Gestational and perinatal exposure to diazinon causes long-lasting neurobehavioral consequences in the rat.
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Diazinon is a widely-used organophosphate pesticide. Pulsatile exposure to diazinon during neonatal development has previously been shown cause long-term neurobehavioral impairments in rats. However, the effects of chronic low concentration exposures during perinatal development remain unclear. This experiment evaluated such effects in Sprague-Dawley rats by implanting osmotic pumps in breeder females prior to conception (N = 13-15 litters per condition) which then delivered chronic, zero order kinetic low-level infusions of 0, 114 or 228 ug/day of diazinon throughout pregnancy. One male and one female from each litter was assessed with a battery of behavioral tests that continued from four weeks of age into adulthood. Litter was used as the unit of variance for the analysis of variance test of significance, with sex as a within litter factor. Diazinon treatment condition was the between subjects factor and time or sessions were repeated measures. Chronic diazinon exposure from pre-mating until the neonatal period caused a significant (p < 0.05) increase in percent of time spent on the open arms of the elevated plus maze, an index of risk-taking behavior. Gestational and lactational diazinon exposure also caused a significant (p < 0.05) degree of hyperactivity in the Figure-8 apparatus during adolescence, specifically affecting the early part of the hour-long test session. This effect had dissipated by the time the rats reached adulthood. Diazinon exposure also caused a significant impairment in novel object recognition, a test of cognitive function. Offspring exposed to 228 ug/day diazinon (p < 0.05) showed significantly less preference for the novel vs. familiar object than controls during the first five minutes of the novel object recognition test.
Published Version (Please cite this version)
Hawkey, Andrew, Erica Pippen, Hannah White, Joseph Kim, Eva Greengrove, Bruny Kenou, Zade Holloway, Edward D Levin, et al. (2020). Gestational and perinatal exposure to diazinon causes long-lasting neurobehavioral consequences in the rat. Toxicology, 429. p. 152327. 10.1016/j.tox.2019.152327 Retrieved from https://hdl.handle.net/10161/29506.
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Dr. Levin is Chief of the Neurobehavioral Research Lab in the Psychiatry Department of Duke University Medical Center. His primary academic appointment is as Professor in the Department of Psychiatry and Behavioral Sciences. He also has secondary appointments in the Department Pharmacology and Cancer Biology, the Department of Psychological and Brain Sciences and the Nicholas School of the Environment at Duke. His primary research effort is to understand basic neural interactions underlying cognitive function and addiction and to apply this knowledge to better understand cognitive dysfunction and addiction disorders and to develop novel therapeutic treatments.
The three main research components of his laboratory are focused on the themes of the basic neurobiology of cognition and addiction, neurobehavioral toxicology and the development of novel therapeutic treatments for cognitive dysfunction and substance abuse. Currently, our principal research focus concerns nicotine. We have documented the basic effects of nicotine on learning memory and attention as well as nicotine self-administration. We are continuing with more mechanistic studies in rat models using selective lesions, local infusions and neurotransmitter interaction studies. We have found that nicotine improves memory performance not only in normal rats, but also in rats with lesions of hippocampal and basal forebrain connections. We are concentrating on alpha7 and alpha4beta2 nicotinic receptor subtypes in the hippocampus, amygdala , thalamus and frontal cortex and how they interact with dopamine D1 and D2 and glutamate NMDA systems with regard to memory and addiction. I am also conducting studies on human cognitive behavior. We have current studies to assess nicotine effects on attention, memory and mental processing speed in schizophrenia, Alzheimer's Disease and Attention Deficit Hyperactivity Disorder. In the area of neurobehavioral toxicology, I have continuing projects to characterize the adverse effects of prenatal and adolescent nicotine exposure. Our primary project in neurobehavioral toxicology focuses on the cognitive deficits caused by the marine toxins. The basic and applied aims of our research complement each other nicely. The findings concerning neural mechanisms underlying cognitive function help direct the behavioral toxicology and therapeutic development studies, while the applied studies provide important functional information concerning the importance of the basic mechanisms under investigation.
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