Anti-anhedonic effect of selective serotonin reuptake inhibitors with affinity for sigma-1 receptors in picrotoxin-treated mice.

BACKGROUND AND PURPOSE: Prefrontal dopamine release by the combined activation of 5-HT1A and sigma-1 (σ1 ) receptors is enhanced by the GABAA receptor antagonist picrotoxin in mice. Here, we examined whether this neurochemical event was accompanied by behavioural changes. EXPERIMENTAL APPROACH: Male mice were treated with picrotoxin to decrease GABAA receptor function. Their anhedonic behaviour was measured using the female encounter test. The expression of c-Fos was determined immunohistochemically. KEY RESULTS: Picrotoxin caused an anxiogenic effect on three behavioural tests, but it did not affect the immobility time in the forced swim test. Picrotoxin decreased female preference in the female encounter test and attenuated the female encounter-induced increase in c-Fos expression in the nucleus accumbens. Picrotoxin-induced anhedonia was ameliorated by fluvoxamine and S-(+)-fluoxetine, selective serotonin reuptake inhibitors with high affinity for the σ1 receptor. The effect of fluvoxamine was blocked by a 5-HT1A or a σ1 receptor antagonist, and co-administration of the σ1 receptor agonist (+)-SKF-10047 and the 5-HT1A receptor agonist osemozotan mimicked the effect of fluvoxamine. By contrast, desipramine, duloxetine and paroxetine, which have little affinity for the σ1 receptor, did not affect picrotoxin-induced anhedonia. The effect of fluvoxamine was blocked by a dopamine D2/3 receptor antagonist. Methylphenidate, an activator of the prefrontal dopamine system, ameliorated picrotoxin-induced anhedonia. CONCLUSION AND IMPLICATIONS: Picrotoxin-treated mice show anhedonic behaviour that is ameliorated by simultaneous activation of 5-HT1A and σ1 receptors. These findings suggest that the increased prefrontal dopamine release is associated with the anti-anhedonic effect observed in picrotoxin-treated mice.

Efficacy of porcine placental extract on climacteric symptoms in peri- and postmenopausal women.

OBJECTIVES: Injections of human placental extract have long been used to treat menopausal symptoms. Recently, porcine placental extract (PPE), an oral supplement, has been developed for this purpose. The aim of this study was to assess whether PPE has an impact on climacteric symptoms in perimenopausal and postmenopausal women. METHODS: Seventy-six women with climacteric symptoms were enrolled into this open-label, randomized, controlled study. The control group (n = 38) underwent 24 weeks of open treatment with Toki-shakuyaku-san (TJ23), an oral herbal remedy used to alleviate climacteric symptoms. The PPE group (n = 38) received three capsules of PPE/day orally for the initial 12 weeks and six capsules/day for the next 12 weeks. Climacteric symptoms were evaluated in both groups using the Simplified Menopausal Index (SMI) score, Zung's Self-Rating Depression Scale (ZSDS) and the Spielberger State-Trait Anxiety Inventory (STAI) before commencing treatment, after 12 weeks of treatment and on completion of treatment. RESULTS: Treatment with PPE was significantly (p < 0.01) more effective in reducing the SMI, ZSDS and STAI measures at 12 and 24 weeks than TJ23 treatment alone. Treatment with PPE was also significantly effective (p < 0.01) in reducing the subscale scores of the SMI for items such as hot flushes, insomnia, irritability, depression, fatigue and joint pain. PPE treatment had no significant adverse effects. CONCLUSION: Oral PPE treatment is another possible option for treating perimenopausal and postmenopausal women with climacteric symptoms.

Etiology of recurrent acute pancreatitis, with special emphasis on pancreaticobiliary malformation.

