Vitamin D insufficiency in neonatal hypoxic-ischemic encephalopathy

Neonatal encephalopathy: a systematic review of reported treatment outcomes

BACKGROUND

Neonatal encephalopathy (NE) is a multi-organ condition potentially leading to death or long-term neurodisability. Therapeutic hypothermia is the standard treatment for NE; however, long-term impairments remain common. Studies of new treatments for NE often measure and report different outcomes. Core outcome sets (COSs), a minimum set of outcomes to be measured and reported in all studies for a condition, address this problem. This paper aimed to identify outcomes reported (primary, secondary, adverse events and other reported outcomes) in (1) randomised trials and (2) systematic reviews of randomised trials of interventions for the treatment of NE in the process of developing a COS for interventions for the treatment of NE.

METHODS

We completed a systematic search for outcomes used to evaluate treatments for NE using MEDLINE, Embase, Cochrane CENTRAL, the Cochrane Database of Systematic Reviews and the WHO International Clinical Trials Registry Platform. Two reviewers screened all included articles independently. Outcomes were extracted verbatim, similar outcomes were grouped and outcome domains were developed.

RESULTS

386 outcomes were reported in 116 papers, from 85 studies. Outcomes were categorised into 18 domains. No outcome was reported by all studies, a single study reported 11 outcomes and it was not explicitly stated that outcomes had input from parents.

DISCUSSION

Heterogeneity in reported outcomes means that synthesis of studies evaluating new treatments for NE remains difficult. A COS, that includes parental/family input, is needed to ensure consistency in measuring and reporting outcomes, and to enable comparison of randomised trials.

Serum Vitamin D status in full term neonates with severe perinatal depression

BACKGROUND

Severe perinatal depression is a significant cause of mortality and morbidity in neonates. Vitamin D levels were observed to be low in mothers and their neonates with hypoxic ischemic encephalopathy in some studies, owing to its neuroprotective properties.

OBJECTIVE

Primary objective was to compare vitamin D deficiency state in full term neonates with severe perinatal depression and healthy term controls. Secondary objectives were to determine sensitivity and specificity of serum 25(OH)D<12 ng/mL in predicting mortality, development of hypoxic ischemic encephalopathy, abnormal neurological examination at discharge, and developmental outcome at 12 weeks of age.

MATERIAL AND METHODS

Serum 25(OH)D levels in full term neonates with severe perinatal depression and healthy controls were compared.

RESULTS

Serum 25(OH)D levels in severe perinatal depression and controls (n = 55 each group) were significantly different (7.50 ± 3.53 ng/mL vs 20.23 ± 12.70 ng/mL). At cut-off of <  12 ng/mL, serum 25(OH)D could predict mortality with 100% sensitivity and 17% specificity and poor developmental outcomes with sensitivity of 100% and specificity of 50% .

CONCLUSION

Vitamin D deficiency status at birth can serve as an effective screening tool and poor prognostic markers in term neonates with severe perinatal depression.

Correlation analysis of NT-proBNP (N-terminal probrain natriuretic peptide), 25-Hydroxyvitamin D, HMGB1(High-mobility group box 1), ACTA (endogenous activin A), blood glucose level, and electrolyte level with developmental quotient scores in neonates with hypoxic-ischemic encephalopathy

BACKGROUND

To investigate the correlation between N-terminal probrain natriuretic peptide (NT-proBNP), 25-hydroxyvitamin D (25-(OH) D), high-mobility group box 1(HMGB1), endogenous activin A (ACTA), blood glucose level, electrolyte levels and developmental quotient (DQ) scores of Hypoxic-ischemic encephalopathy (HIE).

METHODS

In this retrospective study, a total of 90 neonates diagnosed with HIE who were admitted to our hospital from January 2018 to June 2021 were retrospectively enrolled, and 40 healthy full-term neonates born in our hospital during the same period were randomly selected. Neonates with HIE and healthy conditions were set as the study group and control group, respectively. Neonates with HIE are divided into three subgroups, mild, moderate, and severe, based on the severity of HIE. The Gesell Developmental Scale (GDS) was used to assess neural development of neonates at 9 to 12 months postnatal. Biomarkers of peripheral venous blood were measured and collected in all neonates, including NT-proBNP, (25-(OH) D), HMGB1, ACTA, electrolyte levels and blood glucose levels. General demographic information and Apgar score were compared between the two groups. The differences between the two groups of biomarkers were compared and the correlation between these biomarkers and DQ scores was evaluated.

