| Developmental Lead Exposure Induces Tactile Defensiveness in Rhesus Monkeys (Macaca Mulatta) Colleen F. Moore,1 Lisa L. Gajewski,2,3 Nellie K. Laughlin,2,4 Melissa L. Luck,2 Julie A. Larson,2,3 and Mary L. Schneider1,2,3 1Department of Psychology, 2Harlow Center for Biological Psychology, and 3Department of Kinesiology, University of Wisconsin-Madison, Madison, Wisconsin, USA; 4Psychology Department, Marquette University, Milwaukee, Wisconsin, USA Abstract
Background: Tactile defensiveness in children is associated with difficult social relations, emotional dysregulation, and inattention. However, there are no studies of lead exposure and tactile defensiveness in children or animals in spite of the fact that lead exposure is also associated with inattention and emotional dysregulation. Objectives: In this study we tested whether lead exposure induces tactile defensiveness in rhesus monkeys. Methods: We tested 61 monkeys from a 3 (no lead, 1-year lead, 2-year lead)  2 (succimer chelation or not) factorial experiment for tactile defensiveness at 4 years of age. Lead-treated monkeys had been orally administered lead in a daily milk solution from 8 days of life to either 1 or 2 years of age to produce blood lead levels of 35–40 mg/dL. Succimer chelation therapy or placebo was administered at 1 year of age. We measured tactile defensiveness using six repeated trials of each of three textures as a swipe to the cheek and neck. Results: Lead-exposed monkeys showed higher negative responses to repeated tactile stimulation compared with controls. Blood lead during the first 3 months of life was positively correlated with the negative response on the tactile defensiveness test. There was an interaction of lead exposure succimer chelation trials, but it is not clear that succimer chelation was beneficial with respect to tactile defensiveness. Conclusions: This is the first report to implicate lead as a potential cause of tactile defensiveness. Research should examine whether lead exposure is associated with tactile defensiveness in children. Key words: lead exposure, sensory processing disorder, succimer chelation, tactile defensiveness, withdrawal response. Environ Health Perspect 116: 1322–1326 (2008) . doi:10.1289/ehp.11203 available via http://dx.doi.org/ [Online 30 May 2008]
Address correspondence to M.L. Schneider, Harlow Center for Biological Psychology, 22 North Charter St., Madison, WI 53715 USA. Telephone: (608) 265-5118. Fax: (608) 262-6020. E-mail: schneider@education.wisc.edu This study was partially supported by National Institute of Environmental Health Sciences grant ES06918 to N.K.L. ; a Wallace Research Foundation grant to M.L.S., and a Vilas Associate Award to C.F.M. A preliminary version of this project was presented in partial fulfillment of the requirements of the Master of Science at the University of Wisconsin-Madison by L.L.G. The authors declare they have no competing financial interests. Received 21 December 2007 ; accepted 30 May 2008.
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