The European Medicines Agency review of entrectinib for the treatment of adult or paediatric patients with solid tumours who have a neurotrophic tyrosine receptor kinase gene fusions and adult patients with non-small-cell lung cancer harbouring ROS1 rearrangements.

Entrectinib is an inhibitor of the tyrosine kinases TRKA, TRKB, TRKC [all together known as neurotrophic tyrosine receptor kinases (NTRKs)], ROS1 and anaplastic lymphoma kinase (ALK). On 31 July 2020, a conditional marketing authorisation valid through the European Union (EU) was issued for entrectinib for the treatment of adult and paediatric patients 12 years of age and older with NTRK fusion-positive solid tumours that are locally advanced, metastatic or where surgical resection is likely to result in severe morbidity, and who have not received a prior NTRK inhibitor and have no satisfactory therapy; and also for adult patients with ROS1-positive non-small-cell lung cancer (NSCLC) not previously treated with ROS1 inhibitors. The submission was based on three open-label, multicentre, phase I studies (ALKA, STARTRK-1 and STARTRK-NG) and one phase II study (STARTRK-2). In patients with NTRK-positive solid tumours, the objective response rate (ORR) was 63.5% [95% confidence interval (CI) 51.5% to 74.4%] and the median duration of response (DOR) was 12.9 months (95% CI 9.3-not estimable). In patients with ROS1-positive NSCLC, the ORR was 67.1% (95% CI 59.25% to 74.27%) and the median DOR was 15.7 months (95% CI 13.9-28.6 months). The most frequent adverse events were dysgeusia, fatigue, dizziness, constipation, diarrhoea, nausea, increased weight, paraesthesia, increased creatinine, myalgia, peripheral oedema, vomiting, arthralgia, anaemia and increased AST. The aim of this manuscript is to summarise the scientific review of the application leading to regulatory approval of entrectinib in the EU.

Drug utilization, safety, and effectiveness of exenatide, sitagliptin, and vildagliptin for type 2 diabetes in the real world: data from the Italian AIFA Anti-diabetics Monitoring Registry.

BACKGROUND AND AIMS: In Italy, the reimbursed use of incretin mimetics and incretin enhancers was subject to enrollment of patients into a web-based system recording the general demographic and clinical data of patients. We report the utilization data of glucagon-like peptide 1 (GLP1) receptor agonists and dipeptidylpeptidase-4 (DPP4) inhibitors in clinical practice as recorded by the Italian Medicines Agency (AIFA) Monitoring Registry. METHODS AND RESULTS: From February 2008 to August 2010, 75,283 patients with type 2 diabetes were entered into the registry and treated with exenatide, sitagliptin, or vildagliptin. The treatment was administered to patients in a wide range of ages (≥75 years, n = 6125 cases), body mass index (BMI) (≥35 kg/m(2), n = 22,015), and metabolic control (HbA(1c) ≥ 11% ((96 mmol/mol), n = 3151). Overall, 1116 suspected adverse drug reactions were registered, including 12 cases of acute pancreatitis (six on exenatide). Hypoglycemic episodes mainly occurred in combination with sulfonylureas. Treatment discontinuation for the three drugs (logistic regression analysis) was negatively associated with the male gender and positively with baseline HbA1c, diabetes duration, and, limitedly to DPP-4 inhibitors, with BMI. Treatment discontinuation (including loss to follow-up, accounting for 21-26%) was frequent. Discontinuation for treatment failure occurred in 7.7% of cases (exenatide), 3.8% (sitagliptin), and 4.1% (vildagliptin), respectively, corresponding to 27-40% of all discontinuations, after excluding lost to follow-up. HbA1c decreased on average by 0.9-1.0% (9 mmol/mol). Body weight decreased by 3.5% with exenatide and by 1.0-1.5% with DPP-4 inhibitors. CONCLUSIONS: In the real world of Italian diabetes centers, prescriptions of incretins have been made in many cases outside the regulatory limits. Nevertheless, when appropriately utilized, incretins may grant results at least in line with pivotal trials.

