Transcriptional Remodeling in Primary Hippocampal Astrocytes from an Alzheimer's Disease Mouse Model.

BACKGROUND: It is well known that alterations in astrocytes occur in Alzheimer's disease and reactive astrogliosis is one of the hallmarks of the disease. Recently, data has emerged that suggests that alterations in astrocytes may also occur early in the pathogenesis of the disease. OBJECTIVE: The aim of present work was to characterize the transcriptional alterations occurring in cultured astrocytes from 3xTg-AD mouse pups compared to control non-transgenic mice. Furthermore, we also compared these changes to those reported by others in astrocytes from symptomatic AD mice. METHOD: We conducted a whole-genome microarray study on primary cultured astrocytes from the hippocampus of 3xTg-AD and non-transgenic mouse newborn pups. We used cross-platform normalization and an unsupervised hierarchical clustering algorithm to compare our results with other datasets of cultured or freshly isolated astrocytes, including those isolated from plaque-stage APPswe/PS1dE9 AD mice. RESULTS: We found a set of 993 genes differentially expressed in 3xTg-AD as compared with non-Tg astrocytes. Over-represented gene ontology terms were related to calcium, cell-cell communication, mitochondria, transcription, nucleotide binding and phosphorylation. Of note, no genes related to inflammation were found in cultured 3xTg-AD astrocytes. Comparison with astrocytes isolated from plaque stage APPswe/PS1dE9 showed that 882 out of 993 genes were selectively changed in primary 3xTg-AD astrocytes while 50 genes were co-regulated and 61 were anti-regulated (regulated in the opposite direction in the datasets). CONCLUSION: Our data show that in cultured astrocytes from an AD mouse model, transcriptional changes occur and are different from those reported in models mimicking later stages of the disease.

Common European Mitochondrial Haplogroups in the Risk for Radiation-induced Subcutaneous Fibrosis in Breast Cancer Patients.

AIMS: The contribution of mitochondrial DNA (mtDNA) variations to clinical radiosensitivity is largely unknown. In the present study, we evaluated the association between mtDNA haplogroups and the risk of radiation-induced subcutaneous fibrosis after postoperative radiotherapy in breast cancer patients. MATERIALS AND METHODS: Subcutaneous fibrosis was scored according to the Late Effects of Normal Tissue-Subjective Objective Management Analytical (LENT-SOMA) scale in 286 Italian breast cancer patients who received radiotherapy after breast-conserving surgery. Eight mtDNA single nucleotide polymorphisms that define the nine major haplogroups in the European population were determined by polymerase chain reaction restriction fragment length polymorphism analysis on genomic DNA extracted from peripheral blood. RESULTS: In a Kaplan-Meier analysis evaluated by the Log-rank test, carriers of haplogroup H were found to be at lower risk of grade ≥2 subcutaneous fibrosis (P = 0.018) compared with all other haplotypes combined. In the multivariate Cox regression analysis adjusted for clinical factors (body mass index, breast diameter, adjuvant treatment, dose per fraction, radiation type and acute skin toxicity), haplogroup H emerged as a protective factor for moderate to severe radiation-induced fibrosis at a nominal significance level (hazard ratio: 0.50, 95% confidence interval 0.27-0.92, P = 0.027), which did not survive correction for multiple testing. CONCLUSIONS: Our results suggest a protective effect of the mitochondrial haplogroup H in the development of radiation-induced fibrosis in breast cancer patients. However, the loss of statistical significance after correction for multiple comparisons and the lack of an independent validation cohort make our findings preliminary, requiring further confirmation in large-scale prospective studies.

Human recombinant follicle stimulating hormone (rFSH) compared to urinary human menopausal gonadotropin (HMG) for ovarian stimulation in assisted reproduction: a literature review and cost evaluation.

