PMID- 10966516
OWN - NLM
STAT- MEDLINE
DCOM- 20001013
LR  - 20190513
IS  - 1096-6080 (Print)
IS  - 1096-0929 (Linking)
VI  - 57
IP  - 1
DP  - 2000 Sep
TI  - Spatial learning and long-term potentiation in the dentate gyrus of the 
      hippocampus in animals developmentally exposed to Aroclor 1254.
PG  - 102-11
AB  - Developmental exposure to polychlorinated biphenyls (PCBs) has been associated 
      with cognitive deficits in children. Rodent studies have revealed impairments in 
      learning tasks involving the hippocampus. The present study sought to examine 
      hippocampal synaptic plasticity in the dentate gyrus and spatial learning in 
      animals exposed to PCBs early in development. Pregnant Long-Evans rats were 
      administered either corn oil (control) or 6 mg/kg/day of a commercial PCB 
      mixture, Aroclor 1254 (A1254) by gavage from gestational day (GD) 6 until pups 
      were weaned on postnatal day (PND) 21. Spatial learning was assessed at 3 months 
      of age in male and female offspring using the Morris water maze. Latency to find 
      a hidden platform that remained in the same position over 20 days of testing did 
      not differ between control and PCB-exposed groups. Neither were group differences 
      evident in a repeated acquisition version of the task in which the platform 
      remained in the same position over the 2 daily trials but was moved to a new 
      spatial location each day. Male littermates of animals in the behavioral study 
      were tested electrophysiologically at 5-7 months of age. Field potentials evoked 
      by perforant path stimulation were recorded in the dentate gyrus under urethane 
      anesthesia. Input/output (I/O) functions were assessed by averaging the response 
      evoked in the dentate gyrus to stimulus pulses delivered to the perforant path in 
      an ascending intensity series. Long-term potentiation (LTP) was induced by 
      delivering a series of brief, high-frequency train bursts to the perforant path 
      at increasing stimulus intensities, and I/O functions were reassessed 1 h later. 
      No differences in baseline synaptic population spike (PS) and excitatory 
      postsynaptic potential (EPSP) slope amplitudes were discerned between the groups 
      prior to train delivery. Post-train I/O functions, however, revealed a decrement 
      in the magnitude of evoked LTP in PCB-exposed animals, and an increase in the 
      train intensity required to induce LTP. The observed dissociation between 
      impaired hippocampal plasticity, in the absence of a detectable deficit in 
      performance of a hippocampal-dependent task, may be due to task complexity, the 
      maintenance of some degree of plasticity in the PCB-exposed animals, or the 
      possibility that intact dentate gyrus LTP may not be requisite for water-maze 
      learning.
FAU - Gilbert, M E
AU  - Gilbert ME
AD  - Neurotoxicology Division, National Health and Environmental Effects Research 
      Laboratory, US Environmental Protection Agency, Research Triangle Park, North 
      Carolina 27711, USA. gilbert.mary@epa.gov
FAU - Mundy, W R
AU  - Mundy WR
FAU - Crofton, K M
AU  - Crofton KM
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - United States
TA  - Toxicol Sci
JT  - Toxicological sciences : an official journal of the Society of Toxicology
JID - 9805461
RN  - 11097-69-1 (Chlorodiphenyl (54% Chlorine))
SB  - IM
MH  - Animals
MH  - Behavior, Animal/drug effects
MH  - Chlorodiphenyl (54% Chlorine)/*toxicity
MH  - Cues
MH  - Dentate Gyrus/*drug effects
MH  - Electrophysiology
MH  - Excitatory Postsynaptic Potentials/drug effects
MH  - Female
MH  - Hippocampus/*drug effects
MH  - Long-Term Potentiation/*drug effects
MH  - Maze Learning/*drug effects
MH  - Pregnancy
MH  - Rats
MH  - Rats, Long-Evans
MH  - Swimming/physiology
EDAT- 2000/08/31 11:00
MHDA- 2000/10/21 11:01
CRDT- 2000/08/31 11:00
PHST- 2000/08/31 11:00 [pubmed]
PHST- 2000/10/21 11:01 [medline]
PHST- 2000/08/31 11:00 [entrez]
AID - 10.1093/toxsci/57.1.102 [doi]
PST - ppublish
SO  - Toxicol Sci. 2000 Sep;57(1):102-11. doi: 10.1093/toxsci/57.1.102.