AUTHOR BLOCK:
*N. JIMENEZ-RIVERA¹, L. MÉNDEZ-SANTACRUZ^1,2, T. JIMÉNEZ-RIVERA¹, L. VICENTE-RODRÍGUEZ³, P. VÁZQUEZ-MARTÍNEZ³, D. NAZARIO-MARTÍNEZ³, M. CÁCERES-CHACÓN¹, O. MARTÍNEZ-GUZMÁN¹, D. SIERRA-MERCADO¹;
¹Anat. & Neurobio., Univ. Puerto Rico Sch. of Med., San Juan, PR; ²Biol., Univ. of Puerto Rico Río Piedras Campus, San Juan, PR; ³Biol., Univ. of Puerto Rico Cayey Campus, Cayey, PR

Abstract:
INTRODUCTION: Glyphosate, the active ingredient in glyphosate-based herbicides, was initially considered safe for mammals since it exerts its effect by inhibiting a metabolic route that is not present in mammals. However, glyphosate has become a significant environmental threat due to excessive use. The increased risk of human exposure to glyphosate through contaminated water sources and food products suggests a link between exposure to glyphosate and the development of emotional disorders such as anxiety and pain. The Environmental Protection Agency regulates glyphosate, and it is unlikely that humans are exposed to levels above those permitted. However, the effect of prolonged exposure to low doses of glyphosate on anxiety and pain remains poorly studied. Inappropriate interpretation of threat and excess avoidance are hallmarks of anxiety disorders and are often the most debilitating and life altering symptoms of these disorders. This makes studying the effect of glyphosate on avoidance and pain-related behaviors extremely necessary.

METHODS: We administered either glyphosate-contaminated drinking water (n=16) or filtered water (n=16) for controls to female rats and performed behavioral studies for avoidance and pain-related behaviors. We hypothesized that glyphosate alters neuronal activity in brain regions important for the regulation of these behaviors. For avoidance, rats were conditioned in an operant chamber to auditory tones co-terminating with a mild footshock. An acrylic platform in the opposite corner of the sucrose-delivering bar allowed rats to avoid the shocks. We are evaluating behavioral changes and neuronal activity in brain regions implicated in avoidance and pain-related behaviors.

RESULTS: Our baseline results of the Vonfrey test indicate comparable levels of pain tolerance on the left paw (Control: 14.0 g + 1.37 ; Gly: 13.79 g + 1.47) and right paw (Control: 9.0 g + 0.99 ; Gly: 11.21 g + 1.40).

CONCLUSION: Understanding the fundamental mechanism of how herbicide consumption impacts will help in the understanding of the biological basis for how environmental exposures impact the risk for psychiatric disorders.

IACUC APPROVAL NUMBER: A120418

ACKNOWLEDGMENTS: NIEHS R21ES034191 to DS-M and FG-V; NINDS R21NS119991, Brain & Behavior Research Foundation, PRCTRC Pilot, NIGMS COBRE II, RCMI8G12MD00760, Hispanics in Research Capability (HiREC), and Title V Pilot Project (PiP) to DS-M, NSF PRCEN graduate fellowship to MCC, NSF PRCEN undergraduate fellowship and Supplement on R21 ES034191 to NJ-R, and UPR Med Sci Campus Chancellor’s Office and School of Medicine Deanship.