Eucalyptus Leaf Extract Suppresses the Postprandial Elevation of Portal, Cardiac and Peripheral Fructose Concentrations after Sucrose Ingestion in Rats

Overintake of sucrose or fructose induces adiposity. Fructose undergoes a strong Maillard reaction, which worsens diabetic complications. To determine whether Eucalyptus globulus leaf extract (ELE) suppresses the postprandial elevation of serum fructose concentrations (SFCs) in the portal, cardiac, and peripheral blood after sucrose ingestion, we performed gas chromatography/mass spectrometry (GC/MS) and measured SFC without any interference by contaminating glucose in the samples. Fasting Wistar rats were orally administered water (control group) or ELE (ELE group) before sucrose ingestion. Blood was collected from the portal vein, heart, and tail. The increase in the SFCs in the portal and cardiac samples 30 min after sucrose ingestion was lower in the ELE group than in the control group. The coefficient of correlation between the SFCs in the portal and cardiac samples was 0.825. The peripheral SFC in the control group progressively increased and was 146 µmol/L at 60 min. This increase was significantly lower in the ELE group. In contrast, the serum glucose concentrations in the 2 groups were similar. ELE suppressed postprandial hyperfructosemia in the portal, cardiac, and peripheral circulations. ELE may counteract glycation caused by high blood fructose concentrations induced by the consumption of fructose-containing foods or drinks

The Role of a Brain-specific Splice Variant of Ryanodine Receptor Type 1

The ryanodine receptor type 1 (RyR1) is capable of homotetrameric assembly to form a Ca2+ release channel at intracellular Ca2+ storage sites such as endoplasmic reticulum (ER). The mRNA transcript encoding full-length RyR1 is approximately 16kb and is mainly distributed in excitable cells. A 2.4-kb mRNA splice variant from the 3\u27-terminal region of the RyR1 gene coexists specifically in brain together with the full-length form, although the functions of this brain-specific splice variant remain unclear. To investigate the short form of RyR1 in intracellular Ca2+ signaling in brain at the cellular level, we established an experimental system whereby the green fluorescent protein (GFP) -tagged brain-specific variant of RyR1 is coexpressed with the full-length protein in the same cell. Both forms of RyR1 were localized in the ER. Caffeine-induced Ca2+-release activities in cells expressing both the brain-specific and full-length RyR1 were reduced compared to cells expressing only the full-length form of RyR1. These results suggested that coexpression of the brain-specific splice variant of RyR1 with its full-length counterpart modulates intracellular Ca2+ signaling by acting as a dominant-negative subunit of the Ca2+ release channel in a tissue-specific fashion