RESULTS

There was no significant difference in gestational age, maternal age, gender, way of birth, birth weight, gestational age and whether the mother was a primipara between the two groups (P>0.05). The 10 min Apgar score of the study group (5.87±0.36) was lower than that of the control group (9.37±0.32) with significant difference (P<0.05). The levels of NT-proBNP, HMGB1, and ACTA in the study group were higher than that in the control group (243.87±21.29 pmol/L vs. 116.98±22.19 pmol/L; 8.92±1.87 μg/L vs. 3.28±1.08 μg/L; 23.78±0.89 ng/ml vs. 2.98±0.38 ng/ml), while the levels of 25-(OH) D and electrolyte levels were lower than that in the control group (24.28±1.87 vs. 31.29±1.93; K+: 4.49±0.23 mmol/L vs. 4.73±0.21 mmol/L; Na+: 118.76±13.02 mmol/L vs. 134.28±12.29 mmol/L; Ca2+: 1.77±0.23 mmol/L vs. 2.35±0.26 mmol/L; Mg2+: 0.61±0.17 mmol/L vs. 0.91±0.17 mmol/L), with statistically significant differences (P<0.001). The levels of NT-probNP, HMGB1, ACTA and the incidence of hypoglycemia were the highest in the severe group, which were significantly higher than those in the moderate group and mild group (P<0.05). The levels of NT-probNP, HMGB1, ACTA and the incidence of hypoglycemia were the lowest in the mild group. The 25-(OH) D level, the incidence of hyperglycemia and electrolyte levels were the lowest in the severe group, which were significantly lower than those in the moderate and mild groups (all P<0.05). Meanwhile, the 25-(OH) D level, the incidence of hyperglycemia and electrolyte levels in the moderate group were lower than those in the mild group, and the differences were statistically significant (all P<0.05). The incidence of hyperglycemia in severe group (16 cases) was the lowest, significantly lower than that in moderate group (17 cases) and mild group (22 cases), and the difference was statistically significant (all P<0.05). The DQ scores of HIE neonates were negatively correlated with NT-proBNP, HMGB1, and ACTA (r=-0.671, -0.421, -0.518, all P< 0.001). The DQ scores was positively correlated with levels of 25-(OH) D and blood glucose level (r =0.621, 0.802, all P< 0.001). The DQ scores was also positively correlated with levels of potassium, sodium, calcium and magnesium (0.367, 0.782, 0.218, 0.678, all P<0.001).

CONCLUSION

The NT-proBNP, HMGB1, ACTA, 25-(OH) D, blood glucose levels and electrolyte levels are correlated with the severity of HIE, and developmental quotient scores in neonates with HIE. These biomarkers are suggestive for assessing the prognosis of neonate with HIE.

Vitamin D suppresses ferroptosis and protects against neonatal hypoxic-ischemic encephalopathy by activating the Nrf2/HO-1 pathway

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is a major cause of neonatal death, and vitamin D (VD) is a neuroprotection nutrition whose deficiency is associated with its risk. However, the mechanism of VD involved in neonatal HIE is not well known.

METHODS

In this experiment a hypoxic-ischemic brain damage (HIBD) model was established by using the Rice-Vannucci method, rats were intraperitoneally injected with 0.1 µg/kg VD every day for two weeks. The brain damage and mitochondria injury were examined by hematoxylin-eosin (HE) staining and transmission electron microscope (TEM), respectively. The oxidation response and inflammatory factors were determined by enzyme-linked immunosorbent assay (ELISA), and the cell viability was determined by Cell Counting Kit-8 (CCK-8). mRNA and protein expression were detected by quantitative real real-time PCR (qRT-PCR), Western blot, and immunofluorescence.

RESULTS

The results showed VD effectively ameliorated brain histologic damage and mitochondria injury induced by hypoxic ischemia (HI). VD elevated the expression of Nrf2 and HO-1, which resulted in increased levels of GPX4, superoxide dismutase (SOD), and glutathione (GSH) and reduced content of malondialdehyde (MDA) and reactive oxygen species (ROS), resulting in decreased ferroptosis in HI-treated rats. Moreover, VD reduced the secretion of inflammatory factors, tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β.

CONCLUSIONS

VD suppresses ferroptosis through activation of the Nrf2/HO-1 signaling pathway and exerts a protective role in neonatal HIE.

