Transitory glutathione deficit during brain development induces cognitive impairment in juvenile and adult rats: relevance to schizophrenia

Glutathione (GSH) metabolism dysfunction is one risk factor in schizophrenia. A transitory brain GSH deficit was induced in Wistar (WIS) and mutant (ODS; lacking ascorbic acid synthesis) rats using BSO (l-buthionine-(S,R)-sulfoximine) from post-natal days 5-16. When GSH was re-established to physiological levels, juvenile BSO-ODS rats were impaired in the water maze task. Long after treatment cessation, adult BSO-WIS/-ODS rats showed impaired place discrimination in the homing board with distributed visual or olfactory cues. Their accuracy was restored when a single cue marked the trained position. Similarly, more working memory errors were made by adult BSO-WIS in the radial maze when several olfactory cues were present. These results reveal that BSO rats did not suffer simple sensory impairment. They were selectively impaired in spatial memory when the task required the integration of multimodal or olfactory cues. These results, in part, resemble some of the reported olfactory discrimination and cognitive impairment in schizophrenia.     

Role of antioxidants in the O-hydroxyethyl-D-(Ser)8-cyclosporine A (SDZ IMM125)-induced apoptosis in rat hepatocytes

The mechanisms underlying the apoptotic activity of the immunosuppressive drug cyclosporine A and its O-hydroxyethyl-D-(Ser)(8)-derivative SDZ IMM125 in rat hepatocytes are not yet fully understood. It was the purpose of the present study to investigate the role of anti- and pro-oxidants and of caspase-3 and intracellular Ca(2+) in SDZ IMM125-induced apoptosis in rat hepatocytes. SDZ IMM125 induced an increase in chromatin condensation and fragmentation, and the activation of caspase-3. Supplementing the cell cultures with the antioxidants, D,L-alpha-tocopherol-polyethylene-glycol-1000-succinate, ascorbic acid, and the reducing agent, dithiothreitol, significantly inhibited the SDZ IMM125-mediated increase in chromatin condensation and fragmentation, and caspase-3 activity. D,L-alpha-tocopherol-polyethylene-glycol-1000-succinate and dithiothreitol caused significant inhibition on SDZ IMM125-mediated cellular Ca(2+) uptake. The glutathione synthetase inhibitor, buthionine sulfoximine, increased SDZ IMM125-mediated caspase-3 action in parallel to chromatin condensation and fragmentation as well as Ca(2+) influx. Supplementation the culture medium with the intracellular Ca(2+) chelator bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid as well as omission of calcium in the medium reduced SDZ IMM125-induced apoptosis whereas the calcium supplementation of the culture medium elevated SDZ IMM125-induced apoptosis. Calcium antagonists inhibited SDZ IMM125-induced caspase-3 activation. Our data indicate that SDZ IMM125-mediated apoptosis in rat hepatocytes can be inhibited by antioxidants, and that the intracellular redox-state can act as a modulator of cytotoxicity and apoptosis. Further, the results suggest that SDZ IMM125-induced uptake of extracellular calcium is also a redox-sensitive process and that the increased intracellular calcium might directly cause apoptosis by increasing the caspase-3 activity as a central event in the cyclosporine-induced apoptotic mechanism.     

高效液相色谱法测定丁磺氨酸及其胶囊的含量

目的建立丁磺氨酸(BSO)及其胶囊的含量测定方法。方法以2,4-二硝基氟苯为柱前衍生化试剂,反相高效液相色谱法,十八烷基硅烷键合硅胶为填充剂,乙腈-0.05mol·L-1醋酸钠(1585,pH6.3)为流动相,检测波长为360nm。结果测定胶囊的平均回收率为99.7％(RSD=0.41％,n=5)。结论本实验建立的HPLC可用于测定BSO及其胶囊的含量     

丁胱亚磺酰亚胺对脑胶质细胞瘤GSH作用的研究

目的研究巯基修饰剂了胱亚磺酰亚胺（BSO）对脑胶质细胞瘤GSH含量的修饰作用。方法利用Tietze还原酶法观察BSO对体外培养的脑胶质细胞瘤细胞株及裸小鼠移植瘤模型脑胶质细胞瘤细胞GSH的作用。结果经BSO作用后脑胶质细胞瘤细胞株GSH含量最低为对照4．50％；实体瘤最低为6．74％。结论无论是离体还是整体用药，BSO均能降低脑胶质细胞瘤细胞的GSH含量。     