BACKGROUND: Gonadotropins are protein hormones which are central to the complex endocrine system that regulates normal growth, sexual development, and reproductive function. There is still a lively debate on which type of gonadotropin medication should be used, either human menopausal gonadotropin or recombinant follicle-stimulating hormone. The objective of the study was to perform a systematic review of the recent literature to compare recombinant follicle-stimulating hormone to human menopausal gonadotropin with the aim to assess any differences in terms of efficacy and to provide a cost evaluation based on findings of this systematic review. METHODS: The review was conducted selecting prospective, randomized, controlled trials comparing the two gonadotropin medications from a literature search of several databases. The outcome measure used to evaluate efficacy was the number of oocytes retrieved per cycle. In addition, a cost evaluation was performed based on retrieved efficacy data. RESULTS: The number of oocytes retrieved appeared to be higher for human menopausal gonadotropin in only 2 studies while 10 out of 13 studies showed a higher mean number of oocytes retrieved per cycle for recombinant follicle-stimulating hormone. The results of the cost evaluation provided a similar cost per oocyte for both hormones. CONCLUSIONS: Recombinant follicle-stimulating hormone treatment resulted in a higher oocytes yield per cycle than human menopausal gonadotropin at similar cost per oocyte.

Functional polymorphisms in COMT and SLC6A4 genes influence the prognosis of patients with medication overuse headache after withdrawal therapy.

BACKGROUND AND PURPOSE: It is currently unknown if common genetic variants influence the prognosis of patients with medication overuse headache (MOH). Here the role of two common single nucleotide polymorphisms in the COMT gene (rs4680 and rs6269), as well as the STin2 variable number tandem repeat (VNTR) polymorphism in the SLC6A4 gene, were evaluated as predictors for long-term outcomes of MOH patients after withdrawal therapy. METHODS: Genotyping was conducted by polymerase chain reaction (PCR), PCR restriction fragment length polymorphism analysis or real-time PCR allelic discrimination assay on genomic DNA extracted from peripheral blood. Gene variants association was evaluated by logistic regression analysis adjusted for clinical confounding factors, and the threshold of statistical significance for multiple testing was set at P < 0.012. RESULTS: Sixty-five MOH patients with unsuccessful detoxification and 83 MOH patients with effective drug withdrawal therapy were available for the analysis. rs4680G allele carriers or the COMT rs6269G-rs4680G haplotype were found to be associated with a lower risk of relapse within the first year after successful detoxification therapy, in comparison with homozygous rs4680A allele carriers [odds ratio (OR) 0.17, 95% confidence interval (CI) 0.05-0.61, P = 0.007] or with the COMT rs6269A-rs4680A haplotype (OR 0.19, 95% CI 0.06-0.54, P = 0.003), respectively. In addition, carriers of the STin2 VNTR short allele were found at higher odds for the composite poor outcome including unsuccessful withdrawal therapy and relapse within 12 months of follow-up after successful detoxification (OR 2.81, 95%CI 1.26-6.25, P = 0.009). CONCLUSIONS: Our results indicate that genotyping for COMT rs4680 and SLC6A4 STin2 VNTR could be useful for the identification of MOH patients at higher risk of poor prognosis after drug withdrawal.

Association of haplotype combination of serotonin transporter gene polymorphisms with monthly headache days in MOH patients.

OBJECTIVES: To evaluate the role of 5-HTTLPR, STin2 VNTR, and rs1042173T>G polymorphisms of the serotonin transporter gene (SLC6A4) as susceptibility factors for medication overuse headache (MOH) and to assess their value as predictors of the number of headache days per month, a potential marker of disease severity. METHODS: Genotyping was performed by PCR and PCR-RFLP on genomic DNA extracted from peripheral blood of 227 MOH patients and 312 control subjects. Logistic regression analysis was used to evaluate the association between the SL6A4 gene polymorphisms and MOH risk. The association between polymorphic variants and monthly headache days was evaluated by linear regression analysis. RESULTS: Logistic regression analysis, adjusted for age and gender, revealed a nominal association between rs1042173T>G and MOH risk (TT vs. TG + GG, OR: 1.58 95% CI: 1.05-2.37, P = 0.028). In the linear regression analysis adjusted for age, gender, primary headache diagnosis, acute drug overused and monthly drug number, STin2 VNTR was found nominally associated with monthly headache days (12/12 vs. others, difference: 1.55 days, 95% CI: 0.01-3.08, P = 0.050). When STin2 VNTR and rs1042173T>G were analyzed in haplotypic combination, a global haplotype association emerged with monthly headache days which remained significant after Bonferroni correction for multiple comparisons (global haplotype association P = 0.0056). CONCLUSION: Although a minor contribution of SLC6A4 variants in the genetic liability of MOH cannot be excluded, haplotype-based analysis of STin2 VNTR and rs1042173T>G polymorphisms allowed to identify a subgroup of MOH patients with a higher number of monthly headache and, possibly, with a more severe disease.