The role of lymphocytes in neonatal encephalopathy

Neonatal encephalopathy is a syndrome characterised by abnormal neurological function often caused by a hypoxic insult during childbirth. Triggers such as hypoxia-ischaemia result in the release of cytokines and chemokines inducing the infiltration of neutrophils, natural killer cells, B cells, T cells and innate T cells into the brain. However, the role of these cells in the development of the brain injury is poorly understood. We review the mechanisms by which lymphocytes contribute to brain damage in NE. NK, T and innate T cells release proinflammatory cytokines contributing to the neurodegeneration in the secondary and tertiary phase of injury, whereas B cells and regulatory T cells produce IL-10 protecting the brain in NE. Targeting lymphocytes may have therapeutic potential in the treatment of NE in terms of management of inflammation and brain damage, particularly in the tertiary or persistent phases.

NAC and Vitamin D Improve CNS and Plasma Oxidative Stress in Neonatal HIE and Are Associated with Favorable Long-Term Outcomes

N-acetylcysteine (NAC) and vitamin D provide effective neuroprotection in animal models of severe or inflammation-sensitized hypoxic ischemic encephalopathy (HIE). To translate these FDA-approved drugs to HIE neonates, we conducted an early phase, open-label trial of 10 days of NAC (25, 40 mg/kg q12h) + 1,25(OH)2D (calcitriol 0.05 mg/kg q12h, 0.03 mg/kg q24h), (NVD), for pharmacokinetic (PK) estimates during therapeutic hypothermia and normothermia. We paired PK samples with pharmacodynamic (PD) targets of plasma isoprostanoids, CNS glutathione (GSH) and total creatine (tCr) by serial MRS in basal ganglia (BG) before and after NVD infusion at five days. Infants had moderate (n = 14) or severe HIE (n = 16), funisitis (32%), and vitamin D deficiency (75%). NVD resulted in rapid, dose-responsive increases in CNS GSH and tCr that correlated positively with plasma [NAC], inversely with plasma isofurans, and was greater in infants with lower baseline [GSH] and [tCr], suggesting increases in these PD markers were titrated by neural demand. Hypothermia and normothermia altered NAC PK estimates. NVD was well tolerated. Excluding genetic syndromes (2), prolonged ECMO (2), lost-to-follow-up (1) and SIDS death (1), 24 NVD treated HIE infants have no evidence of cerebral palsy, autism or cognitive delay at 24-48 months. These data confirm that low, safe doses of NVD in HIE neonates decreased oxidative stress in plasma and CNS, improved CNS energetics, and are associated with favorable developmental outcomes at two to four years.

Efficacy of different treatment times of mild cerebral hypothermia on oxidative factors and neuroprotective effects in neonatal patients with moderate/severe hypoxic-ischemic encephalopathy

Objective

To investigate the efficacy of different treatment times of mild cerebral hypothermia for treating moderate/severe hypoxic–ischemic encephalopathy (HIE) in neonatal patients and its effects on oxidative factors.

Methods

This prospective, randomized, controlled study included 92 neonatal patients with moderate/severe HIE and 30 controls. The patients with HIE received routine treatment, 48 hours of hypothermia, or 72 hours of hypothermia.

Results

Superoxide dismutase (SOD) values were significantly lower and malondialdehyde (MDA) and neuron-specific enolase (NSE) values were higher in patients with HIE than in controls before the study. After 24, 48, and 72 hours of treatment, SOD values in all patients with HIE gradually increased and MDA and NSE values gradually decreased. At 3, 7, and 10 days, the Neonatal Behavioral Neurological Assessment scores were highest in the mild hypothermia for 72 hours group than in the other groups. The Mental and Psychomotor Development Indices scores of the Bayley Scales were significantly higher in the mild hypothermia for 72 hours group than in the other groups.

Conclusion

Hypothermia treatment of 72 hours is better than 48 hours for improving oxidative conditions, reducing NSE values, and improving neurological behavior and development for neonates with moderate/severe HIE.

