title: Developmental exposure to polychlorinated biphenyls interferes with experience-dependent dendritic plasticity and ryanodine receptor expression in weanling rats.
abstract: BACKGROUND
  Neurodevelopmental disorders are associated with altered patterns of neuronal connectivity. A critical determinant of neuronal connectivity is the dendritic morphology of individual neurons, which is shaped by experience. The identification of environmental exposures that interfere with dendritic growth and plasticity may, therefore, provide insight into environmental risk factors for neurodevelopmental disorders.
  
  
  OBJECTIVE
  We tested the hypothesis that polychlorinated biphenyls (PCBs) alter dendritic growth and/or plasticity by promoting the activity of ryanodine receptors (RyRs).
  
  
  RESULTS
  The Morris water maze was used to induce experience-dependent neural plasticity in weanling rats exposed to either vehicle or Aroclor 1254 (A1254) in the maternal diet throughout gestation and lactation. Developmental A1254 exposure promoted dendritic growth in cerebellar Purkinje cells and neocortical pyramidal neurons among untrained animals but attenuated or reversed experience-dependent dendritic growth among maze-trained littermates. These structural changes coincided with subtle deficits in spatial learning and memory, increased [3H]-ryanodine binding sites and RyR expression in the cerebellum of untrained animals, and inhibition of training-induced RyR upregulation. A congener with potent RyR activity, PCB95, but not a congener with negligible RyR activity, PCB66, promoted dendritic growth in primary cortical neuron cultures and this effect was blocked by pharmacologic antagonism of RyR activity.
  
  
  CONCLUSIONS
  Developmental exposure to PCBs interferes with normal patterns of dendritic growth and plasticity, and these effects may be linked to changes in RyR expression and function. These findings identify PCBs as candidate environmental risk factors for neurodevelopmental disorders, especially in children with heritable deficits in calcium signaling.
authors.affiliation: Center for Research on Occupational and Environmental Toxicology, Oregon Health & Science University, Portland, Oregon, USA.
authors.forename: Dongren
authors.initials: D
authors.lastname: Yang
authors.forename: Kyung Ho
authors.initials: KH
authors.lastname: Kim
authors.forename: Andrew
authors.initials: A
authors.lastname: Phimister
authors.forename: Adam D
authors.initials: AD
authors.lastname: Bachstetter
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Ward
authors.forename: Robert W
authors.initials: RW
authors.lastname: Stackman
authors.forename: Ronald F
authors.initials: RF
authors.lastname: Mervis
authors.forename: Amy B
authors.initials: AB
authors.lastname: Wisniewski
authors.forename: Sabra L
authors.initials: SL
authors.lastname: Klein
authors.forename: Prasada Rao S
authors.initials: PR
authors.lastname: Kodavanti
authors.forename: Kim A
authors.initials: KA
authors.lastname: Anderson
authors.forename: Gary
authors.initials: G
authors.lastname: Wayman
authors.forename: Isaac N
authors.initials: IN
authors.lastname: Pessah
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Lein