Effects of gold nanoparticles phytoreduced with L. extract on the aorta wall function in rats with hyperlipid diet - a study on isolated aortic rings.

Background: Vascular reactivity may be influenced by the dysfunction of the perivascular adipose tissue (PVAT) that occurs after a prolonged high fat diet (HFD).

Aim: The aim of this study was to investigate the vascular responses in rats with prolonged HFD after the administration of L. extract as a simple solution or as a reducing agent for gold nanoparticles (AuNPs).

Methods: Sprague-Dawley adult female rats (21 animals) were randomly allocated into three groups (n=7) and received for 9 months hyperlipid diet, the last month with treatment administered through oral gavage, 0.5 mL/day of solution as follows: HFD group - 0.9% saline solution, HFD+CM group - L. extract (0.158 mg/mL polyphenols), HFD+AuNPsCM group - gold nanoparticles phytoreduced with L. extract (AuNPsCM, 260 μg Au/kg/day). The Control group of rats (n=7) was fed with standard diet and in the last month received 0.9% saline solution as treatment. At the end of the experiment, the rats' descending aortas were collected and were used to investigate the aorta wall responses to vasoconstrictor (phenylephrine) and vasodilator (acetylcholine) substances added in tissue bath.

Results: AuNPsCM administration, compared to Control and HFD groups, increased the contraction and reduced the relaxation in aorta rings of rats with prolonged high-fat diet. The simple solution of L. extract produced contractile responses similar to those recorded in the Control group, at lower levels than in HFD group, and relaxation responses significantly decreased in comparison with Control group and significant increased when compared to HFD group.

Conclusions: L. extract administered as simple solution improved the aorta functions, while AuNPsCM solution enhanced the existed aorta wall modifications occurred after prolonged HFD, altering the vessel wall responses.