NAC and Vitamin D Restore CNS Glutathione in Endotoxin-Sensitized Neonatal Hypoxic-Ischemic Rats

Therapeutic hypothermia does not improve outcomes in neonatal hypoxia ischemia (HI) complicated by perinatal infection, due to well-described, pre-existing oxidative stress and neuroinflammation that shorten the therapeutic window. For effective neuroprotection post-injury, we must first define and then target CNS metabolomic changes immediately after endotoxin-sensitized HI (LPS-HI). We hypothesized that LPS-HI would acutely deplete reduced glutathione (GSH), indicating overwhelming oxidative stress in spite of hypothermia treatment in neonatal rats. Post-natal day 7 rats were randomized to sham ligation, or severe LPS-HI (0.5 mg/kg 4 h before right carotid artery ligation, 90 min 8% O2), followed by hypothermia alone or with N-acetylcysteine (25 mg/kg) and vitamin D (1,25(OH)2D3, 0.05 μg/kg) (NVD). We quantified in vivo CNS metabolites by serial 7T MR Spectroscopy before, immediately after LPS-HI, and after treatment, along with terminal plasma drug concentrations. GSH was significantly decreased in all LPS-HI rats compared with baseline and sham controls. Two hours of hypothermia alone did not improve GSH and allowed glutamate + glutamine (GLX) to increase. Within 1 h of administration, NVD increased GSH close to baseline and suppressed GLX. The combination of NVD with hypothermia rapidly improved cellular redox status after LPS-HI, potentially inhibiting important secondary injury cascades and allowing more time for hypothermic neuroprotection.

Vitamin D Attenuates Hypoxia-Induced Injury in Rat Primary Neuron Cells through Downregulation of the Dual Oxidase 1 (DUOX1) Gene

BACKGROUND This study aimed to investigate the mechanisms underlying the neuroprotective effects of vitamin D. MATERIAL AND METHODS Rat primary neuron cells were incubated under a hypoxia condition [a hypoxic chamber mixed with anaerobic gas (90% N₂, 5% CO₂) and 5% O₂] to induce cell injury. Cell transfection was performed to overexpress or suppress the expression of dual oxidase 1 (DUOX1). The malondialdehyde (MDA) and superoxide dismutase (SOD) levels were detected using a MDA (A003-2) or SOD (A001-1) kit. DUOX1 mRNA levels were detected using RT-PCR. Hypoxia-inducible factor-1alpha (HIF-1alpha), DUOX1, vitamin D receptor (VDR), NF-kappaB protein expressions were determined by western blotting. Cell apoptosis and reactive oxygen species (ROS) were evaluated by flow cytometry. RESULTS ROS increased significantly after hypoxic treatment. The expressions of HIF-1alpha and DUOX1 were significantly increased after hypoxic treatment. Vitamin D could decrease ROS level, apoptotic neuron cells and DUOX1 expression, and increase VDR expression. Downregulation of DUOX1 significantly decreased MDA level and apoptotic percentages of neuron cells, increased SOD level, and counteracted the hypoxia-induced increase of NF-kappaB signal. Further study showed that overexpression of DUOX1 significantly increased MDA level, ROS level, apoptotic percentages of neuron cells, and NF-kappaB nuclear signaling, while decreased SOD level. Vitamin D significantly counteracted the effects of DUOX1 overexpression induced injury in rat primary neuron cells. CONCLUSIONS Our study indicated that vitamin D may protect neuron cells from hypoxia-induced injury by regulating DUOX1 via the NF-kappaB signaling pathway.

Vitamin D and Stroke: Effects on Incidence, Severity, and Outcome and the Potential Benefits of Supplementation

Vitamin D serum level has been positively associated with improved cardiovascular health, especially with reduction of stroke risk. This systemic review summarizes and synthesizes findings from studies relevant to the relationship between vitamin D and stroke risk, severity, and outcome; potential mechanisms explaining such a relationship; and outcomes from vitamin D supplementation. The literature shows that vitamin D deficiency is a significant risk factor for ischemic stroke, with sun exposure, sex, age, race, diabetes, and genetics playing a role as well. Stroke severity and short- and long-term outcomes also worsen with vitamin D deficiency. The neuroprotective mechanisms by which vitamin D operates to mitigate stroke onset and outcomes have yet to be fully studied, but researchers have proposed several pathways, including promotion of certain neuroprotective growth factors, reduction of arterial pressure through vasodilation, and inhibition of reactive oxygen species. There is some evidence that vitamin D supplementation could lower stroke risk and improve recovery, though outcomes can also be negligible or negative. Although results are mixed and the limitations of vitamin D supplementation merit some caution, vitamin D overall plays a significant role in stroke health. Future research should further develop understanding of the neuroprotective mechanisms of vitamin D and study how supplementation could be administered effectively in stroke treatment.

