High turnover rate of central histaminergic system in patients with Down syndrome and Alzheimer disease

Maria Concetta Gueli

Risultato della ricerca: Other

Abstract

HIGH TURNOVER RATE OF CENTRAL HISTAMINERGIC SYSTEM INPATIENTS WITH DOWN SYNDROME AND ALZHEIMER DISEASEMaria Concetta GueliDipartimento di Biomedicina Sperimentale e Neuroscienze Cliniche (BioNEC),Università degli Studi di PalermoIt is well confirmed that a strong relationship exists between Down’s syndrome (DS)and Alzheimer’s disease (AD). Neurochemical investigations reported that many centralneurotransmitter systems are similarly affected in aging Down and in Alzheimerpatients, respectively. Airaksinem et al. (1) found numerous neurofibrillary tangles inthe tuberomammillary area of the hypothalamus, where cell bodies of histaminergicneurons are located. While Mazurkiewicz-Kwilecki et al. (2) found deficits of theendogenous diamine, Cacabelos et al. (3) reported an increase of central histaminelevels. In the present study, in order to test whether AD-like neuropathological changesinvolve the central histaminergic system, we measured the concentration of histamine,histidine as well as the activity of histidine decarboxylase (HDC) and histamine-Nmethyltransferase(HMT) in temporal cortex (TC) of aging Down, Alzheimer andcontrol patients.Post-mortem samples (temporal cortex, TC; grey matter) of AD neuropathologicallyconfirmed cases (72.1 ± 7.6 years old), of karyotyped patients with DS (56.1 ± 7.1 yearsold), and control adults (72,7 ± 9.7 years old) were obtained from the MRC LondonBrain Bank for Neurodegenerative Diseases, Department of Neuropathology, Instituteof psychiatry, London, U.K.Each block of brain tissue from AD, DS and controls were thawed on ice andhomogenized in ice-cold HDC-solution of 0.1 M sodium phosphate buffer (pH 6.8)containing dithiothreitol and antipain protease inhibitor. Homogenates of brainspecimens were centrifuged at 12,000 x g for 20 min at 4°C. The supernatants werepoured into CENTRIPEP-3 concentrators (Amicon), and centrifuged at 2,000 x g fortwo 10 min periods at 4°C. The clear extracts were stored in small quantities inEppendorf tubes at -80°C until analysis. HDC activity has been measured with theprocedure described by Gueli et al. (4) and briefly summarized. Extract aliquots werepre-incubated for 10 min with HDC assay-solution (0.1 M PBS, 0.2 mM DTT, 0.01 mMPLP, 0.1 mM Aminoguanidine), then incubation was started by adding 0.5 mM Lhistidinefor 0-3 h at 37°C. At the established times, the reactions were stopped with 60% ice-cold PCA, and stored overnight. Finally, the reaction mixture was centrifuged at19,000 x g for 30 min at 4°C. The supernatants were withdrawn and filtered (0.45 mmMillipore filter). The HPLC system consisted of a 600E Waters pump with a Waters474 scanning fluorescence detector (ex 350 nm, em 450 nm). Chromatograms andcalculations were performed by Empower TM2 Data Software. Histamine wasseparated and quantified after pre-column derivatization with Shore’s o-phthalaldehydereaction (5), using a Spherisorb ODS2 analytical column, particle size 3 mm (20 x 0.46cm,) (Waters, Milano), a 10 L injection volume, and a mobile phase of methanol, 20mmol/ L sodium acetate in water, acetic acid (55:43:2 v/v) and 0.33 mmol/L 1-octanesulfonic acid sodium salt. The flow rate was 1.0 ml/min. In order to measureHMT activity brain tissue was disperged with a glass Teflon homogenizer in 0.1 M PBS(pH 7.2). After centrifugation the supernatant was used for the radioenzymatic assay(6). Histidine contents were measured using the procedure described by Borum (7).We observed a increase of histamine levels in temporal cortex of AD (+15%) patients.Down brains also showed a mild increase of the endogenous diamine
Lingua originaleEnglish
Pagine143-144
Numero di pagine2
Stato di pubblicazionePublished - 2013
Pubblicato esternamenteYes

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