Genistein inhibits Aß25-35 -induced SH-SY5Y cell damage by modulating the expression of apoptosis-related proteins and Ca2+ influx through ionotropic glutamate receptors.

In this study, we investigated the protective effects of genistein against SH-SY5Y cell damage induced by ß-amyloid 25-35 peptide (Aß25-35 ) and the underlying mechanisms. Aß-induced neuronal death, apoptosis, glutamate receptor subunit expression, Ca2+ ion concentration, amino acid transmitter concentration, and apoptosis-related factor expression were evaluated to determine the effects of genistein on Aß-induced neuronal death and apoptosis. The results showed that genistein increased the survival of SH-SY5Y cells and decreased the level of apoptosis induced by Aß25-35 . In addition, genistein reversed the Aß25-35 -induced changes in amino acid transmitters, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors, and N-methyl-d-aspartate (NMDA) receptor subunits in SH-SY5Y cells. Aß25-35 -induced changes in Ca2+ and B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X (Bax) protein and gene levels in cells were also reversed by genistein. Our data suggest that genistein protects against Aß25-35 -induced damage in SH-SY5Y cells, possibly by regulating the expression of apoptosis-related proteins and Ca2+ influx through ionotropic glutamate receptors.

Zn2+ reduction induces neuronal death with changes in voltage-gated potassium and sodium channel currents.

In the present study, cultured rat primary neurons were exposed to a medium containing N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), a specific cell membrane-permeant Zn2+ chelator, to establish a model of free Zn2+ deficiency in neurons. The effects of TPEN-mediated free Zn2+ ion reduction on neuronal viability and on the performance of voltage-gated sodium channels (VGSCs) and potassium channels (Kvs) were assessed. Free Zn2+ deficiency 1) markedly reduced the neuronal survival rate, 2) reduced the peak amplitude of INa, 3) shifted the INa activation curve towards depolarization, 4) modulated the sensitivity of sodium channel voltage-dependent inactivation to a depolarization voltage, and 5) increased the time course of recovery from sodium channel inactivation. In addition, free Zn2+ deficiency by TPEN notably enhanced the peak amplitude of transient outward K+ currents (IA) and delayed rectifier K+ currents (IK), as well as caused hyperpolarization and depolarization directional shifts in their steady-state activation curves, respectively. Zn2+ supplementation reversed the effects induced by TPEN. Our results indicate that free Zn2+ deficiency causes neuronal damage and alters the dynamic characteristics of VGSC and Kv currents. Thus, neuronal injury caused by free Zn2+ deficiency may correlate with its modulation of the electrophysiological properties of VGSCs and Kvs.

An in situ crosslinked compression coat comprised of pectin and calcium chloride for colon-specific delivery of indomethacin.

The use of pectin for colon-specific drug delivery has been extensively investigated; however, when used alone, pectin is often compromised due to its high solubility. This study explored the feasibility of using an in situ compression-coated crosslinking system, composed of pectin and calcium chloride, for colon-specific drug delivery. A pectin/calcium chloride (P/Ca) coating was compressed onto a core tablet. The colon specificity of the compression-coated tablet was verified by dissolution, pharmacokinetics and scintigraphy with (99m)Tc labeling. The in situ pectin and calcium chloride gel slowed the release of indomethacin. The lag time varied between 3 h and 7 h depending on the amount of calcium chloride and the coating weight. Pectinase triggered the release of indomethacin from the compression-coated tablet, which was then accelerated by the calcium chloride in the coating layer. The compression-coated tablet had a prolonged tmax and apparent t1/2, as well as a decreased Cmax and AUC0-t, compared with the core tablet counterpart. Evaluation with γ-scintigraphy verified colon-specific delivery of the compression-coated tablet. In conclusion, the P/Ca in situ crosslinking system worked well for colon-specific drug delivery.

Development of a reservoir-type transdermal delivery system containing eucalyptus oil for tetramethylpyrazine.

The purpose of this study was to formulate a reservoir-type transdermal delivery system (TDS) for 2,3,5,6-tetramethylpyrazine (TMP) to enable the delivery of a sufficient dose through human skin to achieve an effective therapeutic plasma concentration. To improve the penetration of TMP in the reservoir-type TDS, several chemical penetration enhancers were investigated using in vitro rat dorsal skin permeation studies. Eucalyptus oil was found to enhance the permeation of TMP to the greatest extent, with the optimal concentration being 5% and the flux being 542.6 ± 49.7 µg/cm(2)/h, which was 4.5-fold greater than control with no enhancer (p < 0.01). The flux of the optimized reservoir-type TDS permeated through the human epidermis was 346.0 ± 27.7 µg/cm(2)/h. Based on the in vitro human skin permeation flux and the pharmacokinetics parameters observed, the clinical surface area of the TDS patch was predicted to be 20 cm(2). The in vivo study conducted in rabbits showed that the TMP TDS patch containing 5% eucalyptus oil had a more favorable pharmacokinetic profile, with a lower C(max) and prolonged T(max) and mean residence time than that observed with the oral administration of TMP. The TMP reservoir-type TDS was shown to be a promising alternative route to oral administration or intravenous infusion of TMP.

In vitro evaluation and pharmacokinetics in dogs of guar gum and Eudragit FS30D-coated colon-targeted pellets of indomethacin.

A pH- and enzyme-dependent colon-targeted multi-unit delivery system of indomethacin was developed by coating guar gum and Eudragit FS30D sequentially onto drug-loaded pellets in a fluidized bed coater. In vitro studies showed that smaller coating weight gain of guar gum resulted in reduced release lag time t10 (10% release time), but favored degradation by enzymes (galactomannanase). A cumulative weight gain (CWG) of 44% provided sufficient enzymatic sensitivity and protection of the core. Under gradient pH conditions (pH = 1.2, 6.8, 7.4 and 6.5 for 2, 2, 1 and 15 h, respectively), indomethacin was released from Eudragit FS30D-coated pellets quickly after changing pH to 7.4. For guar gum/Eudragit FS30D double-coated pellets, only about 5% of the drug was released after another 1 h, showing retarding effect by guar gum coating. After changing pH to 6.5 and addition of galactomannanase, enzyme-dependent drug release was observed. Pharmacokinetic study in beagle dogs showed that fastest absorption with the smallest Tmax and Tlag was observed for uncoated pellets. The Tmax and Tlag of Eudragit FS30D-coated pellets were postponed to about 2.5 and 1 h, respectively. After a further guar gum coating, Tlag was further postponed to about 2.8 h, about 2 h of additional lag time on the basis of Eudragit FS30D coating. It is indicated that the guar gum/Eudragit FS30D-coated system has potential to be used to deliver drugs to the colon.