Clinical features of vitamin D deficiency in children: A retrospective analysis

Vitamin D is very important for children's health. Previous studies have shown that vitamin D deficiency leads to a series of diseases in adults. However, pediatricians are mostly aware of rickets caused by vitamin D deficiency in children and poorly aware of other symptoms. This study aimed to retrospectively analyze the different clinical features of vitamin D deficiency to enhance identification by pediatricians, thus minimizing misdiagnosis. In this study, we retrospectively analyzed the clinical features of vitamin D deficiency in 268 children aged 0-14 years from June 2016 to May 2018 in the Third Affiliated Hospital of Zhengzhou University. Serum 25-hydroxy vitamin D [25(OH)D] levels were determined using the chemiluminescence method. Of the 268 cases, 101 cases showed movement disorder (37.7%) and 167 nervous system abnormalities (62.3%). Among all cases, 6 were misdiagnosed as febrile seizures (2.23%), 5 as epilepsy (1.86%), 2 as Tourette syndrome (0.74%), and 2 as developmental retardation (0.74%). There were significant differences in patients with clinical characteristics of movement disorder and nervous system abnormalities partly between Pre-and post-vitamin D treatment. This analysis revealed that vitamin D deficiency occurs not only in children but also in adolescents, with diverse clinical features. Therefore, pediatricians should pay more attention to clinical different signs and symptoms, and future studies should be conducted to confirm the mechanisms of these processes.

Vitamin D as an Adjuvant Therapy in Neonatal Hypoxia: Is it Beneficial?

Background

Neonatal hypoxic ischemic encephalopathy (HIE) is a potentially devastating disorder associated with significant mortality and long-term morbidity.

Objective

The aim of this study was to study the role of vitamin D as an adjuvant therapy for management of neonatal HIE.

Patients and Methods

This study was carried out on 60 neonates with HIE grade II who were diagnosed according to modified Sarnat staging and were divided in to 2 groups: Group I: Included 30 neonates with Sarnat grade II HIE who received single daily oral dose of vitamin D3 (1000 IU) for 2 weeks in addition to daily subcutaneous (SC) human recombinant erythropoietin (2500 IU/kg) for 5 days and IM or IV magnesium sulphate 250 mg/kg within half an hour of birth, and subsequently 125 mg/kg at 24 and 48 hours of life. Group II: Included 30 neonates with HIE grade II who received erythropoietin and magnesium sulphate as group I but without vitamin D. Two blood samples were taken from all neonates included in both groups; the 1^st at diagnosis and the 2^nd after 2 weeks of therapy. This study included also 30 healthy neonates as a control group. All neonates included in this study were subjected to: complete clinical examination with assessment of Apgar score at 5 and 10 minutes, measurement of arterial blood gases and serum 25 (OH) vitamin D, calcium, phosphorus, S100-B and IL-17 levels.

Results

Before therapy, there were no significant differences between group I and II in PH, PO2 and PCO2 (p= 0.294, 0.462, 0.758 respectively), but after 2 weeks of therapy, there were significantly higher PH levels in group I compared with group II (p <0.001) while there were no significant differences between group I and II regarding PO2 and PCO2. Before therapy, there were no significant differences in serum 25(OH) vitamin D levels between group I and II while there were significantly lower serum 25(OH) vitamin D levels in group I and II compared with controls (P1; comparison between group I and II = 0.742, P2; comparison between group I and controls = 0.001 and P3; comparison between group II and controls = 0. 001). There were no significant differences between group I and II and between group I and II and control as regard serum calcium (P1= 0.943, P2= 0.875 and P3= 0.764) and phosphorus (P1= 0.862, P2= 0.921, P3= 0.786). There were no significant differences between group I and II regarding serum IL-17 levels while there were significantly lower serum IL-17 levels in group I and II compared with controls (P1 = 0.457, P2 = 0.043 and P3 = 0.023). Before therapy, there were no significant differences in serum S100-B levels between group I and II while there were significantly higher serum S100-B levels in group I and II compared with control (P1 = 0.381, P2 = 0.001 and P3= 0.001) but after therapy, there were significantly higher S100-B levels in group II compared with group I and significantly higher S100-B levels in group I and II compared with control (P1= 0.001, P2= 0.043, P3 = 0.001). There were significant negative correlations in group I between serum S100-B and PH and between S100-B and serum vitamin D before and after therapy.

Conclusion

Vitamin D was found to improve the cases of group I as demonstrated by the reduction of serum S100-B levels after vitamin D therapy.

