title: Analytical evidence of heterogeneous lead accumulation in the hypothalamic defence area and nucleus tractus solitarius.
abstract: Lead is a potent toxicant associated with adverse cardiovascular effects and hypertension in children. Yet, few studies have determined if autonomic dysfunction associated with lead exposure involves brain regions which regulate autonomic responses. Central autonomic nuclei such as the nucleus tractus solitarius (NTS) and hypothalamic defence area (HDA) may be particularly sensitive to lead infiltration because they are adjacent to ventricles and areas with semi-permeable blood-brain-barriers. To understand if autonomic nuclei are sensitive to lead accumulation Wistar rats were exposed to lead from the gestational period and lead levels were quantified in brain regions that regulate arterial pressure: the NTS and the HDA. Energy dispersive X-ray fluorescence (EDXRF) was used to quantify total brain lead levels and revealed no differences between exposed and control tissues; measured values were close to the detection limit (2μg/g). Electrothermal atomic absorption spectrometry (ETAAS) was also used, which has a greater sensitivity, to quantify lead. There was ∼2.1μg/g lead in the NTS and ∼3.1μg/g lead in the HDA of exposed rats, and no lead in the control rats. There were greater lead levels in the HDA (∼50%) as compared with the NTS. Pathology studies revealed more prominent lead granules in the HDA as compared with the NTS. Increased microglia and astrocyte activation was also noted in the NTS of lead exposed rats as compared with the HDA. Regional differences in neuro-inflammatory responses likely contribute to heterogeneous lead accumulation, with enhanced clearance of lead in the NTS. Future studies will resolve the mechanisms underpinning tissue-specific lead accumulation.
authors.affiliation: Centro de Física Atómica da Universidade de Lisboa, Departamento de Física, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal; Laboratory of Inorganic and Nuclear Chemistry, Wadsworth Center, New York State Department of Health, PO Box 509, Albany, NY 12201-0509, USA. Electronic address: diana.guimaraes@health.ny.gov.
authors.forename: D
authors.initials: D
authors.lastname: Guimarães
authors.affiliation: Centro de Física Atómica da Universidade de Lisboa, Departamento de Física, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: J P
authors.initials: JP
authors.lastname: Santos
authors.affiliation: Centro de Física Atómica da Universidade de Lisboa, Departamento de Física, Faculdade de Ciências e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors.forename: M L
authors.initials: ML
authors.lastname: Carvalho
authors.affiliation: REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologias da Universidade Nova de Lisboa, 2829-516 Monte da Caparica, Portugal.
authors.forename: M S
authors.initials: MS
authors.lastname: Diniz
authors.affiliation: School of Public Health, State University of New York, Wadsworth Center, Empire State Plaza, Albany, NY 12201-0509, USA; Molecular Toxicology, Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12201-0509, USA.
authors.forename: B
authors.initials: B
authors.lastname: House
authors.affiliation: Molecular Toxicology, Wadsworth Center, New York State Department of Health, Empire State Plaza, Albany, NY 12201-0509, USA; School of Public Health, State University of New York, Wadsworth Center, Empire State Plaza, Albany, NY 12201-0509, USA.
authors.forename: V M
authors.initials: VM
authors.lastname: Miller
mesh_terms: D000818:Animals; D001341:Autonomic Nervous System / Q000737:chemistry; D001923:Brain Chemistry; D005260:Female; D007031:Hypothalamus / Q000737:chemistry*; D007854:Lead / Q000008:administration & dosage / Q000032:analysis*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D017552:Solitary Nucleus / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013054:Spectrophotometry, Atomic
chemical_list: D007854:Lead
keywords: Autonomic; Electrothermal atomic absorption spectrometry (ETAAS); Hypothalamic defence area (HDA); Lead; Neuroinflammation; Nucleus tractus solitarius (NTS)