title: Molecular changes underlying reduced pineal melatonin levels in Alzheimer disease: alterations in preclinical and clinical stages.
abstract: A disturbed sleep-wake rhythm is common in Alzheimer disease (AD) patients and correlated with decreased melatonin levels and a disrupted circadian melatonin rhythm. Melatonin levels in the cerebrospinal fluid are decreased during the progression of AD neuropathology (as determined by the Braak stages), already in cognitively intact subjects with the earliest AD neuropathology (Braak stages I-II) (preclinical AD). To investigate the molecular mechanisms behind the decreased melatonin levels, we measured monoamines and mRNA levels of enzymes of the melatonin synthesis and its noradrenergic regulation in pineal glands from 18 controls, 33 preclinical AD subjects, and 25 definite AD patients. Pineal melatonin levels were highly correlated with cerebrospinal fluid melatonin levels. The circadian melatonin rhythm disappeared because of decreased nocturnal melatonin levels in both the preclinical AD and AD patients. Also the circadian rhythm of beta(1)-adrenergic receptor mRNA disappeared in both patient groups. The precursor of melatonin, serotonin was stepwise depleted during the course of AD, as indicated by the up-regulated monoamine oxidase A mRNA and activity (5-hydroxyindoleacetic acid:serotonin ratio). We conclude that a dysfunction of noradrenergic regulation and the depletion of serotonin by increased monoamine oxidase A result in the loss of melatonin rhythm already in preclinical AD.
authors.affiliation: Anhui Geriatric Institute, First Affiliated Hospital of Anhui Medical University, Hefei 230022, Anhui People's Republic of China.
authors.forename: Ying-Hui
authors.initials: YH
authors.lastname: Wu
authors.forename: Matthijs G P
authors.initials: MG
authors.lastname: Feenstra
authors.forename: Jiang-Ning
authors.initials: JN
authors.lastname: Zhou
authors.forename: Rong-Yu
authors.initials: RY
authors.lastname: Liu
authors.forename: Javier Sastre
authors.initials: JS
authors.lastname: Toranõ
authors.forename: Hendrikus J M
authors.initials: HJ
authors.lastname: Van Kan
authors.forename: David F
authors.initials: DF
authors.lastname: Fischer
authors.forename: Rivka
authors.initials: R
authors.lastname: Ravid
authors.forename: Dick F
authors.initials: DF
authors.lastname: Swaab
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000134:cerebrospinal fluid / Q000378:metabolism* / Q000503:physiopathology; D016022:Case-Control Studies; D002940:Circadian Rhythm; D004298:Dopamine / Q000378:metabolism; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D008550:Melatonin / Q000096:biosynthesis / Q000134:cerebrospinal fluid / Q000378:metabolism*; D008995:Monoamine Oxidase / Q000235:genetics; D009638:Norepinephrine / Q000378:metabolism; D010870:Pineal Gland / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D018342:Receptors, Adrenergic, beta-1 / Q000235:genetics; D012701:Serotonin / Q000378:metabolism
chemical_list: D012333:RNA, Messenger; D018342:Receptors, Adrenergic, beta-1; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D008995:Monoamine Oxidase; D008550:Melatonin; D004298:Dopamine; D009638:Norepinephrine