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Aging Cell. 2015 Aug;14(4):659-68. doi: 10.1111/acel.12345. Epub 2015 Apr 11.

Aging-associated formaldehyde-induced norepinephrine deficiency contributes to age-related memory decline.

Author information

1
Alzheimer's disease Center, Beijing Institute for Brain Disorders, Capital Medical University, Beijing, 100069, China.
2
Section of Environmental Biomedicine, Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Sciences, Central China Normal University, Wuhan, 430079, China.
3
Neuroscience Research Institute & Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, 100191, China.
4
Beijing Geriatric Hospital, Beijing, 100049, China.

Abstract

A norepinephrine (NE) deficiency has been observed in aged rats and in patients with Alzheimer's disease and is thought to cause cognitive disorder. Which endogenous factor induces NE depletion, however, is largely unknown. In this study, we investigated the effects of aging-associated formaldehyde (FA) on the inactivation of NE in vitro and in vivo, and on memory behaviors in rodents. The results showed that age-related DNA demethylation led to hippocampal FA accumulation, and when this occurred, the hippocampal NE content was reduced in healthy male rats of different ages. Furthermore, biochemical analysis revealed that FA rapidly inactivated NE in vitro and that an intrahippocampal injection of FA markedly reduced hippocampal NE levels in healthy adult rats. Unexpectedly, an injection of FA (at a pathological level) or 6-hydroxydopamine (6-OHDA, a NE depletor) can mimic age-related NE deficiency, long-term potentiation (LTP) impairments, and spatial memory deficits in healthy adult rats. Conversely, an injection of NE reversed age-related deficits in both LTP and memory in aged rats. In agreement with the above results, the senescence-accelerated prone 8 (SAMP8) mice also exhibited a severe deficit in LTP and memory associated with a more severe NE deficiency and FA accumulation, when compared with the age-matched, senescence-resistant 1 (SAMR1) mice. Injection of resveratrol (a natural FA scavenger) or NE into SAMP8 mice reversed FA accumulation and NE deficiency and restored the magnitude of LTP and memory. Collectively, these findings suggest that accumulated FA is a critical endogenous factor for aging-associated NE depletion and cognitive decline.

KEYWORDS:

formaldehyde; long-term potentiation; norepinephrine; senescence-accelerated prone 8; spatial memory; spontaneous discharge

PMID:
25866202
PMCID:
PMC4531079
DOI:
10.1111/acel.12345
[Indexed for MEDLINE]
Free PMC Article

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