Is HCMV vaccine an unmet need? The state of art of vaccine development.

Congenital HCMV infection is the most frequent congenital infection, with an incidence of 0.2- 2.5 percent among all live births. About 11 percent of infected newborns show symptoms at birth, including hepato-splenomegaly, thrombocytopenia, neurologic involvement, hearing impairment and visual deficit. Moreover, 5-25 percent of the asymptomatic congenital HCMV-infected neonates will develop sequelae over months or even years. The relevant social burden, the economic costs of pre-natal screening, post-natal diagnosis, follow-up and possible therapy, although still limited, are the major factors to be considered. Several types of vaccines have been explored in order to develop an effective and safe HCMV vaccine: live attenuated, subunit, vectored, peptide, DNA, and subviral ones, but none are available for use. This review illustrates the different vaccine types studied to date, focusing on the possible vaccination strategy to be implemented once the HCMV vaccine is available, in terms of target population.

Type-3 metabotropic glutamate receptors regulate chemoresistance in glioma stem cells, and their levels are inversely related to survival in patients with malignant gliomas.

Drug treatment of malignant gliomas is limited by the intrinsic resistance of glioma stem cells (GSCs) to chemotherapy. GSCs isolated from human glioblastoma multiforme (GBM) expressed metabotropic glutamate receptors (mGlu3 receptors). The DNA-alkylating agent, temozolomide, killed GSCs only if mGlu3 receptors were knocked down or pharmacologically inhibited. In contrast, mGlu3 receptor blockade did not affect the action of paclitaxel, etoposide, cis-platinum, and irinotecan. mGlu3 receptor blockade enabled temozolomide toxicity by inhibiting a phosphatidylinositol-3-kinase/nuclear factor-κB pathway that supports the expression of O(6)-methylguanine-DNA methyltransferase (MGMT), an enzyme that confers resistance against DNA-alkylating agents. In mice implanted with GSCs into the brain, temozolomide combined with mGlu3 receptor blockade substantially reduced tumor growth. Finally, 87 patients with GBM undergoing surgery followed by adjuvant chemotherapy with temozolomide survived for longer time if tumor cells expressed low levels of mGlu3 receptors. In addition, the methylation state of the MGMT gene promoter in tumor extracts influenced survival only in those patients with low expression of mGlu3 receptors in the tumor. These data encourage the use of mGlu3 receptor antagonists as add-on drugs in the treatment of GBM, and suggest that the transcript of mGlu3 receptors should be measured in tumor specimens for a correct prediction of patients' survival in response to temozolomide treatment.

The origin recognition complex subunit, ORC3, is developmentally regulated and supports the expression of biochemical markers of neuronal maturation in cultured cerebellar granule cells.

The origin recognition complex (ORC) regulates DNA replication. However, some members of the ORC core, such as ORC3 and ORC5, have been implicated in neuronal maturation. In cultured cerebellar granule cells (CGCs), ORC3 mRNA and protein levels increased from 6 to 8days in vitro, a time that coincided with the maximal development of the dendritic arbor. In contrast, expression of ORC5 remained low throughout CGC maturation. Activation of type-4 metabotropic glutamate receptors with the selective enhancer, PHCCC, during a critical time-window (from 4 to 6days in vitro) anticipated the developmental peak of ORC3, increased the expression of two proteins associated with neuronal maturation, i.e. the mitogen-associated protein-2 (MAP-2) and postsynaptic density-95 (PSD-95), as well as dendritic length. siRNA-induced ORC3 knockdown reduced MAP-2 and PSD-95 expression on its own and abrogated the action of PHCCC. We examined whether the maturational effects of ORC3 were mediated by changes in the activity of the monomeric GTP-binding protein, Rho, which is known to regulate granule cell morphology. ORC3 knockdown increased the levels of the GTP-bound active form of Rho, whereas exposure to PHCCC reduced Rho activation. The action of PHCCC was largely attenuated in cultures deprived of ORC3. Finally, granule cell exposure to the Rho-associated kinase inhibitor, Y-27632, abolished the lowering effect of ORC3 knockdown on MAP-2 expression, and increased dendritic length. These data suggest that ORC3 supports neuronal maturation by inhibiting the Rho signaling pathway, and mediates the differentiating activity of mGlu4 receptors in cultured cerebellar granule cells.

mGLU3 metabotropic glutamate receptors modulate the differentiation of SVZ-derived neural stem cells towards the astrocytic lineage.

