Effect of Environmental Enrichment during Nutritional Rehabilitation on Body Growth, Blood Parameters and Cerebral Cortical Development of Rats

Environmental enrichment has been reported to aid recovery from behavioral deficits associated with malnutrition in infants and young rats. This study investigated whether corresponding neuroanatomical changes could be detected. Rats were suckled either by well-fed dams or dams malnourished during lactation. At weaning, well-fed males were either housed in pairs (standard condition, SC) or 12 per large cage with toys (enriched condition, EC) and fed a 17% protein diet (SC control and EC control, respectively). Malnourished pups were fed either a 17% (rehabilitation; “rehab”) or a 6% (low protein) protein diet and housed in the SC or EC environment (SC rehab, EC rehab, SC low protein, and EC low protein). After 30 d there were no differences in hematocrit, serum total protein and albumin levels between SC and EC animals. Rehab rats had significantly lower serum total protein and albumin levels than did controls. Cortical thickness and dendritic branching of occipital cortex pyramidal cells were evaluated. Early malnutrition did not permanently affect cortical thickness. EC rehab rats had thicker cortices than did SC rehab rats at almost all locations measured. SC rehab rats had fewer high order dendrites than did SC controls. The difference in dendritic branching between EC and SC rats was 44% among rehab rats, 21% among controls and 11% (not significant) among low protein—fed rats. Environmental enrichment during nutritional rehabilitation enhances dendritic branching and thickness of the occipital cortex.