Gene regulation in the frontal cortex of rats exposed to the chronic mild stress paradigm, an animal model of human depression.

In the present study, we have coupled the chronic mild stress (CMS) protocol with Affymetrix microarray technology to screen the rat genome for gene changes in the frontal cortex. The aim of our work was to assess whether the CMS protocol could be a useful experimental model to provide insights into the molecular basis of depression. Under our experimental conditions, 59 transcripts changed by more than +/-1.5-fold between naïve and anhedonic rats and showed significantly altered expression levels (P < 0.05). Among these, 18 were upregulated (fold change range +1.509 to +3.161) and 41 were downregulated (fold change range -1.505 to -2.659). To confirm the data obtained with microarrays, we used real-time reverse transcription polymerase chain reaction (RT-PCR). The results confirmed the downregulation of Itga6, Camk2a, Plcb1, Cart, Gad1, Homer1 and Th and the upregulation of Egr2 and Ptgs2 observed in the DNA microarray analysis. Moreover, the fold change data of the nine validated transcripts from microarray analysis and real-time polymerase chain reaction showed a good correlation (r = 0.863, 7 d.f., P < 0.01; slope = 0.976). It is of great interest that prostaglandin-endoperoxide synthase 2, tyrosine hydroxylase, Cart, Homer1 and glutamate decarboxylase have already been implicated in affective disorders by different approaches in previous reports. In conclusion, our findings indicate that the CMS paradigm is a useful preclinical model with which to investigate the molecular basis of anhedonia and to help in the discovery of novel targets for antidepressant drugs.

Inhibitors of histone deacetylase (HDAC) restore the p53 pathway in neuroblastoma cells.

BACKGROUND AND PURPOSE: Inhibitors of histone deacetylase (HDAC) are emerging as a promising class of anti-cancer drugs, but a generic deregulation of transcription in neoplastic cells cannot fully explain their therapeutic effects. In this study we evaluated alternative molecular mechanisms by which HDAC inhibitors could affect neuroblastoma viability. EXPERIMENTAL APPROACH: Effects of HDAC inhibitors on survival of the I-type SK-N-BE and the N-type NB SH-SY5Y neuroblastoma cell lines were assessed by the MTT assay. Molecular pathways leading to this were examined by western blot, confocal microscopy and cytofluorometry. The mRNA levels of apoptotic mediators were assessed semi-quantitatively by RT-PCR. Tumour-suppressor p53 trans activity was assessed in EMSA experiments. HDAC inhibitors were also studied in cells subjected to plasmid-based p53 interference (p53i). KEY RESULTS: HDAC inhibitors induced cell death via the mitochondrial pathway of apoptosis with recruitment of Bcl-2 family members. Bcl-2 overexpression rendered neuroblastoma cells resistant to HDAC inhibitor treatment. Low concentrations of HDAC inhibitors (0.9 mM) caused a G(2) cell-cycle arrest and a marked upregulation of the p21/Waf1/Cip1 protein. HDAC inhibitors also activate the p53 protein via hyper-acetylation and nuclear re-localization, without affecting its protein expression. Accordingly, HDAC inhibitor-induced cell-killing and p21/Waf1/Cip1 upregulation is impaired in p53i-cells. CONCLUSIONS AND IMPLICATIONS: In neuroblastoma cells, HDAC inhibitors may overcome the resistance to classical chemotherapeutic drugs by restoring the p53 tumour-repressor function via its hyper-acetylation and nuclear migration, events usually impaired in such tumours. In neuroblastoma cells, HDAC inhibitors are not able to induce p21/Waf1/Cip1 in the absence of a functional p53.

Calcineurin primes immature gonadotropin-releasing hormone-secreting neuroendocrine cells for migration.

During development, many neurons display calcium-dependent migration, but the role of this messenger in regulating gene expression leading to this event has not yet been elucidated. Among the decoders of calcium signals is calcineurin, a Ca(2+)/calmodulin serine/threonine phosphatase that has been involved in both short-term and long-term cellular changes. By using immortalized GnRH-secreting neurons, we now show that, in vitro, Ca(2+)-dependent gene expression, proceeding via calcineurin and the transcription factor nuclear factor of activated T cells, is a key player controlling the chemomigratory potential of developing GnRH-secreting neurons. Furthermore, our data highlight the switch nature of this phosphatase, whose activation or inactivation guides cells to proceed from one genetic program to the next.

