Cross-talk between 5-hydroxytryptamine and substance P in the melanogensis and apoptosis of B16F10 melanoma cells.

Skin pigmentation is a complex process controlled by many different factors. Substance P (SP) regulates many biological functions, including melanogenesis and stress. Our previous study indicated that regulation of SP on melanocyte function was mediated by neurokinin 1 receptor (NK1 receptor). Substantial evidence has accumulated that psychological stress can be associated with skin pigmentation, so that the impact of 5-hydroxytryptamine (5-HT), one of the important factors participating in stress process, on melanogenesis has also been concerned. It has been reported that 5-HT induces melanin synthesis via 5-HT2A receptor. Furthermore, 5-HT2A receptor and NK1 receptor are G-protein coupled receptors (GPCRs) and both expressed on melanocyte, the present study was designed to investigate whether SP has influence on the adjustment function of 5-HT. Our data demonstrated that, SP inhibited 5-HT2A receptor expression to neutralize the pro-melanogenesis effect of 5-HT on B16F10 cells. The up-regulation of NK1 receptor expression was simultaneous with the down-regulation of 5-HT2A receptor treated by SP. This inhibition of 5-HT2A receptor expression by SP could be reversed by NK1 receptor antagonist Spantide I. Our studies indicated that SP could directly induce B16F10 cells apoptosis in vitro. 5-HT and 5-HT2A receptor agonist could mitigate this apoptotic effect of SP. It is the strong evidence of possible cross-talk between GPCRs and giving enlightenments when screening desirable drugs for target receptors.

Characterization, biodistribution and targeting evaluation of breviscapine lipid emulsions following intravenous injection in mice.

Breviscapine lipid emulsions were prepared by a high speed dispersion-homogenization method with optimal formulation and technological method. The proportion of liposomes in breviscapine lipid emulsions, an important character for determining the behavior of drug in vivo belongs to which carriers, was less than 5%. Loading breviscapine into lipid emulsions did increase the breviscapine concentrations in plasma, retarded the clearance, and exhibited the properties of sustained-release concluded by pharmacokinetic parameters: after bolus administration, the elimination phase (t(1/2(ß)) = 99.535) of lipid emulsions was 5.4-times longer than that of Injectio Breviscapine. The AUC(0→∞) (14.453-times), k(10) (0.047-times), Cl(s) (0.147-times), and MRT(0→∞) (17.766-times) values also confirmed this trend. The amount of drug in every tissue increased at different levels after intravenous administration of breviscapine lipid emulsions compared with Injectio Breviscapine. The relative exposure value of breviscapine lipid emulsions for plasma and lungs were 29.59 and 5.81, respectively, indicating that the exposure of breviscapine to plasma and lungs was significantly increased by entrapment in lipid emulsions. Other targeting evaluation indexes also proved the superiority of lipid emulsions carrier to deliver drug to the targeting region of vascular and lung diseases therapy.

Optimized preparation, characterization and biodistribution in heart of breviscapine lipid emulsion.

Breviscapine is a Traditional Chinese Medicine treating cardiovascular diseases by promoting blood circulation and removing blood stasis. The major active component of breviscapine has low aqueous solubility, poor chemical stability, short biological half-life and rapid elimination rate from the plasma. The use of a lipid emulsion formulation containing breviscapine might improve chemical stability, increase drug loading, exhibit sustained release profile. In the present study, we developed an optimized formulation and technological method for the preparation of sterile and stable breviscapine lipid emulsion (Bre-LE) for intravenous infusion. The average particle size, polydispersity index, zeta potential, stability constant (K(s)) value and content of final product were (225.3±8.8) nm, 0.221±0.020, (-29.6±1.5) mV, (24.3±2.9)% and (94.5±0.6)% respectively (n=3). The results of in vitro release experiment suggest that lipid emulsion as breviscapine carrier showed a desirable sustained release profile. Dilution stability and long-term stability were also researched in the present paper. The results show the carrier could protect drug from degradation after dilution by phosphate buffered saline and fetal calf serum. And Bre-LE was stable for up to 6 months at room temperature storage condition. The biodistribution of drug in heart of mice increased dramatically after encapsulation into lipid emulsion which was beneficial to heart disease therapy.