Neural stem cells (NSCs) isolated from the subventricular zone (SVZ) of postnatal mice, and cultured as neurospheres, expressed functional mGlu3 receptors. Following mitogen withdrawal and plating onto poly-ornitine-coated dishes, cells dissociated from the neurospheres differentiated into GFAP(+) astrocytes (about 85%), and a small percentage of beta-III tubulin(+)-neurons and O1(+)-oligodendrocytes. Activation of mGlu3 receptors with LY379268 (100 nM, applied every other day), during the differentiation period, impaired astrocyte differentiation, favoring the maintenance in culture of proliferating progenitors co-expressing GFAP with the immature markers, Sox1 and nestin. Co-treatment with the preferential mGlu2/3 receptor antagonist, LY341495 (100 nM), reversed this effect. We examined whether mGlu3 receptors could modulate the canonical signaling pathway activated by bone morphogenic proteins (BMPs), which are known to promote astrocyte differentiation of SVZ/NSCs. An acute challenge of cells isolated from the neurospheres with BMP4 (100 ng/mL) led to phosphorylation and nuclear translocation of the transcription factors, Smads. This effect was largely attenuated by the mGlu2/3 receptor agonist, LY379268. The interaction of mGlu3 and BMP4 receptors was mediated by the activation of the mitogen-activated protein kinase (MAPK) pathway. Accordingly, LY379268 failed to affect BMP receptor signaling when combined with the MAPK kinase inhibitor, UO-126 (30 muM). These data raise the intriguing possibility that glutamate regulates differentiation of SVZ/NSCs by activating mGlu3 receptors.

Regulation of GSK-3beta by calpain in the 3-nitropropionic acid model.

Glycogen synthase kinase-3beta (GSK-3beta) is a crucial component in the cascade of events that culminate in a range of neurodegenerative diseases. It is controlled by several pathways, including calpain-mediated cleavage. Calpain mediates in cell death induced by 3-nitropropionic acid (3-NP), but GSK-3beta regulation has not been demonstrated. Here we studied changes in total GSK-3beta protein levels and GSK-3beta phosphorylation at Ser-9 in this model. The 3-NP treatment induced GSK-3beta truncation. This regulation was dependent on calpain activation, since addition of calpeptin to the medium prevented this cleavage. While calpain inhibition prevented 3-NP-induced neuronal loss, inhibition of GSK-3beta by SB-415286 did not. Furthermore, inhibition of cdk5, a known target of calpain involved in 3-NP-induced cell death, also failed to rescue neurons in our model. Our results point to a new target of calpain and indicate possible cross-talk between calpain and GSK-3beta in the 3-NP toxicity pathway. On the basis of our findings, we propose that calpain may modulate 3-NP-induced neuronal loss.

Defective group-II metaboropic glutamate receptors in the hippocampus of spontaneously depressed rats.