Sphingosine releases Ca2+ from intracellular stores via the ryanodine receptor in sea urchin egg homogenates.

Various reports have demonstrated that the sphingolipids sphingosine and sphingosine-1-phosphate are able to induce Ca2+ release from intracellular stores in a similar way to second messengers. Here, we have used the sea urchin egg homogenate, a model system for the study of intracellular Ca2+ release mechanisms, to investigate the effect of these sphingolipids. While ceramide and sphingosine-1-phosphate did not display the ability to release Ca2+, sphingosine stimulated transient Ca2+ release from thapsigargin-sensitive intracellular stores. This release was inhibited by ryanodine receptor blockers (high concentrations of ryanodine, Mg2+, and procaine) but not by pre-treatment of homogenates with cADPR, 8-bromo-cADPR or blockers of other intracellular Ca2+ channels. However, sphingosine rendered the ryanodine receptor refractory to cADPR. We propose that, in the sea urchin egg, sphingosine is able to activate the ryanodine receptor via a mechanism distinct from that used by cADPR.

Novel neuronal targets for the acetylcholinesterase inhibitor donepezil.

The effects of the acetylcholinesterase inhibitor donepezil on cell viability and proliferation events have been analysed in SH-SY5Y human neuroblastoma cells. Short- (48 h) or long-term (7 days) exposure of SH-SY5Y cells to donepezil (100 nM-10 microM) induced a concentration-dependent inhibition of cell proliferation that was not modified by muscarinic and nicotinic receptor antagonists, or mimicked by galantamine, and was not related to induction of apoptosis. By analysing the distribution profile of cell populations within the cell cycle following treatment with 10 microM donepezil, a reduction of cells in the S-G2/M phases of the cycle and a parallel increase of the G0/G1 population were observed. In addition, the expression of two cyclins of the G1/S and G2/M transitions, cyclin E and cyclin B, was significantly reduced in donepezil-treated cells. In contrast, the expression of the cell cycle inhibitor p21 rapidly (6 h) increased following exposure to the drug. Finally, donepezil increased the expression of the neuronal marker MAP-2 in selected subpopulations of SH-SY5Y cells, suggesting that the effect on cell proliferation by donepezil may correlate to a trend to neuronal differentiation.

Glia mediates the neuroprotective action of estradiol on beta-amyloid-induced neuronal death.

17beta-Estradiol (17beta-E(2)) is known to exert neuroprotective activity against beta-amyloid, but its exact target and mechanism of action in this effect have not been elucidated. The involvement of astroglia in neuroprotection of 17beta-E(2) against the beta-amyloid fragment [betaAP((25-35))] has been evaluated using an experimental paradigm in which medium conditioned from rat astroglia pretreated with 17beta-E2 was transferred to pure rat cortical neurons challenged with 25 microm betaAP((25-35)) for 24 h. The toxicity of betaAP((25-35)) was assessed by flow cytometry, evaluating the ability of the peptide to induce an aberrant mitotic cell cycle in neurons. The results obtained indicate that conditioned medium from astrocytes preexposed to 17beta-E(2) for 4 h increased the viability of cortical neurons treated with betaAP((25-35)). This effect was not modified by treatment with the estrogen receptor antagonist ICI 182,780, added directly to neurons, nor was it mimicked by direct addition of 17beta-E(2) to neuronal cultures during exposure to betaAP((25-35)). A soluble factor stimulated by 17beta-E(2) seemed to be involved, and accordingly, the intracellular and released levels of TGF-beta1 were increased by 17beta-E(2) treatment, as established by Western blot analysis. In addition, the intracellular content of TGF-beta1 in immunopositive cells, as detected by flow cytometry, was reduced, suggesting that 17beta-E(2) stimulated mainly the release of the cytokine. In support of a role for TGF-beta1 in astrocyte-mediated 17beta-E(2) neuroprotective activity, incubation with a neutralizing anti-TGF-beta1 antibody significantly modified the reduction of neuronal death induced by 17beta-E(2)-treated astrocyte-conditioned medium.

