title: Conformational properties of serum albumin binding sites in rats with different behaviour in the open field test.
abstract: In this study, the hypothesis was tested that behaviour of rats under the open field test condition and effects of subsequent acute stress relate to conformational properties of the main plasma carrier protein, albumin.To evaluate albumin properties, fluorescence intensity of a molecular probe CAPIDAN (N-carboxyphenylimide of dimethylaminonaphthalic acid) at N (at pH 7.4) and F (at pH 4.2) albumin conformations was measured and the N-F signal ratio was calculated. The data obtained showed that CAPIDAN fluoresces selectively from albumin in rat serum and its fluorescence is sensitive to binding of fatty acids and some other ligands to albumin. Behaviour of 78 Wistar male rats was characterized from the fraction of time taken for exploratory and ambulatory activity during the open field test. In rats not subjected to stress (n = 40), a negative correlation was revealed between open field activity and CAPIDAN N-to-F ratio for albumin (r = - 0.55, p < 0.0005). In the group of rats subjected to acute stress (immobilization plus stochastic electrocutaneous stimulation) the correlation between behavioural activity and the albumin conformational properties was significantly positive (r = 0.59, p < 0.0001): the CAPIDAN albumin fluorescence ratio increased in the highly active rats and decreased in the low-activity rats. The mechanisms of the observed effects may involve differences in nonesterified fatty acid production during stress.
authors.affiliation: Department of Biophysics, Research Institute for Physical Chemical Medicine, 1-A Malaya Street, Moscow 119992, Russia. gryzunov@mail.ru
authors.forename: Yu A
authors.initials: YA
authors.lastname: Gryzunov
authors.forename: E V
authors.initials: EV
authors.lastname: Koplik
authors.forename: N V
authors.initials: NV
authors.lastname: Smolina
authors.forename: L B
authors.initials: LB
authors.lastname: Kopaeva
authors.forename: G E
authors.initials: GE
authors.lastname: Dobretsov
authors.forename: K V
authors.initials: KV
authors.lastname: Sudakov
mesh_terms: D000818:Animals; D001665:Binding Sites; D004558:Electric Stimulation; D005106:Exploratory Behavior / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005456:Fluorescent Dyes; D007094:Imides; D008297:Male; D015335:Molecular Probes; D009043:Motor Activity / Q000502:physiology; D009281:Naphthalenes; D011487:Protein Conformation; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical; D012709:Serum Albumin / Q000737:chemistry*; D013315:Stress, Psychological / Q000503:physiopathology*
chemical_list: D005230:Fatty Acids, Nonesterified; D005456:Fluorescent Dyes; D007094:Imides; D015335:Molecular Probes; D009281:Naphthalenes; D012709:Serum Albumin; C511435:dimethylaminonaphthalic acid N-carboxyphenylimide