PURPOSE: This study was aimed to investigate etiology and clinical profiles of recurrent acute pancreatitis (RAP), particularly from the morphology of the pancreaticobiliary duct system. MATERIAL AND METHODS: Pancreaticobiliary morphology was examined in 230 of 381 patients with acute pancreatitis (AP) using endoscopic retrograde cholangiopancreatography. We analyzed factors associated with RAP including the pancreaticobiliary duct system. RESULTS: RAP was diagnosed in 74 patients (19%). Major etiologies of RAP were alcoholic (38%), idiopathic (26%) and pancreaticobiliary malformation (22%). Patients with alcoholic RAP were significantly younger (47.2±11.6 years) than those with gallstone RAP (67.3±16.8; p<0.05). RAP with pancreaticobiliary malformation (male-to-female ratio: 1:4.3; p<0.01) and gallstone RAP (1:1.7; p<0.05) occurred predominantly in females in comparison with alcoholic RAP (1:0.2). Recurrence rate was 80% for AP with pancreaticobiliary malformation, significantly higher than for the others (p<0.01). Pancreas divisum was suspected as the etiology of mild RAP in 7 patients. Four RAP patients with pancreas divisum underwent endoscopic minor papilla sphincterotomy and improved. Pancreaticobiliary maljunction with biliary dilatation (choledochal cyst) was suspected as the etiology of mild RAP in 3 patients. The 3 RAP patients with choledochal cyst underwent prophylactic flow diversion surgery with complete resection of the dilated common bile duct, and achieved improvement. High confluence of pancreaticobiliary ducts was suspected as the etiology of mild RAP in 6 patients. CONCLUSION: Pancreaticobiliary malformation is one of the major causes of RAP. As some of them benefit from endoscopic or surgical treatment, morphology of the pancreaticobiliary duct system should be examined where possible in RAP patients.

Combination of chronic stress and ovariectomy causes conditioned fear memory deficits and hippocampal cholinergic neuronal loss in mice.

We have recently found that the combination of ovariectomy (OVX) and chronic restraint stress (CS) causes hippocampal pyramidal cell loss and cognitive dysfunction in female rats and that estrogen replacement prevents the OVX/CS-induced morphological and behavioral changes. In this study, to clarify the mechanisms underlying the OVX/CS-mediated memory impairment further, we examined the roles of cholinergic systems in the OVX/CS-induced memory impairment in mice. Female Slc:ICR strain mice were randomly divided into two groups: OVX and sham-operated groups. Two weeks after the operation, the mice of each group were further assigned to CS (6 h/day) or non-stress group. Following the 3-week-stress period, all mice were subjected to contextual fear conditioning, and context- and tone-dependent memory tests were conducted 1 or 24 h after the conditioning. Overburden with 3 weeks of CS from 2 weeks after OVX impaired context- and tone-dependent freezing and the OVX/CS caused significant Nissl-stained neuron-like cell loss in the hippocampal CA3 region, although OVX and CS alone did not cause such behavioral and histological changes. Replacement of 17ß-estradiol for 5 weeks after OVX suppressed OVX/CS-induced memory impairment and hippocampal Nissl-positive cell loss. Furthermore, the OVX/CS mice exhibited a significant decrease in choline acetyltransferase in the hippocampus compared with other groups. The cholinesterase inhibitors donepezil and galantamine ameliorated OVX/CS-induced memory impairment. These data suggest that cholinergic dysfunction may be involved in the OVX/CS-induced conditioned fear memory impairment. Overall, our findings suggest that the OVX/CS mouse model is useful to study the mechanisms underlying estrogen loss-induced memory deficits.

Efficacy of porcine placental extracts with hormone therapy for postmenopausal women with knee pain.

OBJECTIVES: Knee pain related to osteoarthritis increases with age and is more common in middle-aged women. Although hormone replacement therapy (HRT) improves knee pain, women unresponsive to HRT need an effective adjunctive therapy. The aim of this study was to assess whether oral porcine placental extracts (PPE) have an impact on patients with knee pain as an adjunctive therapy combined with HRT. METHODS: Forty-eight postmenopausal women with knee pain receiving HRT were enrolled into this open-label, randomized, controlled study. Subjects were randomized into Group 1 (n= 24) or Group 2 (n=24). Subjects in Group 1 were given 3 months open treatment with calcium (260 mg/day) as adjunctive therapy combined with HRT. Group 2 received PPE (9 capsules/day) as adjunctive therapy combined with HRT. Changes in the degree of knee pain were evaluated by the Visual Analog Scale (VAS). RESULTS: Treatment with PPE was significantly effective in reducing the VAS score for knee pain at 4 weeks (p < 0.05), at 8 weeks (p< 0.01) and at 12 weeks (p<0.01), compared with the control group. Interestingly, the effects continued for 4 weeks after cessation of treatment in the PPE group (p< 0.01) compared with the control group. The PPE treatment had no significant adverse effects on blood biochemical and metabolic profiles, especially related to the risk factors for cardiovascular disease. CONCLUSION: PPE is a possible option as an adjunctive oral supplement in the case of HRT-resistant, long-lasting knee pain.

