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Updated: Aug 16, 2026
Modeling Encephalopathy of Prematurity Using Prenatal Hypoxia-ischemia with Intra-amniotic Lipopolysaccharide in Rats
Published on: November 20, 2015
Minocycline reduces lipopolysaccharide-induced neurological dysfunction and brain injury in the neonatal rat
Lir-Wan Fan1, Yi Pang, Shuying Lin
1Department of Pediatrics, Division of Newborn Medicine, University of Mississippi Medical Center, Jackson, Mississippi 39216-4504, USA.
Abstract:
Preferential brain white matter injury and hypomyelination induced by intracerebral administration of the endotoxin lipopolysaccharide (LPS) in the neonatal rat brain has been characterized as associated with the activation of microglia. To examine whether inhibition of microglial activation might provide protection against LPS-induced brain injury and behavioral deficits, minocycline (45 mg/kg) was administered intraperitoneally 12 hr before and immediately after an LPS (1 mg/kg) intracerebral injection in postnatal day 5 (P5) Sprague-Dawley rats and then every 24 hr for 3 days. Brain injury and myelination were examined on postnatal day 21 and the tests for neurobehavioral toxicity were carried out from P3 to P21. LPS administration resulted in severe white matter injury, enlarged ventricles, deficits in the hippocampus, loss of oligodendrocytes and tyrosine hydroxylase neurons, damage to axons and dendrites, and impaired myelination as indicated by the decrease in myelin basic protein immunostaining in the P21 rat brain. LPS administration also significantly affected physical development (body weight) and neurobehavioral performance, such as righting reflex, wire hanging maneuver, cliff avoidance, locomotor activity, gait analysis, and responses in the elevated plus-maze and passive avoidance task. Treatment with minocycline significantly attenuated the LPS-induced brain injury and improved neurobehavioral performance. The protective effect of minocycline was associated with its ability to attenuate LPS-induced microglial activation. These results suggest that inhibition of microglial activation by minocycline may have long-term protective effects in the neonatal brain on infection-induced brain injury and associated neurologic dysfunction in the rat.
Insights
Minocycline treatment protected neonatal rat brains from lipopolysaccharide (LPS)-induced white matter injury and neurobehavioral deficits by inhibiting microglial activation. This suggests minocycline
Area of Science:
- Neuroscience
- Toxicology
- Developmental Biology
Background:
- Neonatal brain injury, particularly white matter damage and hypomyelination, is often linked to microglial activation.
- Lipopolysaccharide (LPS) administration in neonatal rats causes significant white matter injury and neurobehavioral impairments.
Purpose of the Study:
- To investigate if inhibiting microglial activation with minocycline can protect against LPS-induced neonatal brain injury and associated behavioral deficits.
- To evaluate the long-term effects of minocycline treatment on neurodevelopment and neurological function following LPS exposure.
Main Methods:
- Neonatal Sprague-Dawley rats at postnatal day 5 received intracerebral LPS injection, followed by intraperitoneal minocycline administration before and after LPS exposure, with continued dosing for 3 days.
- Brain injury, myelination status (myelin basic protein immunostaining), and oligodendrocyte/neuronal survival were assessed at postnatal day 21.
- Neurobehavioral toxicity was evaluated from postnatal day 3 to P21, including tests for physical development, reflexes, motor skills, and cognitive functions.
Main Results:
- LPS administration led to severe white matter injury, ventricular enlargement, hippocampal deficits, loss of oligodendrocytes and tyrosine hydroxylase neurons, axonal/dendritic damage, and impaired myelination.
- LPS significantly impacted physical development and neurobehavioral performance across various tests.
- Minocycline treatment significantly reduced LPS-induced brain damage and improved neurobehavioral outcomes, correlating with attenuated microglial activation.
Conclusions:
- Inhibition of microglial activation by minocycline offers significant protection against infection-induced brain injury in the neonatal rat model.
- Minocycline treatment demonstrates potential for mitigating long-term neurological dysfunction following neonatal brain injury caused by endotoxin exposure.
