Discipline: Biological Sciences
Subcategory: Cell and Molecular Biology
Luis Enrique Martinetti - University of Texas at El Paso
Co-Author(s): Anahis Tena, Eduardo Peru, Carla Loyola Baltazar, and Karine Fenelon, University of Texas at El Paso, El Paso, TX
Lead (Pb) is a ubiquitous environmental heavy metal that can cause behavioral and cognitive deficits. Even Low-level Pb induces learning and memory impairments in children from low income neighborhoods found across the United States, including the El Paso-Ciudad Juarez border region. Numerous studies reported that high-levels Pb exposure alters the function of the hippocampus. However, the mechanisms by which lowest-level Pb affects neuronal function are still ill defined, due to the lack of animal models of low Pb exposure. In this study, we compared adult mice that were not exposed to Pb (control) to adult mice exposed from birth to post-natal day 28 to either high Pb levels (330 ppm) or low Pb levels (30 ppm). The 30 ppm exposure was specifically used because it was shown to yield blood Pb levels matching those observed in children of the El Paso region (Sobin et al., 2009 and 2011). Mice exposed to such low-level Pb showed poorer exploratory ambulation (FloresMontoya and Sobin, 2014) and poorer novel odor discrimination (Flores-Montoya et al, in review), behaviors which are hippocampus-dependent. Using both high and low Pb exposed mice, extracellular field electrophysiological recordings were performed in the CA1 region of acute hippocampal slices. Our results revealed synaptic transmission and short-term synaptic depression abnormalities in both low (N = 9) and high (N = 9) Pb levels exposed mice compared to control mice (N = 17). In addition, previous work in children had shown that low-level Pb exposure is associated with deficits in working memory (Sobin et al, unpublished data), which depends on the functional integrity between the hippocampus and the prefrontal cortex (PFC). Therefore, we performed Optogenetics experiments in acute slices using these Pb exposed mice to determine if the hippocampus-PFC synapses were altered. Our preliminary results suggest that the synaptic strength and short-term synaptic depression are also altered by both high (N = 3) and low Pb (N = 2) levels at hippocampus-PFC synapses. Overall, these results contribute to better understand the long-term effects of low-level Pb exposure on learning and memory in children living in low-level environmental Pb.
Funder Acknowledgement(s): This research was supported by the Research Initiative for Scientific Enhancement Grant No. R25 GM 069621. We are extremely grateful that Dr. Christina Sobin generously gave us her mouse models of lead exposure to perform this study. This research was supported by a NIHfunded BBRC pilot project# 5G12MD007592-22.
Faculty Advisor: Karine Fenelon,