Recommendations

Extensive multicenter studies are required on a large number of patients with Sarnat grade II HIE with longer duration of follow up to give valid recommendations about the use of vitamin D as an adjuvant therapy in Sarnat grade II HIE.

Serum calcium derangements in neonates with moderate to severe hypoxic ischemic encephalopathy and the impact of therapeutic hypothermia: a cohort study

Background: Perinatal hypoxia is a recognized cause of hypocalcemia in neonates in the first 3 days of life. Therapeutic hypothermia (TH) promotes neuroprotection by decreasing calcium influx into the cells during the reperfusion phase thereby increase serum calcium levels. This study examines the trends of serum calcium levels in neonates with hypoxic ischemic encephalopathy (HIE) and the effect of TH.Material and methods: A retrospective cohort study of neonates with moderate to severe HIE admitted to level III neonatal intensive care units (NICU's) in Calgary between September 2011 and October 2015. HIE was staged using modified Sarnat scoring system. Ionized calcium levels were followed in the first 3 days of age.Results: One hundred thirteen neonates admitted with the diagnosis of moderate to severe HIE were included; 89 (79%) underwent TH. Hypercalcemia was significantly higher with TH 57 (64%) compared to 8 (33%) in noncooled group (p = .007). Hypocalcemia was less in TH group; 11 (12%) compared to 5 (21%) in non TH group. Hypo/hypercarbia did not alter the serum calcium levels. Furthermore; there was no increase in the incidence of intracranial hemorrhage, clinical or electrographic seizures, antiepileptic drug use, or hypoxic/ischemic MRI changes with calcium derangements.Conclusion: The incidence of hypocalcemia was reduced by almost half and hypercalcemia was significantly increased with TH in the first 3 days of life. The reduction in hypocalcemia and the increase in hypercalcemia may be attributed to the neuroprotective effect of TH.

Vitamin D and Its Role in Neonatal Hypoxic-Ischemic Brain Injury

Emerging evidence has demonstrated that vitamin D plays an important role in many adult neurologic disorders, but is also critical in neuronal development and pruning in the neonatal and pediatric populations. Neonates are at a particularly high risk of vitamin D deficiency, in part due to the high prevalence of maternal deficiency during pregnancy. Several preclinical studies have demonstrated that infants born to vitamin D-deficient mothers are at a high risk of developing neonatal brain injury, and recent clinical studies have shown that neonates with hypoxic-ischemic encephalopathy (HIE) tend to be vitamin D-deficient. There are limited data, however, on whether additional prenatal or postnatal supplementation may alter the prevalence or severity of neonatal HIE. This review examines the current data supporting the neuroprotective role of vitamin D, with a focus on how these findings may be translated to neonates with HIE.

Vitamin D improves functional outcomes in neonatal hypoxic ischemic male rats treated with N-acetylcysteine and hypothermia

Hypothermia treatment neuroprotects approximately 50% of neonates who present with moderate to severe hypoxic ischemic encephalopathy (HIE). N-acetylcysteine (NAC), a potent antioxidant, is neuroprotective in combination with hypothermia in neonatal hypoxia-ischemia (HI) female rats, but less protective in males. Vitamin D is a neurosteroid, which may provide immunomodulation and improve outcomes for both sexes. We investigated the efficacy of this combination of drugs with hypothermia after severe HI, as well as potential mechanisms of vitamin D effects in the transition to chronic inflammation. DOL 7 rats were randomized to sham, or HI and hypothermia treated with either saline (HYPO), NAC (50 mg/kg/d, HNAC), or HNAC plus 1,25-dihydroxy-vitamin D₃ (0.1 μg/kg/d, HNAC + VitD) daily for 2 weeks. A second set of animals were randomized and treated for 11 days to investigate vitamin D metabolism and inflammatory mediators. Rats treated with HNAC + VitD performed significantly better on tests of strength and use of affected limb, adaptive sensorimotor skills, motor sequence learning, and working memory than either HYPO or HNAC, particularly benefiting male rats. Significantly fewer rats in the HNAC + VitD group had severe hemispheric volume loss. HI injury decreased serum vitamin D at 11 days and induced the enzyme that deactivates vitamin D in the hippocampus, particularly in males. Persistent vitamin D dysregulation was seen in both hippocampi in males, which was not reversed by hypothermia. Vitamin D in combination with hypothermia and NAC supports functional recovery in both sexes of neonatal rats significantly better than hypothermia alone or hypothermia and NAC in this severe HI model.