A novel mechanism for pergolide-induced neuroprotection: inhibition of NF-kappaB nuclear translocation.

We previously demonstrated that the dopaminergic agonist pergolide, independently from its DA agonist activity, can exert neuroprotective effects against cell death induced in SH-SY5Y neural cells by H(2)O(2) treatment. Since oxidative stress in SH-SY5Y neural cells is known to activate the NF-kappaB pathway we tested the hypothesis that pergolide may interfere with NF-kappaB activity. Based on Western blot analysis and immunocytochemistry, pergolide was found to prevent H(2)O(2)-induced apoptosis by inhibiting NF-kappaB nuclear translocation and activation of p53 signalling pathway. Similarly, the cell-permeable SN50 peptide, which is known to block NF-kappaB nuclear translocation, prevented both H(2)O(2)-induced p53 expression and apoptosis. The mechanism of action of pergolide responsible for neuroprotection differed from that of antioxidants. In fact, Vitamin E, contrary to pergolide and SN50, rescued neuronal cells from H(2)O(2)-induced apoptosis acting upstream NF-kappaB activation, as demonstrated by the prevention of H(2)O(2)-induced IkappaB degradation. These data suggest a novel site of action of pergolide that may account for additional pharmacological properties of this drug.

Characterization of ionotropic glutamate receptors in human lymphocytes.

The effect of L-glutamate (Glu) on human lymphocyte function was studied by measuring anti-CD(3) monoclonal antibody (mAb) or phytohaemagglutinin (PHA)-induced intracellular Ca(2+) ([Ca(2+)](i)) rise (Fura-2 method), and cell proliferation (MTT assay). Glu (0.001 - 100 microM) did not modify basal lymphocyte [Ca(2+)](i), but significantly potentiated the effects of anti-CD(3) mAb or PHA. Maximal [Ca(2+)](i) rises over resting cells were: 165+/-8 and 247+/-10 nM at 3.0x10(-2) mg ml(-1) anti-CD(3) mAb; 201+/-4 and 266+/-9 nM at 5.0x10(-2) mg ml(-1) PHA, in the absence or presence of 1 microM Glu, respectively. The Glu effect showed a bell-shape concentration-dependent relationship, with a maximum (+90+/-3% for anti-CD(3) mAb and +57+/-2% for PHA over Glu-untreated cells) at 1 microM. Non-NMDA receptor agonists (1 microM) showed a greater efficacy (+76+/-2% for (S)-AMPA; +78+/-4% for KA), if compared to NMDA (+46+/-2%), or Glu itself. Ionotropic Glu receptor antagonists completely inhibited the effects of the corresponding specific receptor agonists (1 microM). The IC(50) values calculated were: 0.9 microM for D-AP5; 0.6 microM for (+)-MK801; 0.3 microM for NBQX. Both NBQX and KYNA were able to abolish Glu effect. The IC(50s) calculated were: 3.4 microM for NBQX; 0.4 microM for KYNA. Glu (0.1 - 1 mM) did not change the resting cell proliferation, whereas Glu (1 mM) significant inhibited (-27+/-4%) PHA (1.0x10(-2) mg ml(-1))-induced lymphocyte proliferation at 72 h. In conclusion, human lymphocytes express ionotropic Glu receptors functionally operating as modulators of cell activation.

Relative contribution of different receptor subtypes in the response of neuroblastoma cells to tumor necrosis factor-alpha.

The effect of tumor necrosis factor-alpha (TNF-alpha) on neuronal viability has been investigated in the SK-N-BE neuroblastoma cell line. These cells undergo differentiation upon chronic treatment with retinoic acid. Exposure of SK-N-BE cells to TNF-alpha produced a proliferative response in undifferentiated cells, whereas a reduced cell number was observed in retinoic acid (RA)-differentiated cultures. This biphasic response may be related to the different expression of TNF-alpha receptors (TNFRs); a significant increase in the density of TNFR1 was in fact observed following RA-induced differentiation. Under these conditions, a pronounced increase in the formation of ceramide-1-phosphate (which was prevented by the selective inhibitor of phosphatidylcholine-specific phospholipase C, D609) and an activation of caspase-3 upon TNF-alpha challenge were evident. Selective blockade of each TNFR subtype allowed a more detailed analysis of the effect observed. Preincubation with an anti-TNFR1 antibody prevented the cytotoxic effect of TNF-alpha in RA-differentiated SK-N-BE cells, whereas the anti-TNFR2 antibody blocked the proliferative activity of the cytokine in undifferentiated cultures.

