title: Brain Formaldehyde is Related to Water Intake behavior.
abstract: A promising strategy for the prevention of Alzheimer's disease (AD) is the identification of age-related changes that place the brain at risk for the disease. Additionally, AD is associated with chronic dehydration, and one of the significant changes that are known to result in metabolic dysfunction is an increase in the endogenous formaldehyde (FA) level. Here, we demonstrate that the levels of uric formaldehyde in AD patients were markedly increased compared with normal controls. The brain formaldehyde levels of wild-type C57 BL/6 mice increased with age, and these increases were followed by decreases in their drinking frequency and water intake. The serum arginine vasopressin (AVP) concentrations were also maintained at a high level in the 10-month-old mice. An intravenous injection of AVP into the tail induced decreases in the drinking frequency and water intake in the mice, and these decreases were associated with increases in brain formaldehyde levels. An ELISA assay revealed that the AVP injection increased both the protein level and the enzymatic activity of semicarbazide-sensitive amine oxidase (SSAO), which is an enzyme that produces formaldehyde. In contrast, the intraperitoneal injection of formaldehyde increased the serum AVP level by increasing the angiotensin II (ANG II) level, and this change was associated with a marked decrease in water intake behavior. These data suggest that the interaction between formaldehyde and AVP affects the water intake behaviors of mice. Furthermore, the highest concentration of formaldehyde in vivo was observed in the morning. Regular water intake is conducive to eliminating endogenous formaldehyde from the human body, particularly when water is consumed in the morning. Establishing good water intake habits not only effectively eliminates excess formaldehyde and other metabolic products but is also expected to yield valuable approaches to reducing the risk of AD prior to the onset of the disease.
authors.affiliation: 1State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; 6University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Li
authors.affiliation: 1State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Su
authors.affiliation: 1State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Yingge
authors.initials: Y
authors.lastname: He
authors.affiliation: 5Beijing Geriatric Hospital, Beijing 100095, China.
authors.forename: Jihui
authors.initials: J
authors.lastname: Lu
authors.affiliation: 1State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Weichuan
authors.initials: W
authors.lastname: Mo
authors.affiliation: 1State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; 3Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wei
authors.affiliation: 1State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; 2Alzheimer's Disease Center, Beijing Institute for Brain Disorders, Capital Medical University, Beijing 100069, China; 4Southwest Medical University, Sichuan 646000, China.
authors.forename: Rongqiao
authors.initials: R
authors.lastname: He
keywords: arginine vasopressin; behavior; formaldehyde; semicarbazide-sensitive amine oxidase; water intake