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Repeated antenatal corticosteroid treatments adversely affect neural transmission time and auditory thresholds in laboratory rats.

ABSTRACT: Antenatal corticosteroid (AC) treatment is given to pregnant women at risk for preterm birth to reduce infant morbidity and mortality by enhancing lung and brain maturation. However, there is no accepted regimen on how frequently AC treatments should be given and some studies found that repeated AC treatments can cause growth retardation and brain damage. Our goal was to assess the dose-dependent effects of repeated AC treatment and estimate the critical number of AC courses to cause harmful effects on the auditory brainstem response (ABR), a sensitive measure of brain development, neural transmission and hearing loss. We hypothesized that repeated AC treatment would have harmful effects on the offspring's ABRs and growth only if more than 3 AC treatment courses were given. To test this hypothesis, pregnant Wistar rats were given either a high regimen of AC (HAC), a moderate regimen (MAC), a low regimen (LAC), or saline (SAL). An untreated control (CON) group was also used. Simulating the clinical condition, the HAC dams received 0.2mg/kg Betamethasone (IM) twice daily for 6 days during gestation days (GD) 17-22. The MAC dams received 3 days of AC treatment followed by 3 days of saline treatment on GD 17-19 and GD 20-22, respectively. The LAC dams received 1 day of AC treatment followed by 5 days of saline treatment on GD 17 and GD 18-22, respectively. The SAL dams received 6 days of saline treatment from GD 17 to 22 (twice daily, isovolumetric to the HAC injections, IM). The offspring were ABR-tested on postnatal day 24. Results indicated that the ABR's P4 latencies (neural transmission time) were significantly prolonged (worse) in the HAC pups and that ABR's thresholds were significantly elevated (worse) in the HAC and MAC pups when compared to the CON pups. The HAC and MAC pups were also growth retarded and had higher postnatal mortality than the CON pups. The SAL and LAC pups showed little or no adverse effects. In conclusion, repeated AC treatment had harmful effects on the rat offspring's ABRs, postnatal growth and survival. The prolonged ABR latencies reflect slowed neural transmission times along the auditory nerve and brainstem auditory pathway. The elevated ABR thresholds reflect hearing deficits. We concluded that repeated AC treatment can have harmful neurological, sensory and developmental effects on the rat offspring. These effects should be considered when weighing the benefits and risks of repeated AC treatment and when monitoring and managing the prenatally exposed child for possible adverse effects.

SUBMITTER: Church MW

PROVIDER: S-EPMC3268869 | biostudies-other | 2012 Jan-Feb

REPOSITORIES: biostudies-other

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Repeated antenatal corticosteroid treatments adversely affect neural transmission time and auditory thresholds in laboratory rats.

Church M W MW Adams B R BR Anumba J I JI Jackson D A DA Kruger M L ML Jen K-L C KL

Neurotoxicology and teratology 20110922 1

Antenatal corticosteroid (AC) treatment is given to pregnant women at risk for preterm birth to reduce infant morbidity and mortality by enhancing lung and brain maturation. However, there is no accepted regimen on how frequently AC treatments should be given and some studies found that repeated AC treatments can cause growth retardation and brain damage. Our goal was to assess the dose-dependent effects of repeated AC treatment and estimate the critical number of AC courses to cause harmful eff ...[more]

PMID: 21963399

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Project description:OBJECTIVE:To describe discordance in antenatal corticosteroid use and resuscitation following extremely preterm birth and its relationship with infant survival and neurodevelopment. STUDY DESIGN:A multicenter cohort study of 4858 infants 22-26 weeks of gestation born 2006-2011 at 24 US hospitals participating in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network, with follow-up through 2013. Survival and neurodevelopmental outcomes were available at 18-22 months of corrected age for 4576 (94.2%) infants. We described antenatal interventions, resuscitation, and infant outcomes. We modeled the effect on infant outcomes of each hospital increasing antenatal corticosteroid exposure for resuscitated infants born at 22-24 weeks of gestation to rates observed at 25-26 weeks of gestation. RESULTS:Discordant antenatal corticosteroid use and resuscitation, where one and not the other occurred, were more frequent for births at 22 and 23 but not 24 weeks (rate ratio [95% CI] at 22 weeks: 1.7 [1.3-2.2]; 23 weeks: 2.6 [2.2-3.2]; 24 weeks: 1.0 [0.8-1.2]) when compared with 25-26 weeks. Among infants resuscitated at 23 weeks, adjusting each hospital's rate of antenatal corticosteroid use to the average at 25-26 weeks (89.2%) was projected to increase infant survival by 7.1% (95% CI 5.4-8.8%) and survival without severe impairment by 6.4% (95% CI 4.7-8.1%). No significant change in outcomes was projected for infants resuscitated at 22 weeks, where few (n = 22) resuscitated infants received antenatal corticosteroids. CONCLUSIONS:Infants born at 23 weeks were more frequently resuscitated without antenatal corticosteroids than other extremely preterm infants. When resuscitation is intended, consistent provision of antenatal corticosteroids may increase infant survival and survival without impairment. TRIAL REGISTRATION:ClinicalTrials.govNCT00063063 (Generic Database) and NCT00009633 (Follow-Up Study).

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Repeated antenatal corticosteroid treatments adversely affect neural transmission time and auditory thresholds in laboratory rats.

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Repeated antenatal corticosteroid treatments adversely affect neural transmission time and auditory thresholds in laboratory rats.

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