Perinatal nutritional iron deficiency reduces hippocampal synaptic transmission but does not impair short- or long-term synaptic plasticity

Studies show that perinatal nutritional iron deficiency (ID) produces learning and memory impairments in humans and animals. This suggests that the functional physiology of learning and cognitive centers in the brain, such as the hippocampus, may be compromised by developmental ID. The present study used electrophysiological brain slice methods to examine multiple measures of hippocampal synaptic efficacy from rats that were subjected to perinatal ID diets or control (CN) diets. Measures of synaptic efficacy were obtained from the first and last synaptic regions of the hippocampal tri-synaptic loop (i.e. the dentate gyrus (DG) and CA1). Rats were placed on ID or CN diets on gestational day 11, and hippocampal brain slices were prepared between postnatal day 25 and 37. Results show that ID slices were not impaired in short-term (i.e. paired-pulse facilitation (PPF)) or long-term measures (i.e. long-term potentiation (LTP)) of synaptic plasticity in either the DG or CA1 areas. Input-output (IO) measures showed that synaptic transmission was reduced in both of these areas in the ID slices when compared with the CN slices. This suggests that ID-induced learning deficits may be the result of reductions in synaptic transmission throughout the hippocampus, and possibly in other learning and memory centers.