title: Developmental lead exposure causes startle response deficits in zebrafish.
abstract: Lead (Pb(2+)) exposure continues to be an important concern for fish populations. Research is required to assess the long-term behavioral effects of low-level concentrations of Pb(2+) and the physiological mechanisms that control those behaviors. Newly fertilized zebrafish embryos (<2h post fertilization; hpf) were exposed to one of three concentrations of lead (as PbCl(2)): 0, 10, or 30 nM until 24 hpf. (1) Response to a mechanosensory stimulus: Individual larvae (168 hpf) were tested for response to a directional, mechanical stimulus. The tap frequency was adjusted to either 1 or 4 taps/s. Startle response was recorded at 1000 fps. Larvae responded in a concentration-dependent pattern for latency to reaction, maximum turn velocity, time to reach V(max) and escape time. With increasing exposure concentrations, a larger number of larvae failed to respond to even the initial tap and, for those that did respond, ceased responding earlier than control larvae. These differences were more pronounced at a frequency of 4 taps/s. (2) Response to a visual stimulus: Fish, exposed as embryos (2-24 hpf) to Pb(2+) (0-10 μM) were tested as adults under low light conditions (≈ 60 μW/m(2)) for visual responses to a rotating black bar. Visual responses were significantly degraded at Pb(2+) concentrations of 30 nM. These data suggest that zebrafish are viable models for short- and long-term sensorimotor deficits induced by acute, low-level developmental Pb(2+) exposures.
authors.affiliation: Department of Biology, American University, Washington, DC 20016, USA.
authors.forename: Clinton
authors.initials: C
authors.lastname: Rice
authors.forename: Jugal K
authors.initials: JK
authors.lastname: Ghorai
authors.forename: Kathryn
authors.initials: K
authors.lastname: Zalewski
authors.forename: Daniel N
authors.initials: DN
authors.lastname: Weber
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004625:Embryo, Nonmammalian; D004924:Escape Reaction / Q000187:drug effects*; D007814:Larva / Q000187:drug effects / Q000502:physiology; D007854:Lead / Q000493:pharmacokinetics / Q000633:toxicity*; D013216:Reflex, Startle / Q000187:drug effects*; D013997:Time Factors; D023382:Toxicity Tests, Acute; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics / Q000633:toxicity*; D015027:Zebrafish / Q000196:embryology / Q000502:physiology*
chemical_list: D014874:Water Pollutants, Chemical; D007854:Lead