Gene-pesticide interactions and ADHD

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Attention Deficit Hyperactivity Disorder (ADHD) is the most prevalent neurodevelopmental psychiatric disorder (9.4% prevalence in children; 4.4% in adults) and is polygenic. A novel gene associated with ADHD is Latrophilin-3 found in striatum, hippocampus, cerebellum, prefrontal cortex (PFC), and amygdala. In humans, there are 21 variants of LPHN3 associated with ADHD. Some pesticides may interact with ADHD genetic risk factors to trigger or exacerbate the symptoms. We found that the common pyrethroid, deltamethrin (DLM), administered prior to weaning in rats causes long-term behavioral, neurochemical, and electrophysiological effects. We developed the first KO rats of Lphn3. Lphn3 KO rats are hyperactive, hyper-reactive to startle stimuli, and cognitively impaired. This PAR-19-386 “Environmental Risks for Psychiatric Disorders: Biological Basis of Pathophysiology” seeks models that will elucidate Gene x Environment interactions related to neuropsychiatric disorders, such as ADHD. We hypothesize that Lphn3-/- and Lphn3+/- rats will interact with DLM (Type II pyrethroid) or permethrin (PRM, Type I pyrethroid) to exacerbate an ADHD-like phenotype. Specific Aim 1: Determine the effects of DLM in Lphn3-/-, Lphn3+/-, and wildtype (WT) rats on activity, reactivity, learning and memory (L&M), dopamine (DA) and NMDA markers, and apoptosis. Aim-1a: Compare WT rats with Lphn3-/- and Lphn3+/- rats administered 0, 0.5, or 2.0 mg/kg DLM from P3-20 for changes in activity, acoustic and tactile startle (including prepulse inhibition (PPI)) egocentric, allocentric, and working L&M, and for changes in DA and NMDA-R markers in various brain regions, including markers for programmed cell death. Aim-1b, neurochemical outcomes in rats not behaviorally tested. Specific Aim 2: Determine the effects of PRM in Lphn3-/-, Lphn3+/- rats vs. WT rats on the outcomes used in Aim-1. Aim-2a: Same as Aim-1a with PRM. Aim-2b: Same as Aim-1b with PRM. Specific Aim 3: Determine the effects of DLM in adult Lphn3- /-, Lphn3+/- rats vs. WT rats. Aim-3a: same outcomes as in Aim-1a. Adults with ADHD are an understudied and a population susceptible for higher exposure to pyrethroids from occupational exposure, making Aims 3 and 4 important. Aim-3b: Same as Aim-1b in adult rats. Specific Aim 4: Determine the effects of PRM in adult Lphn3-/-, Lphn3+/- rats vs. WT rats. Aim-4a: Same outcomes used in Aim-1a. Aim-4b: Same as Aim-1b in adult rats not behaviorally tested. Impact: ADHD interferes with normal development, costs billions to treat and manage, yet we know little about environmental contributions to those with ADHD. Insecticides are suspected in ADHD but such interactions between gene and environment are not established. Lphn3-/- and Lphn3+/- rats represent a novel approach to probing the effects of exposure to pyrethroids using a known ADHD genetic susceptibility. The model will shed new light on how a gene known to be associated with ADHD affects the behavioral and biochemical effects of prototypical pyrethroids. Interaction data can be used for risk assessment and help provide safeguards against pyrethroid exposure for those with ADHD.