Role of endogenous pituitary adenylate cyclase-activating polypeptide in adult hippocampal neurogenesis.

Hippocampal neurogenesis occurs throughout life in mammals and has pivotal roles in brain functions. An enriched environment stimulates hippocampal neurogenesis, but the exact mechanisms are still unclear. The present study investigated the role of pituitary adenylate cyclase-activating polypeptide (PACAP) in adult hippocampal neurogenesis under standard or enriched rearing conditions. Rearing in the enriched conditions from 4-weeks old for 4-weeks increased the survival of newly divided cells in the subgranular zone and granule cell layer of the dentate gyrus of wild-type and PACAP-knockout (PACAP-/-) mice. The increase in the survival in the granule cell layer was less in PACAP-/- mice than in the wild-type mice. In contrast, the proliferation of newly divided cells in mice reared in the standard and enriched conditions did not differ between the wild-type and PACAP-/- mice. Regarding the differentiation of newborn cells in the dentate gyrus, most of the newly divided cells exhibited the neuronal phenotype in both the wild-type and PACAP-/- mice under standard and enriched conditions. These findings suggest that endogenous PACAP is partly involved in the survival of the enriched environment-induced generation, but not in the basal rate, of newborn cells in the dentate gyrus of the adult hippocampus.

Involvement of decreased muscarinic receptor function in prepulse inhibition deficits in mice reared in social isolation.

BACKGROUND AND PURPOSE: We have previously reported that galantamine, a weak acetylcholinesterase inhibitor, improves prepulse inhibition (PPI) deficits in mice reared in social isolation. ACh receptors are involved in the underlying mechanism of PPI, but whether rearing in social isolation causes dysfunction of the cholinergic system is unknown. In this study, we examined the involvement of muscarinic receptors in the improvement of PPI deficits induced by galantamine, and whether the cholinergic system is altered in mice reared in isolation. EXPERIMENTAL APPROACH: Three-week-old male ddY mice were housed in isolated cages for 6 weeks before the initiation of experiments to create PPI deficits. Cholinergic functions were determined by measuring the behavioural and neurochemical responses to nicotinic and muscarinic receptor agonists. KEY RESULTS: The improvement by galantamine of social isolation-induced PPI deficits was blocked by scopolamine, a non-selective muscarinic antagonist, and telenzepine, a preferential M1 receptor antagonist. Activation of M1 receptors improved social isolation-induced PPI deficits. Social isolation did not affect choline acetyltransferase and acetylcholinesterase activities in the prefrontal cortex and hippocampus, but it reduced the locomotor-suppressive response to muscarinic agonist oxotremorine, but not to nicotine. The isolation also attenuated the M1 receptor agonist N-desmethylclozapine-induced increase in prefrontal dopamine release. CONCLUSIONS AND IMPLICATIONS: Galantamine improves PPI deficits of mice reared in social isolation via activation of M1 receptors. Social isolation reduces the muscarinic, especially M1, receptor function and this is involved in PPI deficits.

Galantamine improves apomorphine-induced deficits in prepulse inhibition via muscarinic ACh receptors in mice.