Role of cytochrome P450-mediated metabolism and identification of novel thiol-conjugated metabolites in mice with phenytoin-induced liver injury

Phenytoin, 5,5-diphenylhydantoin (DPH), is widely used as an anticonvulsant agent. Severe hepatic injury rarely occurs in patients who received DPH. The development of liver injury is thought to be caused by reactive metabolites; however, the metabolites suggested to contribute to hepatotoxicity have not yet been detected in vivo and their effect on developing the liver injury is largely unknown. We recently demonstrated that DPH treatment decreased hepatic glutathione (GSH) contents, and GSH-depleted condition exacerbated DPH-induced liver injury in mice. The aim of the present study was to identify the reactive metabolite and to investigate the role of P450-mediated metabolisms in DPH-induced liver injury. We identified a novel GSH-conjugated (GS)-DPH, a conjugate of putative electrophilic arene oxide intermediate with GSH, in the bile of mice with DPH-induced liver injury. In plasma, cysteine- or N-acetylcysteine-conjugated DPH was detected, and these thiol conjugates levels were correlated with the plasma alanine aminotransferase (ALT) levels. These changes were significantly reduced by pretreatment with P450 inhibitor. Furthermore, the increases of hepatic P450 activities were in parallel with elevation of plasma thiol conjugates levels. These findings suggest that the arene oxide intermediate, which can be converted to thiol conjugates, is involved in DPH-induced liver injury.     

Increased uptake ofl-cysteine andl-cystine by nerve growth factor in rat pheochromocytoma cells

Nerve growth factor is a neurotrophic factor which promotes cell survival and differentiation in the central and peripheral nervous system. The rat pheochromocytoma (PC12) cell has been frequently used to study the actions of nerve growth factor (NGF). Our previous studies demonstrate that pretreatment with NGF for 24 h protects PC12 cells from oxidative stress by increasing glutathione (GSH) concentrations and the activity of γ-glutamylcysteine synthetase, which is a rate-limiting enzyme in GSH synthesis. The synthesis of intracellular GSH is dependent on the availability of the precursor amino acid,l-cysteine. Cells take upl-cystine from the extracellular fluid and convert it tol-Cysteine intracellularly.l-Cysteine is then released from cells to maintain extracellularl-cysteine. Here we report that NGF increased the uptake ofl-cysteine orl-cystine. The increased concentrations ofl-Cysteine orl-cystine by NGF was responsible for the enhanced intracellular GSH concentrations. The increased GSH andl-cysteine concentrations by NGF also served as intracellular antioxidants. The protection of PC12 cells by NGF from oxidative stress was due to the stimulated increased levels of intracellular glutathione andl-cysteine orl-cystine.     

A substantial part of the fallopian tube is left after standard prophylactic bilateral salpingo-oophorectomy

Women with a deleterious germline mutation in BRCA1 or BRCA2 are candidates for bilateral salpingo-oophorectomy (BSO). To address the need for adjustment of the current BSO procedure, we investigated the length and the nature of the fallopian tube epithelium that is not removed by BSO. Fourteen consecutive hysterectomy specimens were collected. Complete cross-sections with a 3-mm interval were made of the tubal lumen from the outside of the uterus at the cutoff point of the current BSO procedure to the uterine cavity and examined for the presence or absence of tubal type (ciliated) epithelium and subepithelial endometrial stroma. The fallopian tube remnant had a median length of 12 mm (range 6-15 mm). Tubal type (ciliated) epithelium was shown to be present in all uteri in the first cross-section containing 100% endometrial stroma, as well as in the uterine cavity of all but two of the hysterectomy specimens. A substantial part of the fallopian tube remains in situ after prophylactic BSO and is covered with tubal type ciliated epithelium. More research is necessary to investigate the role of this remnant part of the tube for BRCA carriers.