Different expression of TNF-alpha receptors and prostaglandin E(2 )Production in normal and fibrotic lung fibroblasts: potential implications for the evolution of the inflammatory process.

Normal human lung fibroblasts downregulate the production of tumor necrosis factor (TNF)-alpha by activated monocytes through the production of prostaglandin E(2) (PGE(2)), contributing to the local control of the inflammatory process. In this study, we provide evidence that fibroblasts derived from diseased tissue, such as fibrotic lung fibroblasts, exhibit different functional features compared with normal cells, with particular regard to their modulatory role. Indeed, fibrotic fibroblasts (FF) spontaneously produced less PGE(2) (3,300 +/- 410 pg/ml) compared with normal fibroblasts (NF) (7,500 +/- 270 pg/ml) and, as a consequence, they showed a reduced ability to downregulate the production of TNF-alpha by lipopolysaccharide (LPS)- activated monocytes. The percentage of inhibition induced by normal cells on the production of TNF-alpha by LPS-activated monocytes was 61 +/- 5.9%, whereas the inhibitory effect exerted by fibrotic cells was reduced to 32 +/- 4% (P < 0.01). We have also observed that the ability of TNF-alpha to induce PGE(2) was impaired in FF and was related to a reduced expression of cyclooxygenase 2. This was possibly due to the reduction of the expression of TNF receptors (TNFRs) in fibrotic cell lines compared with normal cell lines. Flow cytometry revealed that the mean fluorescence intensity (MFI) of both isoforms of TNFR was significantly lower in FF compared with NF. The MFI of TNFR1 was 3. 55 +/- 0.12 for NF and 1.78 +/- 0.35 for FF (P < 0.001). The MFI of TNFR2 was 1.95 +/- 0.27 for NF and 0.99 +/- 0.16 for FF (P < 0.01). The analysis of the effect of TNF-alpha on some functions associated with collagen metabolism in NF and FF showed an increase of the expression of the receptor for collagen type I (alpha(2)beta(1) integrin) in NF (42 +/- 10%) and an even larger increase in FF (102 +/- 23%) (P < 0.05). Interestingly, unlike NF, TNF-alpha failed to increase matrix metalloproteinase 1 levels in FF and did not cause any growth inhibition in these cells. The reduced capability of fibrotic cells to produce PGE(2) either spontaneously or after TNF-alpha treatment may lead to an unrestrained release of TNF-alpha from activated monocytes and, as a result of the reduced expression of TNFRs, to a different response of these cells to TNF-alpha. These changes may be important in the evolution of the inflammatory process, potentially contributing to its transformation into a chronic and self-perpetuating process.

Selective blockade of mGlu5 metabotropic glutamate receptors protects rat hepatocytes against hypoxic damage.

Western blot analysis of protein extracts from rat liver revealed the presence of the mGlu5 receptor, one of the G-protein-coupled receptors activated by glutamate (named "metabotropic glutamate receptors" or mGlu receptors). mGlu5 expression was particularly high in extracts from isolated hepatocytes, where levels were comparable with those seen in the rat cerebral cortex. The presence of mGlu5 receptors in hepatocytes was confirmed by reverse-transcription polymerase chain reaction (RT-PCR) analysis, immunohistochemistry in neonate or adult rat liver, as well as by immunocytochemical analysis in HepG2 hepatoma cells, where the receptor appeared to be preferentially distributed in cell membranes. Interestingly, mGlu1 receptors (which are structurally and functionally homologous to mGlu5 receptors) were never found in rat liver or hepatocytes. In hepatocytes exposed to anoxic conditions for 90 minutes, glutamate, (1S,3R)-1-aminocyclopentane-1, 3-dicarboxylic acid (1S,3R-ACPD) and quisqualate, which all activate mGlu5 receptors, accelerated the onset and increased the extent of cell damage, while 4-carboxy-3-hydroxyphenylglycine (4C3HPG), an agonist of mGlu2/3 receptors, was inactive. 2-methyl-6-(2-phenyl-1-ethynyl)-pyridine (MPEP), a novel, noncompetitive, highly selective mGlu5 receptor antagonist, not only abolished the toxic effect of 1S,3R-ACPD, but, unexpectedly, was protective by itself against anoxic damage. This suggests that hepatocytes express mGlu5 receptors and that activation of these receptors by endogenous glutamate facilitates the development of anoxic damage in hepatocytes.

