolac were most beneficial for myelin growth and integrity when administered in RA. However, the benefit of n‐3 PUFAs was significantly curtailed in neonatal IH. Neonatal IH during a critical time of brain development causes inflammation and oxidative injury. Loss of therapeutic benefits of n‐3 PUFAs suggest its susceptibility to oxidation in neonatal IH and therefore indicate that co‐administration with antioxidants may be necessary to sustain its efficacy.

Comparing the efficacy in reducing brain injury of different neuroprotective agents following neonatal hypoxia–ischemia in newborn rats: a multi-drug randomized controlled screening trial

“…Omegaven, an Omega-3 triglyceride emulsion, has been shown to be neuroprotective in different preclinical animal models of newborn brain injury 55 . Docosahexaenoic acid (DHA) is one of the major omega-3 polyunsaturated fatty acids and it has been shown to be essential for development and function of the brain.…”

“…Docosahexaenoic acid (DHA) is one of the major omega-3 polyunsaturated fatty acids and it has been shown to be essential for development and function of the brain. It reduces excitotoxicity, inflammation and free radical production following neonatal hypoxic-ischemic brain injury in different animal models 55 . We found that a single dose of Omegaven (0.75 mg/kg) (Table 1 ) administered immediately after hypoxia–ischemia was superior to a repetitive dosing regimen and significantly reduced brain area loss in our standardized model.…”

Early versus late caffeine and/or non‐steroidal anti‐inflammatory drugs (NSAIDS) for prevention of intermittent hypoxia‐induced neuroinflammation in the neonatal rat

“…We utilized a model of neonatal IH developed in our laboratory that consistently produces oxidative stress, as previously reported (Manlapaz‐Mann et al, 2021; Soontarapornchai et al, 2021). In the rat, postnatal day 1–5 is the preterm equivalent of 23–32 weeks human gestation.…”

“…The IH profile consisted of an initial exposure of hyperoxia (50% O 2 ) for 30 minutes followed by three brief, 1‐minute, clustered hypoxic events (12% O 2 ), with a 10‐minute re‐oxygenation in 50% O 2 between each hypoxic event. Recovery from IH occurred in 50% O 2 following each clustered IH event for 2.5 hours for a total of eight clustering IH episodes per day for 14 days, as previously described (Manlapaz‐Mann et al, 2021; Soontarapornchai et al, 2021). Oxygen saturation was confirmed on a sentinel un‐anesthetized rat pup from each group using the MouseOx Pulse Oximeter and WinDaq Waveform Browser software (STARR Life Sciences Corp., Oakmont PA) before and after IH exposure.…”

“…Using our neonatal IH model (Manlapaz‐Mann et al, 2021; Soontarapornchai et al, 2021) we tested the hypothesis that early caffeine and/or NSAIDs confer superior therapeutic benefits for protection against IH‐induced neuroinflammation than late treatment. Our hypothesis was tested with the following objectives: 1) to examine the effects of neonatal IH on inflammation in the neonatal rat brain; 2) to compare the effects of caffeine, ketorolac or ibuprofen, administered individually during neonatal IH, on brain inflammation; 3) to establish whether Caff and/or NSAID co‐treatment has synergistic effects for reducing brain inflammation and apoptosis; 4) to examine whether topical ocular Keto penetrates the brain and has anti‐inflammatory effects; and 5) to investigate whether early treatment during IH exposure is more beneficial than late treatment during recovery/reoxygenation.…”