Postnatal Bacterial Infection Model
Objective: To explore long-term effects of early-life bacterial infection on physiology and behavior by examining whether neonatal E. coli infection affects memory formation and adult immune responses
This is a Postnatal Bacterial Infection Model protocol using rat as the model organism. The procedure involves 6 procedural steps, 2 materials. Extracted from a 2009 paper published in Frontiers in Behavioral Neuroscience.
Model and subjects
rat • Not specified • unknown • Postnatal day 4 (P4) at injection; tested in adulthood • Not specified
Study window
~2 day study window
Core workflow
Postnatal Day 4 Injection • Acute Response Monitoring • Brain Cytokine Analysis
Primary readouts
- Circulating cytokine levels (IL-1β, IL-6, TNF)
- Corticosterone levels
- Brain IL-1β mRNA and protein levels
- Hippocampal-dependent memory formation (context pre-exposure task freezing behavior)
Key equipment and reagents
Use this page as an execution guide, then fall back to the source paper whenever you need exact exclusions, dosing details, or assay-specific caveats.
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Protocol Steps
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Postnatal Day 4 Injection
Rats receive subcutaneous injection of either PBS (control) or live E. coli (non-lethal dose)
Note: P4 was selected based on models of neonatal LPS challenge in rats and represents a time relatively comparable to the third trimester in humans
View evidence from paper
“Rats are injected subcutaneously on postnatal day (P) 4 with phosphate-buffered-saline (PBS) or a non-lethal dose of live Escherichia coli”
Acute Response Monitoring
Monitor circulating cytokines (IL-1β, IL-6, TNF) and corticosterone levels following infection
Note: Neonatal E. coli infection markedly increases circulating cytokines and corticosterone for at least 48 hours after infection
View evidence from paper
“Our data have demonstrated that neonatal E. coli infection in pups markedly increases circulating cytokines (IL-1β, IL-6, TNF) and the primary stress hormone, corticosterone, for at least 48 h after infection”
Brain Cytokine Analysis
Measure IL-1β mRNA and protein levels within the brain; analyze other cytokines (IL-6, TNF) for comparison
Note: Significant and specific increase in IL-1β mRNA and protein occurs in brain, but not in other analyzed cytokines
View evidence from paper
“Within the brain, there is a significant and specific increase in IL-1β mRNA and protein (Bilbo et al., 2005a), but not in other analyzed cytokines (IL-6, TNF), compared to PBS injection”
Context Pre-exposure Task - Day 1
Pre-expose rat to conditioning context for several minutes to allow sampling of environment and storage of context features
Note: This stage is critically dependent on the hippocampus. Performed the day before shock conditioning
View evidence from paper
“if a rat is pre-exposed to the context for several minutes the day before, immediate shock conditioning will then produce substantial freezing on a subsequent test day”
Context Pre-exposure Task - Day 2
Place rat into conditioning context and immediately deliver shock
Note: Immediate shock prevents context sampling. This stage is critically dependent on the hippocampus
View evidence from paper
“when a rat is placed into a conditioning context and immediately shocked, he later displays little or no conditioned fear (freezing) to the context”
Context Pre-exposure Task - Test Day
Test rat for conditioned fear response (freezing) to the context
Note: Freezing behavior indicates successful memory formation of context. This stage is critically dependent on the hippocampus
View evidence from paper
“immediate shock conditioning will then produce substantial freezing on a subsequent test day”