Mitogenic effect of nerve growth factor (NGF) in LNCaP prostate adenocarcinoma cells: role of the high- and low-affinity NGF receptors.

We have investigated the effect of nerve growth factor (NGF) in the androgen-dependent, prostate adenocarcinoma LNCaP cell line. Exposure of LNCaP cells to NGF resulted in a significant increase of cell proliferation. The effect was concentration dependent and equally present in serum- or charcoal-stripped serum-supplemented and serum-deprived conditions. The mitogenic action of NGF was accompanied by an enhanced expression of prostate-specific antigen (PSA) and resulted additive to the proliferative effect of dihydrotestosterone. The proliferative effect of NGF appeared to be mediated by the high-affinity NGF receptor, p140trka. Only p140trka, but not the low-affinity NGF receptor, p75LNGFR, was expressed in LNCaP cells; both the proliferative response and the phosphorylation of p140trka upon NGF treatment were prevented by the tyrosine kinase inhibitor K252a. LNCaP cells transiently transfected with the cDNA encoding for p75LNGFR appeared more sensitive to NGF, as demonstrated by the increased number of p75LNGFR-transfected LNCaP cells exposed for 72 h to NGF compared with wild LNCaP cultures. However, p75LNGFR-transfected LNCaP cells rapidly underwent apoptotic death when deprived of NGF. Our study demonstrates the physiological relevance of NGF in the regulation of prostate cell proliferation and the relative contribution of the high- and low-affinity NGF receptors in this control.

Mitotic signaling by beta-amyloid causes neuronal death.

Aggregates of beta-amyloid peptide (betaAP), the main constituent of amyloid plaques in Alzheimer's brain, kill neurons by a not yet defined mechanism, leading to apoptotic death. Here, we report that both full-length betaAP((1-40)) or ((1-42)) and its active fragment betaAP((25-35)) act as proliferative signals for differentiated cortical neurons, driving them into the cell cycle. The cycle followed some of the steps observed in proliferating cells, including induction of cyclin D1, phosphorylation of retinoblastoma, and induction of cyclin E and A, but did not progress beyond S phase. Inactivation of cyclin-dependent protein kinase-4 or -2 prevented both the entry into S phase and the development of apoptosis in betaAP((25-35))-treated neurons. We conclude that neurons must cross the G1/S transition before succumbing to betaAP signaling, and therefore multiple steps within this pathway may be targets for neuroprotective agents.-Copani, A., Condorelli, F., Caruso, A., Vancheri, C., Sala, A., Giuffrida Stella, A. M., Canonico, P. L., Nicoletti, F., Sortino, M. A. Mitotic signaling by beta-amyloid causes neuronal death.

Tumor necrosis factor-alpha induces apoptosis in immortalized hypothalamic neurons: involvement of ceramide-generating pathways.

To investigate possible effects that may contribute, together with a direct action on neurohormone secretion, to the impairment of gonadal axis function during inflammation, we evaluated the effect of TNF alpha on the growth and viability of GT1-7 hypothalamic neurons and the intracellular transduction pathways involved in these effects. TNF alpha caused a reduction of cell number and an induction of apoptotic death. These effects were mimicked by cell-permeable analogs of ceramide and by neutral or acidic sphingomyelinase. Exposure to acidic sphingomyelinase induced a persistent (up to 48 h) reduction of cell growth and apoptosis, whereas the effect of neutral sphingomyelinase was time limited. The involvement of acidic sphingomyelinase in TNF alpha action was demonstrated by the partial prevention of ceramide generation, apoptosis, and reduced cell growth by the inhibitor of the acidic sphingomyelinase-generating pathway, D609, whereas the involvement of ceramide was proved by complete prevention of TNF alpha-induced effects by treatment with okadaic acid at concentrations inhibiting ceramide-dependent protein phosphatase. The present data indicate that TNF alpha, through activation of ceramide-generating pathways, is able to affect GT1-7 cell viability, suggesting an additional effect that may contribute to the global action of this cytokine on neuroendocrine activities.