BACKGROUND AND PURPOSE: Galantamine, a weak acetylcholine esterase (AChE) inhibitor and allosteric potentiator of nicotinic ACh receptors (nAChRs), improves apomorphine-induced deficits in prepulse inhibition (PPI), sensory information-processing deficits, via a nAChR-independent mechanism. The present study examined the role of muscarinic ACh receptors (mAChRs) in the effect of galantamine, and studied the mechanism of galantamine-induced increases in prefrontal ACh levels in mice. EXPERIMENTAL APPROACH: Apomorphine (1 mg kg(-1)) was administered to male ddY mice (9-10 weeks old) to create a PPI deficit model. Extracellular ACh concentrations in the prefrontal cortex were measured by in vivo microdialysis. KEY RESULTS: Galantamine- and donepezil-mediated improvements in apomorphine-induced PPI deficits were blocked by the preferential M(1) mAChR antagonist telenzepine. The mAChR agonist oxotremorine also improved apomorphine-induced PPI deficits. Galantamine, like donepezil, increased extracellular ACh concentrations in the prefrontal cortex. Galantamine-induced increases in prefrontal ACh levels were partially blocked by the dopamine D(1) receptor antagonist SCH23390, but not by antagonists of mAChRs (telenzepine) and nAChRs (mecamylamine). Galantamine increased dopamine, but not 5-HT, release in the prefrontal cortex. CONCLUSIONS AND IMPLICATIONS: Galantamine improves apomorphine-induced PPI deficits by stimulating mAChRs through increasing brain ACh levels via a dopamine D(1) receptor-dependent mechanism and AChE inhibition.

[Esophago-bronchial fistula confirmed with bronchoscopy utilized an indocyanine green].

The patient was a 54-year-old female with both headache and vomit presented to the emergency room. Endoscopic examination revealed an advanced esophageal cancer located on the middle thoracic esophagus. Histological analysis revealed squamous cell carcinoma. The clinical stage was diagnosed as T4N2M0 and this case was treated by the chemoradiation. She presented progressive moist cough after chemoradiotherapy. Esophagography demonstrated esophago-bronchial fistula (EBF). EBF was not detected by routine broncoscopy. To confirm fistula, we were performed the bronchoscopy which utilized an indocyanine green. Contrast media colored green were over from the superior segmental bronchus in a bronchoscope. The bronchoscope which utilized an indocyanine green is effective for EBF.

Ginkgo biloba extract EGb 761 attenuates hippocampal neuronal loss and cognitive dysfunction resulting from chronic restraint stress in ovariectomized rats.

We have recently found that a combination of ovariectomy (OVX) and chronic restraint stress causes cognitive dysfunction and reduces hippocampal CA3 neurons in female rats and that estrogen replacement suppresses the OVX/stress-induced behavioral and morphological changes. In this study, we examined the effect of Ginkgo biloba extract (EGb 761), a popular herbal supplement, on the cognitive dysfunction and neuromorphological change in OVX/stress-subjected rats. Female Fisher 344 rats were randomly divided into three groups: vehicle-treated OVX, EGb 761 (50 mg/kg) -treated OVX and vehicle-treated sham-operated control groups. Two months after ovariectomy, all animals received restraint stress for 21 days (6 h/day), and were then subjected to a novel object recognition test followed by morphological examination by Nissl staining. EGb 761 was orally administered once daily until the behavioral analysis was done. Treatment with EGb 761 improved memory impairment and neuronal loss of hippocampus in the OVX/stress-subjected group in the same ways as 17beta-estradiol. On the other hand, EGb 761 did not affect the loss of bone mineral density and increase in body weight after OVX, although 17beta-estradiol attenuated them. These results have important implications for neuroprotective and cognition enhancing effects of EGb 761 in postmenopausal women and suggest that the effects are mediated by a different mechanism from estrogen.

17beta-estradiol attenuates hippocampal neuronal loss and cognitive dysfunction induced by chronic restraint stress in ovariectomized rats.

Several lines of evidence suggest that hormonal changes after menopause may play an important role in the incidence of cognitive dysfunction, and also in the development of Alzheimer's disease. In this study, we investigated the effect of estrogen on cognitive function in rats under different stress environment. Female rats were divided into four groups: two groups were ovariectomized (OVX) and two were sham-operated. One group each of OVX and sham rats was kept in a normal environment, and the other groups were assigned to a daily restraint stress (6 h/day) for 21 days from 2 months after the operation. Following the stress period, subjects were tested for performance in novel object recognition test and then used for morphological and neurochemical analyses. The OVX plus stress (OVX/stress) group showed a significant impairment of recognition of novel objects, compared with the other groups. The OVX/stress group also showed a marked decrease in the number of pyramidal cells of the CA3 region and levels of brain-derived neurotrophic factor mRNA in the hippocampus. We further examined the effect of estrogen against cognitive dysfunction and hippocampal changes of OVX/stress rats. Vehicle or 17beta-estradiol (E2) at 20 microg/day was s.c. administered to OVX/stress rats from 2 days before the stress period to the end of behavioral analysis through an implantable osmotic pump. Chronic E2 treatment decreased stress response and improved the cognitive and morphological impairments relative to vehicle group. These data have important implications for cognition enhancing effect of estrogen treatment in postmenopausal women.

