preparation-rhythmically-active-vitro-neonatal-rodent-brainstem

Preparation of Rhythmically-active In Vitro Neonatal Rodent Brainstem-spinal Cord and Thin Slice

Mammalian inspiratory rhythm is generated from a neuronal network in a region of the medulla called the preB&#246;tzinger complex (pBC), which produces a ...

Loma Linda University

Pre-term infants are at greater risk for systemic infection due to an underdeveloped immune system. Airway infection results in immune up-regulation of early pro-inflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNFα) in the brainstem. Current treatment for neonatal infection involves antibiotic administration. We previously showed that LPS injected into the trachea of neonatal rats causes changes in breathing and in IL-1β expression in the nucleus tractus solitarii (NTS) and hypoglossal motor nucleus (XII). We hypothesize that lipopolysaccharide (LPS) instilled in the trachea also causes the up-regulation of IL-6 and TNFα in the brainstem autonomic control regions. To test this hypothesis we injected LPS into the trachea of rat pups (postnatal ages 10-12days) and then assessed changes in IL-6 and TNFα. Vagal nerve stimulation has been used in the treatment of many inflammatory disorders, including sepsis. Our experiments show that VNS attenuates the upregulation of IL-6 and TNFα caused by LPS and may be a viable alternative to antibiotics.

Vagal nerve stimulation attenuates IL-6 and TNFα expression in respiratory regions of the developing rat brainstem.

We hypothesize that developmental changes in motoneuron volume or surface area in the hypoglossal motor nucleus (XII) can alter the biophysical properties that contribute to motor output. We used the Golgi-Cox technique to stain developing hypoglossal motoneurons (XII MNs) at three postnatal ages (P3, 10, & 17). We removed Sprague-Dawley rat pup brains, processed, sectioned, stained, imaged, and performed 3D reconstructions to quantify the morphometrics of XII MNs. We then used the simulation environment, NEURON, to model the biophysical properties from digitally reconstructed neurons and compared our results to previously published experiments. The total volume of neurons increased from 4766 μ m for P3 to 16,904 μ m for P17 while the total surface area increased from 4258 μ m to 13,510 μ m respectively. The P3 simulations required a 10-fold reduction in the hyperpolarization-activated current and doubling of the membrane capacitance to match experimental results. XII MN morphology showed a direct relationship with passive electrophysiological properties and recapitulates the changes seen experimentally.

Modeling hypoglossal motoneurons in the developing rat.

 Anterior lens capsule vascularity (ALCV) is resorbed in the developing fetus from 27 to 35 weeks gestation. In this pilot study, we evaluated the feasibility and validity of combining smartphone ophthalmoscope videos of ALCV and image analysis for gestational age estimation.  ALCV videos were captured longitudinally in preterm neonates from delivery using a PanOptic® Ophthalmoscope with an ® adapter (Welch-Allyn). ALCV video frames were manually selected and quantified using semi-automatic image analysis. A predictive model based on ALCV features was compared to gold-standard ultrasound gestational age estimates.  A total of 64 image-capture sessions were carried out in 24 neonates. Ultrasound-estimated gestational age and ALCV-predicted gestational age estimates indicate that the two methods are similar ( = 0.78,  < 0.0001). ALCV estimates of gestational age were within 0.11 ± 1.3 weeks of ultrasound estimates. In the final model, gestational age was predicted within ± 1 week for 54% and within ± 2 weeks for 86% of the measures.  This novel application of smartphone ophthalmoscopy and ALCV image analysis may provide a safe, accurate and non-invasive technology to estimate postnatal gestational age, especially in low income countries where gestational age may not be known at birth.

Article	Year
Vagal nerve stimulation attenuates IL-6 and TNFα expression in respiratory regions of the developing rat brainstem. Respiratory physiology & neurobiology\| PubMed ID: 27049312	2016
Modeling hypoglossal motoneurons in the developing rat. Respiratory physiology & neurobiology\| PubMed ID: 30056243	2018
Estimation of Gestational Age via Image Analysis of Anterior Lens Capsule Vascularity in Preterm Infants: A Pilot Study. Frontiers in pediatrics\| PubMed ID: 30842940	2019

Christopher G. Wilson

Biography

JoVE Journal Publications

Other Publications