Spontaneously depressed flinders sensitive line (FSL) rats showed a reduced expression of mGlu2/3 metabotropic glutamate receptors in the hippocampus, as compared to "non-depressed" flinders resistant line (FRL) rats. No changes in mGlu2/3 receptor protein levels were found in other brain regions, including the amygdala, hypothalamus, and cerebral cortex. Biochemical analysis of receptor signalling supported the reduction of mGlu2/3 receptors in the hippocampus of FSL rats. Accordingly, the selective mGlu2/3 receptor agonist, LY379268 (1microM) reduced forskolin-stimulated cAMP formation by 56% and 32% in hippocampal slices from FRL and FSL rats, respectively. In addition, LY379268 enhanced 3,5-dihydroxyphenylglycine-stimulated inositol phospholipid hydrolysis from 65% to 215% in hippocampal slices from FRL rats, whereas it was inactive in slices from FRL rats. We also examined the behavioural response of FSL rats to systemic injection of LY379268 (0.5mg/kg, i.p., once a day for 1-21 days) by measuring the immobility time in the forced swim test, which is known to be increased in these rats. LY379268 was administered alone or combined with the classical antidepressant, chlorimipramine (10mg/kg, i.p.). LY379268 alone had no effect at any of the selected time-points, whereas chlorimipramine alone reduced the immobility time only after 21 days of treatment. In contrast, when combined with LY379268, chlorimipramine reduced the immobility time during the first 14 days of treatment. These data support the view that mGlu2/3 receptors might be involved in the pathophysiology of depressive disorders, and that pharmacological activation of these receptors may shorten the latency of antidepressant medication.

Type-3 metabotropic glutamate receptors negatively modulate bone morphogenetic protein receptor signaling and support the tumourigenic potential of glioma-initiating cells.

Targeted-therapies enhancing differentiation of glioma-initiating cells (GICs) are potential innovative approaches to the treatment of malignant gliomas. These cells support tumour growth and recurrence and are resistant to radiotherapy and chemotherapy. We have found that GICs express mGlu3 metabotropic glutamate receptors. Activation of these receptors sustained the undifferentiated state of GICs in culture by negatively modulating the action of bone morphogenetic proteins, which physiologically signal through the phosphorylation of the transcription factors, Smads. The cross-talk between mGlu3 receptors and BMP receptors was mediated by the activation of the mitogen-activated protein kinase pathway. Remarkably, pharmacological blockade of mGlu3 receptors stimulated the differentiation of cultured GICs into astrocytes, an effect that appeared to be long lasting, independent of the growth conditions, and irreversible. In in vivo experiments, a 3-month treatment with the brain-permeant mGlu receptor antagonist, LY341495 limited the growth of infiltrating brain tumours originating from GICs implanted into the brain parenchyma of nude mice. While clusters of tumour cells were consistently found in the brain of control mice, they were virtually absent in a large proportion of mice treated with LY341495. These findings pave the way to a new non-cytotoxic treatment of malignant gliomas based on the use of mGlu3 receptor antagonists.

Metabotropic glutamate receptors regulate differentiation of embryonic stem cells into GABAergic neurons.

Mouse embryonic stem (ES) cells were stimulated to differentiate either as adherent monolayer cultures in DMEM/F12 supplemented with N2/B27, or as floating embryoid bodies (EBs) exposed to 1 microM retinoic acid (RA) for 4 days, starting from 4 DIV, and subsequently re-plated in DMEM/F12 medium. Adherent monolayer cultures of ES cells expressed mGlu5 receptors throughout the entire differentiation period. Selective pharmacological blockade of mGlu5 receptors with methyl-6-(phenylethynyl)-pyridine (MPEP) (1 microM, added once a day) accelerated the appearance of the neuronal marker, beta-tubulin. In addition, treatment with MPEP increased the number of cells expressing glutamate decarboxylase-65/67 (GAD(65/67)), a marker of GABAergic neurons. In floating EBs, mGlu5 receptors are progressively replaced by mGlu4 receptors. The orthosteric mGlu4/6/7/8 receptor agonist, L-2-amino-4-phosphonobutanoate (L-AP4), or the selective mGlu4 receptor enhancer, PHCCC,--both combined with RA at concentrations of 30 microM--increased the expression of both beta-tubulin and GAD(65/67), inducing the appearance of fully differentiated neurons that released GABA in response to membrane depolarization. We conclude that mGlu receptor subtypes regulate neuronal differentiation of ES cells in a context-dependent manner, and that subtype-selective ligands of these receptors might be used for the optimization of in vitro protocols aimed at producing GABAergic neurons from ES cells.