Anti-apoptotic effect of cGMP in cultured astrocytes: inhibition by cGMP-dependent protein kinase of mitochondrial permeable transition pore.

Reperfusion of cultured astrocytes with normal medium after exposure to H(2)O(2)-containing medium causes apoptosis. We have recently shown that ibudilast, which has been used for bronchial asthma and cerebrovascular disorders, attenuated the H(2)O(2)-induced apoptosis of astrocytes via the cGMP signaling pathway. This study examines the mechanism underlying the protective effect of cGMP. The membrane-permeable cGMP analog dibutyryl-cGMP attenuated the H(2)O(2)-induced decrease in cell viability, DNA ladder formation, nuclear condensation, reduction of the mitochondrial membrane potential, cytochrome c release from mitochondria, and caspase-3 activation in cultured astrocytes. These effects of dibutyryl-cGMP were almost completely inhibited by the cGMP-dependent protein kinase (PKG) inhibitor KT5823. In isolated rat brain mitochondria, cGMP in the presence of cytosolic extract from astrocytes inhibited the mitochondrial permeability transition pore (PTP) as determined by monitoring Ca(2+)-induced mitochondrial swelling. This ability of the cytosolic extract was inactivated by heat treatment and was mimicked by exogenous PKG. The effect of cGMP on the mitochondrial swelling was blocked by KT5823. The PTP inhibitors cyclosporin A and bongkrekic acid prevented the H(2)O(2)-induced decrease in cell viability and caspase-3 activation. These findings demonstrate that cGMP inhibits the mitochondrial PTP via the activation of PKG, and the prevention of mitochondrial dysfunction contributes to its anti-apoptotic effect.

Phosphorylation of histones triggers DNA fragmentation in thymocyte undergoing apoptosis induced by protein phosphatase inhibitors.

The treatment of thymocytes with protein phosphatase inhibitors such as calyculin A and okadaic acid resulted in apoptosis with a concomitant increase in phosphorylation of nuclear proteins. The phosphorylated protein in the thymocyte nuclei induced by protein phosphatase inhibitors was identified as histones by the use of two-dimensional polyacrylamide gel electrophoresis. These compounds accelerated the phosphorylation of histone H2A, H3, and H1. On the other hand, little phosphorylation of H2B and H4 by these compounds was observed. The effect of these compounds on the level of nuclear histones was also examined using high-performance capillary electrophoresis. No significant changes in the level of histones were seen in the nuclei of thymocytes treated with calyculin A and okadaic acid. Thus, the induction of thymocyte apoptosis is involved in the chemical modification of histones but not the change in their quantity. Moreover, the treatment of thymocytes with calyculin A increased the sensitivity toward endogenous DNase in the nuclei. These results suggest that phosphorylation of histones, especially H2A, H3, and H1, is an early step of triggering DNA fragmentation in thymocyte apoptosis.

[Delayed apoptosis and its regulation in astrocytes].

Astrocytes, the most abundant glial cell type in the brain, are considered to have physiological and pathological roles in neuronal activities. We found that reperfusion of cultured astrocytes after Ca2+ depletion causes Ca2+ overload followed by delayed cell death and the Na(+)-Ca2+ exchanger in the reverse mode is responsible for this Ca(2+)-mediated cell injury (Ca2+ paradox injury). The Ca2+ paradox injury of cultured astrocytes is considered to be an in vitro model of ischemia/reperfusion injury, since a similar paradoxical change in extracellular Ca2+ concentration is reported in ischemic brain tissue. This review summarizes the mechanisms underlying the Ca(2+)-mediated injury of astrocytes and the protective effects of drugs against Ca2+ reperfusion injury. This study shows that Ca2+ reperfusion injury of astrocytes is accompanied by apoptosis as evidenced by DNA fragmentation and nuclear condensation. Calpain, reactive oxygen species, calcineurin, caspase-3, and NF-kappa B are involved in Ca2+ reperfusion-induced delayed apoptosis of astrocytes. Several drugs including CV-2619, T-588 and ibudilast protect astrocytes against the delayed apoptosis. CV-2619 prevents astrocytes from the delayed apoptosis by production of nerve growth factor, resulting in an activation of mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) and phosphatidylinositol-3 (PI3) kinase signal pathways. The protective effect of T-588 is mainly mediated by an activation of MAP/ERK signal cascade. Moreover, ibudilast prevents the Ca2+ reperfusion-induced delayed apoptosis of astrocytes via cyclic GMP signaling pathway. Further studies in this system will contribute to the development of new drugs that attenuate ischemia/reperfusion injury via modulation of astrocytes.

