Neonatal isolation enhances hippocampal dentate response to tetanization in freely moving juvenile male rats.
The impact of early neonatal isolation on measures of hippocampal neuronal plasticity was examined in freely moving male rats at 30 days of age. Beginning on Postnatal (PN) Day 2, one-half of pups from each experimental litter were individually isolated from the nest, dam, and siblings for a period of 1 h per day over PN Days 2-9, while their siblings remained in the nest. In addition, randomly selected litters served as unhandled controls. On PN Day 26 all pups were weaned and chronically implanted for recording of evoked field potentials and induction of hippocampal longterm potentiation. At 30 days of age, pups from the three treatment groups (isolated, nonisolated siblings, and unhandled controls) were tested for their ability to establish and maintain long-term potentiation across the perforant path/hippocampal dentate granule cell synapse. Changes in population EPSP slope and population spike amplitude (PSA) recorded following tetanization were used to assess the effects of neonatal isolation of hippocampal response measures. No significant between-group differences were obtained for input/output response curves constructed prior to tetanization. All three groups showed immediate and significant enhancement of the PSA measure at 15 min posttetanization. The level of PSA enhancement obtained from previously isolated pups was significantly greater than that obtained from both the nonisolated sibling and unhandled control groups.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D017774:Long-Term Potentiation / Q000502:physiology; D008297:Male; D008426:Maternal Deprivation; D009473:Neuronal Plasticity / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012934:Social Isolation; D013315:Stress, Psychological / Q000503:physiopathology