NAC +taVNS in IDM Who Are Poor Oral Feeders

N-acetylcysteine Plus Transcutaneous Vagus Nerve Stimulation in Infants of Diabetic Mothers Who Fail Oral Feeding

Infants of diabetic mothers who are failing to learn oral feeding by term age equivalence have greater CNS oxidative stress, which interact to predict poor neuroplasticity response to transcutaneous vagus nerve stimulation paired with oral feeding. We propose treating the oxidative stress in IDM infants prior to initiating taVNS, with an FDA-approved antioxidant (N-acetylcysteine, NAC) to improve CNS oxidative stress, which in turn regulates expression of many genes including BDNF, that may enhance motor learning.

Our group has recently conducted a first-in-infants pilot trial of pairing transcutaneous auricular vagus nerve stimulation (taVNS) with feeding to assist learning oromotor skills. We are enrolling preterm and HIE infants who are failing to learn oral feeds and clinically determined to need a G-tube. In preliminary data, taVNS paired with one or two daily feedings for 2 weeks resulted in 50% of infants attaining full feeds and avoiding G-tube. A notable number of non-responders were infants of diabetic mothers (IDM) exposed to poor glucose control during pregnancy, all of whom required a G-tube. Uncontrolled maternal hyperglycemia is associated with increased systemic and neuro-inflammation, CNS oxidative stress, DNA damage, and worse neonatal outcomes compared to infants of euglycemic mothers. In neonatal animal models, hyperglycemia has been shown to decrease BDNF, alter long-term synaptogenesis and hippocampal neurochemistry, with ongoing CNS oxidative stress and inhibition of the cortical neuronal plasticity required for learning. In our pilot trial of taVNS-paired feeding, CNS glutathione concentrations (GSH), a MR spectroscopy (MRS) marker of oxidative stress, had significant interaction with IDM in predicting outcome, strongly suggesting that ongoing CNS oxidative stress contributes to neuropathology in IDMs failing oral feeding. NAC is an FDA-approved antioxidant that is safe and crosses the blood brain barrier, increasing CNS GSH. NAC reduces CNS oxidative stress, enhances learning and provides a neuroprotective effect after brain injury in our and others neonatal HI and neuroinflammatory animal models. Both GSH and BDNF enhance neuroplasticity. Therefore, we hypothesize that pre-treatment with NAC in IDMs who are failing oral feeding, followed by taVNS-paired feeding, will decrease oxidative stress induced by maternal hyperglycemia and IDM-associated brain injury, and increase response to taVNS-paired feeding rehabilitation.

We will obtain parental consent, and then administer NAC 100mg/kg loading dose, followed by 75mg/kg q 6h via nasogastric tube, started 4 days prior to taVNS-paired feeding and continued for a total of 14 days. We will perform pharmacokinetics of oral NAC, and MRIs prior to, after 3-4 days of NAC, and after taVNS treatment period.

NAC will be given via nasogastric tube (n,g.) 100mg/kg loading dose, then 75mg/kg/dose n.g. q 6h, administered 1h before a feed, for a total of 14 days. taVNS will be administered to left ear during active sucking with 2 daily feedings starting after 4 days of NAC, continuing for 10 days.

[GSH] and other CNS metabolites by MRS before, and after 3-4 days of NAC and after NAC+taVNS treatment

Inclusion Criteria: Infants of diabetic mothers who are failing oral feeding, >39weeks gestation at enrollment, who are clinically stable, on minimal respiratory support (nasal cannula or room air), and clinical team has determined are G-tube candidates Exclusion Criteria: Unstable infants or those requiring positive pressure respiratory support Infants <39 weeks gestation at enrollment Major unrepaired congenital anomalies or anomalies that limit feeding volumes Infants with cardiomyopathy Repeated episodes of autonomic instability (apnea/ bradycardia) not self resolving

Badran BW, Jenkins DD, Cook D, Thompson S, Dancy M, DeVries WH, Mappin G, Summers P, Bikson M, George MS. Transcutaneous Auricular Vagus Nerve Stimulation-Paired Rehabilitation for Oromotor Feeding Problems in Newborns: An Open-Label Pilot Study. Front Hum Neurosci. 2020 Mar 18;14:77. doi: 10.3389/fnhum.2020.00077. eCollection 2020.

Badran BW, Jenkins DD, DeVries WH, Dancy M, Summers PM, Mappin GM, Bernstein H, Bikson M, Coker-Bolt P, George MS. Transcutaneous auricular vagus nerve stimulation (taVNS) for improving oromotor function in newborns. Brain Stimul. 2018 Sep-Oct;11(5):1198-1200. doi: 10.1016/j.brs.2018.06.009. Epub 2018 Jun 30. No abstract available.