Ibudilast attenuates astrocyte apoptosis via cyclic GMP signalling pathway in an in vitro reperfusion model.

We examined the effect of 3-isobutyryl-2-isopropylpyrazolo[1,5-a]pyridine (ibudilast), which has been clinically used for bronchial asthma and cerebrovascular disorders, on cell viability induced in a model of reperfusion injury. Ibudilast at 10 - 100 microM significantly attenuated the H(2)O(2)-induced decrease in cell viability. Ibudilast inhibited the H(2)O(2)-induced cytochrome c release, caspase-3 activation, DNA ladder formation and nuclear condensation, suggesting its anti-apoptotic effect. Phosphodiesterase inhibitors such as theophylline, pentoxyfylline, vinpocetine, dipyridamole and zaprinast, which increased the guanosine-3',5'-cyclic monophosphate (cyclic GMP) level, and dibutyryl cyclic GMP attenuated the H(2)O(2)-induced injury in astrocytes. Ibudilast increased the cyclic GMP level in astrocytes. The cyclic GMP-dependent protein kinase inhibitor KT5823 blocked the protective effects of ibudilast and dipyridamole on the H(2)O(2)-induced decrease in cell viability, while the cyclic AMP-dependent protein kinase inhibitor KT5720, the cyclic AMP antagonist Rp-cyclic AMPS, the mitogen-activated protein/extracellular signal-regulated kinase inhibitor PD98059 and the leukotriene D(4) antagonist LY 171883 did not. KT5823 also blocked the effect of ibudilast on the H(2)O(2)-induced cytochrome c release and caspase-3-like protease activation. These findings suggest that ibudilast prevents the H(2)O(2)-induced delayed apoptosis of astrocytes via a cyclic GMP, but not cyclic AMP, signalling pathway.

SEA0400, a novel and selective inhibitor of the Na+-Ca2+ exchanger, attenuates reperfusion injury in the in vitro and in vivo cerebral ischemic models.

The effect of the newly synthesized compound 2-[4-[(2,5-difluorophenyl)methoxy]phenoxy]-5-ethoxyaniline (SEA0400) on the Na+-Ca2+ exchanger (NCX) was investigated and compared against that of 2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea (KB-R7943). In addition, the effects of SEA0400 on reperfusion injury in vitro and in vivo were examined. SEA0400 was extremely more potent than KB-R7943 in inhibiting Na+-dependent Ca2+ uptake in cultured neurons, astrocytes, and microglia: IC50s of SEA0400 and KB-R7943 were 5 to 33 nM and 2 to 4 microM, respectively. SEA0400 at the concentration range that inhibited NCX exhibited negligible affinities for the Ca2+ channels, Na+ channels, K+ channels, norepinephrine transporter, and 14 receptors, and did not affect the activities of the Na+/H+ exchanger, Na+,K+-ATPase, Ca2+-ATPase, and five enzymes. SEA0400, unlike KB-R7943, did not inhibit the store-operated Ca2+ entry in cultured astrocytes. SEA0400 attenuated dose- dependently paradoxical Ca2+ challenge-induced production of reactive oxygen species, DNA ladder formation, and nuclear condensation in cultured astrocytes, whereas it did not affect thapsigargin-induced cell injury. Furthermore, administration of SEA0400 reduced infarct volumes after a transient middle cerebral artery occlusion in rat cerebral cortex and striatum. These results indicate that SEA0400 is the most potent and selective inhibitor of NCX, and suggest that the compound may exert protective effects on postischemic brain damage.

