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Long-term effects of early undernutrition and environmental stimulation on learning performance of adult rats
Insights
Early undernutrition in rats did not affect maze learning, but environmental stimulation improved performance in both control and undernourished groups. Neurochemical changes were observed in undernourished brains, but not altered by stimulation.
Area of Science:
- Neuroscience
- Developmental Biology
- Animal Behavior
Background:
- Early life undernutrition can impact brain development and cognitive function.
- Environmental enrichment is known to promote neural plasticity and enhance learning.
Purpose of the Study:
- To investigate the long-term effects of early undernutrition and subsequent environmental stimulation on learning and neurochemistry in rats.
- To determine if environmental stimulation can ameliorate deficits caused by early nutritional challenges.
Main Methods:
- Rats were subjected to early undernutrition (large litters) or control conditions (small litters).
- Post-weaning, animals received either environmental stimulation (group housing, handling, exploration) or no stimulation for 11 weeks.
- Cognitive performance was assessed using the Hebb-Williams maze, and brain neurochemistry (DNA, cholesterol) was analyzed.
Main Results:
- Early undernutrition did not impair Hebb-Williams maze performance.
- Environmental stimulation significantly improved learning performance in both control and previously undernourished rats.
- Undernutrition reduced forebrain and cerebellum DNA and cholesterol; brainstem was least affected.
- Environmental stimulation did not alter neurochemical parameters.
Conclusions:
- Early undernutrition alone did not cause lasting cognitive deficits in this rat model.
- Environmental stimulation can enhance learning and cognitive flexibility, even in previously undernourished individuals.
- While undernutrition affects brain composition, environmental enrichment's cognitive benefits may operate independently of these specific neurochemical changes.
Abstract:
Early undernutrition was achieved in rats by increasing litter size; the undernourished groups were reared from birth to 21 days in litters of 18 pups per dam and the control groups in litters of six pups per dam. Each of these groups was divided at weaning into two sub-groups: previously undernourished, stimulated (PUS+) and non-stimulated (PUS-); and control, stimulated (CS+) and non-stimulated (CS-). From weaning, all animals were fed ad libitum. Environmental manipulation began at weaning and lasted 11 weeks. "Stimulated" rats were maintained in colonies of three per cage, were handled for 5 minutes each day and allowed to explore a "stimulation chamber" for 30 minutes. All groups were tested in a Hebb-Williams maze at 100 approximately 10 days of age. The nutritional treatment did not impair Hebb-Williams performance, and environmental stimulation improved the learning performance both in control and previously undernourished groups. Neither nutritional nor stimulation treatment affected intraproblem learning. Total DNA and cholesterol were reduced in forebrain and cerebellum in undernourished rats. Brain stem was the region of the CNS least affected by early undernutrition. Environmental manipulation did not modify neurochemical parameters.