Heat stress can stimulate an increase in body temperature, which is correlated with increased expression of heat shock protein 70 （HSP70） and tumor necrosis factor a （TNFa）. The exact mechanism underlying the HSP70 and TNFa induction is unclear. Berberine （BBR） can significantly inhibit the temperature rise caused by heat stress, but the mechanism responsible for the BBR effect on HSP70 and TNFa signaling has not been investigated. The aim of the present study was to explore the relationship between the expression of HSP70 and TNFa and the effects of BBR under heat conditions, using in vivo and in vitro models. The expression levels of HSP70 and YNFa were determined using RT-PCR and Western blotting analyses. The results showed that the levels of HSP70 and TNFa were ap-regulated under heat conditions （40 ~C）. HSP70 acted as a chaperone to maintain TNFa homeostasis with rising the temperature, but knockdown of HSP70 could not down-regulate the level of TNFa. Furthermore, TNFa could not influence the expression of HSP70 under aormal and heat conditions. BBR targeted both HSP70 and TNFa by suppressing their gene transcription, thereby decreasing body temperature under heat conditions. In conclusion, BBR has a potential to be developed as a therapeutic strategy for suppressing the thermal effects in hot environments.
Berberine （BBR） has a variety of pharmacological activities. Studies have reported that BBR not only reduces heat stress-induced fever but also inhibits lower body temperatures due to cold stress. Heat stress can be reduced via BBR treatment, which antagonizes HSP70-TNFa to regulate the body temperature alteration. In cold stress, however, the molecular mechanism of BBR-induced inhibition of hypothermia remains unclear. Therefore, we studied whether BBR promoted uncoupling protein 1 （UCP1, a crucial protein of thermogenesis） expression and its mechanism under cold stress. Wild type mice and Ucpl-/- mice were used for the in vivo experiments, and primary brown adipocytes and brown adipocytes HIB-1B were used for the in vitro studies. The cold stress was set at 4℃. The results showed that at 4℃, the body temperature of mice was decreased. BBR effectively inhibited this hypothermia. Simultaneously, Ucpl expression in brown adipose tissue （BAT） cells was significantly increased, and BBR promoted Ucpl expression. However, in Ucpl-knockout mice, the effect of BBR on hypothermia disappeared during cold stress, indicating that the main target for BBR regulation of body temperature was Ucpl. Further studies showed that the transcriptional response element NFE2 （nuclear factor erythroid-derived 2） in the upstream of the Ucpl promoter region contributed to the positive regulatory role on Ucpl expression at lower temperature. BBR could bind to the sequence of NFE2 response element in a temperature-dependent manner. Increased affinity of BBR binding to NFE2 response element in cold stress significantly strengthened and enhanced the expression of Ucpl. This work was important for understanding the role of BBR on thermogenesis in BAT, body temperature regulation and temperature tolerance under cold conditions.
A simple, reliable, economical method was developed using HPLC with a diode-array detector for determination of total flavonoids in plasma after introvenous administration of ginkgo biloba extract. The method simultaneously detects quercetin, kaempferol, and isorhamnetin after acid hydrolysis and recalcula- tion. The hydrolysis and extraction conditions were optimized in an orthogonal test. The specificity was tested by comparing the retention time, UV spectra, and peak purity indices with standards. The detection limits were 20 ng/mL for quercetin, 20 ng/mL for kaempferol, and 50 ng/mL for isorhamnetin. The calibration curve ranges were 75-2400, 71-2280, and 70-2240 ng/mL. The pharmacokinetic characteristics of ginkgo biloba flavonoids after venous administration of 50 mg/kg ginkgo biloba extract to rats were analyzed using a two-compartment model. The initial plasma concentration was 171.22 μg/mL. The half-life of flavonoids in the first compartment （distribution） was 0.07 h and at the second compartment （elimination） was 4.51 h, while the AUC（0-∞） was 1711.06 Iag-min/mL. The apparent volume of distribution was 0.11 L/kg. The total body clearance is 10.52 mL/（min.kg）. The result shows the method is suitable for pharmacokinetic studies.
Corticosterone, a principal glucocorticoid synthesized in the rodent adrenal cortex, can be cumula- tively toxic to hippocampal neurons, the cause of which is not known. The present study determined whether the cytosol adenylate kinase （AK） system long-term exposure to high corticosterone levels. We was involved in the neuronal damage induced by nvestigated the effects of long-term exposure to high corticosterone levels on AK1 activity, AK1 mRNA expression, and energy levels in cultured hippocampal neurons. The results show that long-term exposure to high corticosterone levels induces a reduction of the cultured hippocampal neuron viability, significantly reduces energy levels, and causes a time-dependant re- duction of the AK1 activity. These findings indicate that changes in the AK system might be the mechanism underlying neuronal damage induced by long-term exposure to high corticosterone levels.
Berberine, an isoquinoline alkaloid component of Rhizoma Coptidis has been demonstrated to be the key active ingredient involved in its protective effect against cerebral ischemia-reperfusion. However, the comparison among the analogues to the protective effect against oxygen and glucose deprivation/reoxygenation （OGD-R） was mediated by inhibition of cyclooxygenase-2 （COX-2） has never been reported. The aim of this study is to investigate the protective effect of berberine and its five analogues against OGD-R in PC 12 cells, as well as to determine whether the protective effect was regulated through COX-2. An established in vitro OGD-R model of PC12 cells by oxygen glucose deprivation of 4 h and reperfusion of 24 h was used in our study. After cells were treated with berberine or its five analogues, we examined the cell viability assay by 3-（4,5-dimethylthiazol-2-yl）-2,5- diphenyltetrazolium bromide （MTT） assay. Cells were also collected to determine the levels of mRNA and protein of COX-2 by real time PCR and Western blot. We found that berberine and its analogues improved the viability of PC12 cells against OGD-R. Whereas berberine and berberrubine presented stronger activity with the most effective dose of 0.31 lag/mL and the minimum effective doses of 0.02 and 0.04 gg/mL. Palmatine possessed potentially weaker protective effect. The mRNA level of COX-2 in cells treated with berberine, coptisine and epiberberine was decreased significantly. The protein level of COX-2 was significantly down-regulated in cells treated with berberine. Studies suggested the important role of methylenedioxy groups （R2 and R3） of berberine analogues in COX-2 inhibitory effect, and methylenedioxy groups （R2, R3, R9 and R10） in berberine analogues in binding affinity with COX-2. Substituted hydroxyl group at R9 did not affect the activity of berberine. In summary, our study illustrated the protective effects of berberine and its analogues in PCI2 cells against OGD-R and to elucidate the structure-activity relat
