The effect of postnatal protein malnutrition on spatial learning and memory behavior in rats

Abstract

In most mammalian species, the perinatal period is a critical stage for brain development. Malnutrition during this period may cause impairment in brain function. It is also known that brain derived neurotrophic factor (BDNF) plays an important role in brain development and it is involved in neuron proliferation, growth, and synapse formation. To examine the effect of postnatal protein malnutrition on spatial learning behavior and BDNF level in the brain, six normal pregnant Sprague Dawley rats were divided into two groups, control (CTR) and postnatal protein malnutrition (PM). From the third day after giving birth, the rats were switched to semi-purified diets containing 8% protein for PM group and 20% protein for CTR group. The pups were weaned at four weeks of age and maintained on lab chow afterwards. The spatial learning ability of the pups from both CTR and PM groups were evaluated at four and ten weeks of age by a Morris water maze test. At the end of the behavior test, the pups were sacrificed and brain tissues were dissected and assayed for BDNF levels using an ELISA kit. It was found that the spatial learning ability was significantly impaired in protein malnourished pups at ten weeks of age. The BDNF level in the hippocampus was significantly lower (p<0.05) in protein malnourished pups at both four and ten weeks of age when compared with the control animals. It is speculated that the detrimental effect of postnatal protein malnutrition on the brain functional development may partially be attributed to a reduced BDNF production.

The study was partially supported by Hong Kong Research Grants Council.