Synergism between fluoxetine and the mGlu2/3 receptor agonist, LY379268, in an in vitro model for antidepressant drug-induced neurogenesis.

We examined the interaction between the selective serotonin reuptake inhibitor, fluoxetine, and group-II metabotropic glutamate (mGlu) receptors using progenitor cells isolated from cultured cerebellar granule cells, considered as an in vitro model of antidepressant-drug induced neurogenesis. These cells expressed mGlu3 receptors negatively coupled to adenylyl cyclase. A 72-h treatment with either fluoxetine or low concentrations of mGlu2/3 receptor agonists (LY379268 or 2R,4R-APDC) enhanced cell proliferation. The action of fluoxetine was mediated by the activation of 5-HT(1A) receptors. We found a strong synergism between fluoxetine and LY379268 in enhancing cell proliferation and inhibiting cAMP formation. The increased cell proliferation induced by fluoxetine+LY379268 was abrogated by the cAMP analogue, 8-Br-cAMP, as well as by drugs that inhibit the mitogen-activated protein kinase and phosphatidyilinositol-3-kinase pathways. Interestingly, fluoxetine and LY379268 also acted synergistically in promoting neuronal differentiation when progenitor cells were incubated in the presence of serum. These data support the hypothesis that a combination between classical antidepressants and mGlu2/3 receptor agonists may be helpful in the experimental treatment of depression.

Expression of the Wnt inhibitor Dickkopf-1 is required for the induction of neural markers in mouse embryonic stem cells differentiating in response to retinoic acid.

Cultured mouse D3 embryonic stem (ES) cells differentiating into embryoid bodies (EBs) expressed several Wnt isoforms, nearly all isotypes of the Wnt receptor Frizzled and the Wnt/Dickkopf (Dkk) co-receptor low-density lipoprotein receptor-related protein (LRP) type 5. A 4-day treatment with retinoic acid (RA), which promoted neural differentiation of EBs, substantially increased the expression of the Wnt antagonist Dkk-1, and induced the synthesis of the Wnt/Dkk-1 co-receptor LRP6. Recombinant Dkk-1 applied to EBs behaved like RA in inducing the expression of the neural markers nestin and distal-less homeobox gene (Dlx-2). Recombinant Dkk-1 was able to inhibit the Wnt pathway, as shown by a reduction in nuclear beta-catenin levels. Remarkably, the antisense- or small interfering RNA-induced knockdown of Dkk-1 largely reduced the expression of Dlx-2, and the neuronal marker beta-III tubulin in EBs exposed to RA. These data suggest that induction of Dkk-1 and the ensuing inhibition of the canonical Wnt pathway is required for neural differentiation of ES cells.

Induced sputum, exhaled breath condensate and nasal lavage fluid in electroplating workers exposed to chromium.

Occupational exposure to chromium may cause airway inflammation and bronchial asthma. In this study we investigated the effect of chromium on the respiratory tract of exposed and non-exposed electroplating workers using spirometry and analysis of induced sputum (IS), exhaled breath condensate (EBC) and nasal lavage fluid (NLF). In both groups spirometry was normal; chromium in induced sputum was higher in exposed workers (7.90 +/- 0.855 microg/L, vs 1.78 +/- 0.075 microg/L; p<0.001); no significant difference was found in induced sputum cellularity. Median nitrite concentration in EBC was significantly higher in exposed subjects (4.35 micromol/L, 5 degrees -95 degrees percentile: 1.88-10.13 vs 0.11 micromol/L, 5-95 percentile: 0-0.72) (p<0.001). IL-6 and TNF-alpha were not detectable in EBC. Median IL-6 concentration in nasal lavage fluid was higher in exposed workers (5.72 pg/ml, 5-95 percentile: 0-65.25 pg/ml vs 0.28 pg/ml, 5-95 percentile: 0-1.7 pg/ml) (p<0.01). No differences in Eosinophil Cationic Protein concentration were found. TNF-alpha was not detectable in NLF. Chromium in induced sputum correlated with nitrites in EBC. For the first time three non-invasive methods were used to assess changes in respiratory tract in workers exposed to chromium. The results suggest chromium exerts an inflammatory/irritative action on airways.

