Liver autofluorescence properties in animal model under altered nutritional conditions

Abstract

Autofluorescence spectroscopy is a promising and powerful approach for an in vivo, real time characterization of liver functional properties. In this work, preliminary results on the dependence of liver autofluorescence parameters on the nutritional status are reported, with particular attention to vitamin A and lipid accumulation in liver tissue. Normally fed and 24 h starving rats were used as animal models. Histochemical and autofluorescence analysis showed that lipids and vitamin A colocalize in the liver parenchyma. Fasting condition results in a parallel increase in both lipids and vitamin A. Autofluorescence imaging and microspectrofluorometric analysis carried out on unfixed, unstained tissue sections under 366 nm excitation, evidenced differences in both spectral shape and response to continuous irradiation between liver biopsies from fed and starving rats. As to photobleaching, in particular, fitting analysis evidenced a reduction of about 85% of the signal attributable solely to vitamin A during the first 10 s of irradiation. The tissue whole emission measured in fed and starving rat livers exhibited reductions of about 35% and 52%, respectively, that are closely related to vitamin A contents. The findings open interesting perspectives for the set up of an in situ, real time diagnostic procedure for the assessment of liver lipid accumulation, exploiting the photophysical properties of vitamin A.

Human liver autofluorescence: An intrinsic tissue parameter discriminating normal and diseased conditions

“…A good correlation is found between AF of vitamin A and NRfluorochromized lipids as to both fluorescence intensity and spatial distribution. These results are in agreement with previous findings on the direct relationship between localization and amount of vitamin A and lipids, in the parenchima of a rat model of liver lipid accumulation induced by acute starvation [24].…”

“…Vitamin A detection: performed by means of Gold chloride (GC) staining procedure [31], modified as already described [24]. Briefly Lipid detection: performed by means of Nile Red (NR) (Eastman Kodak Co., Rochester, NY) fluorochromization [32].…”

“…Taking advantage of its high-emission signal and strong photo-lability [23], vitamin A was proposed as a photo-physical marker for an in situ, real-time estimation of lipids [24].…”

Integrated Autofluorescence Characterization of a Modified-Diet Liver Model with Accumulation of Lipids and Oxidative Stress

“…In this respect, it is to take into account that only a part of lipids can give rise to a noticeable AF emission, obviously depending on lipid molecular features. Preliminary indications demonstrated that marked AF signals and photolability are exhibited by fatty acids such as arachidonic, linoleic, and stearic acids, while other derivatives such as butirric and palmitic acids, triglycerides, and phospholipids are in general poorly fluorescent ([22, 24, 47] and unpublished results). Further and complex studies would be however required to define more precisely the AF properties of the numerous lipid derivatives.…”

Oxygen tension-independent protection against hypoxic cell killing in rat liver by low sodium

“…The fixed tissue was embedded in paraplast and processed for light microscopy. 10 Non-viable cells were identified by trypan blue nuclear staining, in tissue sections stained with eosin or hematoxylin/eosin (E/E).…”