CV-2619 protects cultured astrocytes against reperfusion injury via nerve growth factor production.

In this study, we examined the effect of the neuroprotective agent 2, 3-dimethoxy-5-methyl-6-(10-hydroxydecyl)-1,4-benzoquinone (CV-2619) on reperfusion injury in cultured rat astrocytes after exposure to hydrogen peroxide (H(2)O(2))-containing medium. CV-2619 (10 nM to 10 microM) significantly attenuated the reperfusion-induced decrease in cell viability. The compound showed an anti-apoptotic effect in this astrocyte injury model. Antioxidants such as ascorbic acid, alpha-tocopherol and reduced glutathione also inhibited H(2)O(2) exposure-induced cytotoxicity. CV-2619 did not affect the levels of reactive oxygen species, but it increased nerve growth factor (NGF) production. The effect of CV-2619 on H(2)O(2) exposure-induced cytotoxicity was blocked by cycloheximide and anti-NGF antibody. The protective effect of CV-2619 was antagonized by the mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase inhibitor 2'-amino-3'-methoxyflavone and the phosphatidylinositol-3 kinase inhibitor wortmannin. These findings suggest that the effect of CV-2619 is mediated at least partly by NGF production in astrocytes and that ERK and phosphatidylinositol-3 kinases play a role in the downstream mechanism.

T-588 inhibits astrocyte apoptosis via mitogen-activated protein kinase signal pathway.

The effect of (1R)-1-benzo[b]thiophen-5-yl-2-[2-(diethylamino)ethoxy]ethan -1-ol hydrochloride (T-588), a cognition enhancer, on reperfusion injury was studied in cultured rat astrocytes. T-588 at 1-10 microM partially protected astrocytes against reperfusion injury after exposure to Ca(2+)-free medium or hydrogen peroxide. Nerve growth factor (NGF) had a similar protective effect. Addition of both T-588 and NGF resulted in complete protection against Ca(2+) reperfusion injury. T-588 did not stimulate NGF production in astrocytes. The effect of T-588 on Ca(2+) reperfusion injury including apoptosis was inhibited by the mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase inhibitor 2'-amino-3'-methoxyflavone (PD98059), but not by the phosphoinositide 3-kinase inhibitor wortmannin. The effect of NGF was inhibited by PD98059 and wortmannin. T-588 stimulated rapidly the phosphorylation of ERK, but did not affect that of Akt in astrocytes. These findings suggest that the ERK MAP kinase pathway has a role in the protective effects of T-588 and NGF.

Apoptosis in Ca2 + reperfusion injury of cultured astrocytes: roles of reactive oxygen species and NF-kappaB activation.

We previously reported that incubation of cultured astrocytes in Ca2 + -containing medium after exposure to Ca2 + -free medium caused Ca2 + influx followed by delayed cell death. Here, we studied the mechanisms underlying the Ca2 + -mediated injury of cultured astrocytes. Our results show that Ca2 + reperfusion injury of astrocytes appears to be mediated by apoptosis, as demonstrated by DNA fragmentation and prevention of death by caspase-3 inhibitors. Paradoxical Ca2 + challenge stimulated rapidly reactive oxygen species (ROS) production. Ca2 + reperfusion injury of astrocytes was influenced by several reagents which modified ROS production. When astrocytes were exposed to hydrogen peroxide (H2O2) for 30 min and then incubated without H2O2 for 1-5 days, cell toxicity including apoptosis was observed. Ca2 + reperfusion injury induced by Ca2 + depletion or H2O2 exposure was blocked by the iron chelator 1, 10-phenanthroline, the NF-kappaB inhibitor pyrrolidinedithiocarbamate and the calcineurin inhibitor FK506. Incubation in normal medium after H2O2 exposure rapidly increased the level of nuclear NF-kappaB p65 subunit, and the effect was blocked by 1,10-phenanthroline, pyrrolidinedithiocarbamate and FK506. These findings indicate that Ca2 + reperfusion-induced apoptosis is mediated at least partly by ROS production and ROS cause NF-kappaB activation in cultured astrocytes.