Metabotropic glutamate receptors and neuroadaptation to antidepressants: imipramine-induced down-regulation of beta-adrenergic receptors in mice treated with metabotropic glutamate 2/3 receptor ligands.

Antidepressant drugs have a clinical latency that correlates with the development of neuroadaptive changes, including down-regulation of beta-adrenergic receptors in different brain regions. The identification of drugs that shorten this latency will have a great impact on the treatment of major depressive disorders. We report that the time required for the antidepressant imipramine to reduce the expression of beta-adrenergic receptors in the hippocampus is reduced by a co-administration with centrally active ligands of type 2/3 metabotropic glutamate (mGlu2/3) receptors. Daily treatment of mice with imipramine alone (10 mg/kg, i.p.) reduced the expression of beta-adrenergic receptors in the hippocampus after 21 days, but not at shorter times, as assessed by western blot analysis of beta1-adrenergic receptors and by the amount of specifically bound [3H]CGP-12177, a selective beta-adrenergic receptor ligand. Down-regulation of beta-adrenergic receptors occurred at shorter times (i.e. after 14 days) when imipramine was combined with low doses (0.5 mg/kg, i.p.) of the selective mGlu2/3 receptor agonist LY379268, or with the preferential mGlu2/3 receptor antagonist LY341495 (1 mg/kg, i.p.). Higher doses of LY379268 (2 mg/kg, i.p.) were inactive. This intriguing finding suggests that neuroadaptation to imipramine--at least as assessed by changes in the expression of beta1-adrenergic receptors--is influenced by drugs that interact with mGlu2/3 receptors and stimulates further research aimed at establishing whether any of these drugs can shorten the clinical latency of classical antidepressants.

Endogenous activation of metabotropic glutamate receptors supports the proliferation and survival of neural progenitor cells.

The use of neural progenitor cells (NPCs) is limited by the incomplete knowledge of the extracellular signals regulating their proliferation and survival. We report that cultured mouse NPCs express functional mGlu3 and mGlu5 metabotropic glutamate receptors. Pharmacological blockade of both receptors reduced NPC proliferation and survival, whereas activation of mGlu5 receptors substantially enhanced cell proliferation. Adult mice lacking mGlu5 receptors or treated with mGlu5 or mGlu3 receptor antagonists showed a dramatic reduction in the number of dividing neuroprogenitors present in the subventricular zone and in the dentate gyrus of the hippocampus. These data disclose a novel function of mGlu receptors and offer new potential strategies for the optimization of cell replacement therapy in neurodegenerative disorders.

Interactions between ephrin-B and metabotropic glutamate 1 receptors in brain tissue and cultured neurons.

We examined the interaction between ephrins and metabotropic glutamate (mGlu) receptors in the developing brain and cultured neurons. EphrinB2 coimmunoprecipitated with mGlu1a receptors, in all of the brain regions examined, and with mGlu5 receptors in the corpus striatum. In striatal slices, activation of ephrinB2 by a clustered form of its target receptor, EphB1, amplified the mGlu receptor-mediated stimulation of polyphosphoinositide (PI) hydrolysis. This effect was abolished in slices treated with mGlu1 or NMDA receptor antagonists but was not affected by pharmacological blockade of mGlu5 receptors. An interaction among ephrinB2, mGlu1 receptor, and NMDA was supported by the following observations: (1) the NR1 subunit of NMDA receptors coimmunoprecipitated with mGlu1a receptors and ephrinB2 in striatal lysates; (2) clustered EphB1 amplified excitatory amino acid-stimulated PI hydrolysis in cultured granule cells grown under conditions that favored the expression of mGlu1a receptors; and (3) clustered EphB1 amplified the enhancing effect of mGlu receptor agonists on NMDA toxicity in cortical cultures, and its action was sensitive to mGlu1 receptor antagonists. Finally, fluorescence resonance energy transfer and coclustering analysis in human embryonic kidney 293 cells excluded a physical interaction between ephrinB2 and mGlu1a (or mGlu5 receptors). A functional interaction between ephrinB and mGlu1 receptors, which likely involves adaptor or scaffolding proteins, might have an important role in the regulation of developmental plasticity.

