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Acoustic startle responses of protein malnourished rats
Insights
Early protein malnutrition did not cause general hyperreactivity to aversive stimuli. Postweaning low protein diets, however, increased acoustic startle responses in rats, suggesting a specific impact on this response.
Area of Science:
- Neuroscience
- Nutritional Science
- Animal Behavior
Background:
- Early life nutrition significantly impacts neurodevelopment and behavior.
- Protein malnutrition is a potential stressor that may alter responses to stimuli.
Purpose of the Study:
- To investigate if early protein malnutrition leads to general hyperreactivity to aversive stimuli.
- To examine the effects of preweaning and postweaning protein restriction on acoustic startle responses.
Main Methods:
- Acoustic startle responses were measured in rats using floor movements and electromyography (EMG).
- Rats were subjected to different protein diets during preweaning and postweaning periods.
- Body weight and habituation rates were also assessed.
Main Results:
- Preweaning protein restriction did not affect acoustic startle responses.
- Postweaning protein restriction, particularly switching from high to low protein diets, increased EMG-measured startle responses.
- Floor movement-based startle measures were confounded by body weight, while EMG measures showed diet-related differences.
Conclusions:
- Early protein malnutrition does not induce general hyperreactivity to aversive stimuli.
- Postweaning protein restriction can specifically enhance acoustic startle responses.
- Dietary interventions during development have distinct effects on neurobehavioral outcomes.
Abstract:
Acoustic startle responses were measured as part of a systematic attempt to determine if early protein malnutrition leads to a general hyperreactivity to aversive stimulation. In Experiment 1 startle responses transduced by floor movements were not reliably influenced by protein restriction in the preweaning or postweaning periods. The magnitude of the startle response, however, was positively correlated with body weight, partly as a consequence of the transduction method. Thus, differences in body weight might have obscured diet-related differences in startle amplitude. In Experiment 2 startles were recorded as electromyographic responses of the neck muscles and were larger in rats fed the low protein diet postweaning, especially in rats switched from high to low protein conditions at weaning. There was no indication that rats subjected to preweaning protein malnutrition were hyperreactive to aversive stimulation. In Experiment 1 it was also found that mean startle amplitudes were larger in young adults, 60 or 90 days old, than in 35-day-old rats, partly because there was less habituation in the adults.