PHCCC, a specific enhancer of type 4 metabotropic glutamate receptors, reduces proliferation and promotes differentiation of cerebellar granule cell neuroprecursors.

Exposure of immature rat cerebellar granule cell cultures to the type 4 metabotropic glutamate (mGlu4) receptor enhancer N-phenyl-7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxamide (PHCCC) reduced [3H]thymidine incorporation. Its action was sensitive to the growth conditions and was attenuated by two mGlu4 receptor antagonists. An antiproliferative action of PHCCC was also seen in cultures from wild-type, but not mGlu4, knock-out mice. At least in rat cultures, PHCCC was not neurotoxic and enhanced neuritogenesis. Although PHCCC reduced the increase in cAMP formation and phospho-AKT levels induced by forskolin, none of these transduction pathways significantly contributed to the reduction of [3H]thymidine incorporation. Interestingly, PHCCC reduced the expression of Gli-1, a transcription factor that mediates the mitogenic action of Sonic hedgehog. Finally, we treated newborn rats with PHCCC either intracerebrally (infusion of 5 nmol/2 microl in the cerebellar region once every other day) or systemically (5 mg/kg, i.p., once daily) from postnatal days 3-9. Local infusion of PHCCC induced substantial changes in the morphology of the developing cerebellum. In contrast, systemic injection of PHCCC induced only morphological abnormalities of the cerebellar lobule V, which became visible 11 d after the end of the treatment. These data suggest that mGlu4 receptors are involved in the regulation of cerebellar development.

Metabotropic receptors as targets for drugs of potential use in the treatment of neuropathic pain.

Glutamate is the major neurotransmitter in the mammalian central nervous system and plays a pivotal role in both acute and chronic pain. The actions of glutamate are mediated by two receptor families: ionotropic glutamate receptors (iGluRs), and metabotropic glutamate receptors (mGluRs). Activation of glutamate receptor can elicit both hyperalgesic and analgesic effects. Eight mGluRs subtypes (mGluR1-mGluR8) have been identified and classified into three groups. Among these, group I mGluRs (mGlu1 and -5) have been implicated in the processes of central sensitization and persistent nociception, whereas activation of group II mGluRs (mGlu2/3) is effective against neuropathic or inflammatory pain. In this review we focus on the role of mGlu2/3 in the modulation of persistent pain, and on their potential use as drug targets in pain management.

Activation of Fas receptor is required for the increased formation of the disialoganglioside GD3 in cultured cerebellar granule cells committed to apoptotic death.

Apoptosis was induced in cultured cerebellar granule cells by lowering extracellular K+ concentrations (usually from 25 to 10 mM). The apoptotic phenotype was preceded by an early and transient increase in the intracellular levels of the disialoganglioside, GD3, which behaves as a putative pro-apoptotic factor. We examined whether activation of Fas receptor mediates the increase in GD3 formation in granule cells committed to die. Degenerating granule cells showed increased expression of both Fas receptor and its ligand (Fas-L), at times that coincided with the increase in GD3 levels and the induction of GD3 synthase mRNA. Addition of neutralizing anti-Fas-L antibodies reduced the extent of 'low-K+'-induced apoptosis and abolished the increase in GD3 levels and GD3 synthase mRNA. Similar reductions were observed in cultures prepared from gld or lpr mice, which harbor loss-of-function mutations of Fas-L and Fas receptor, respectively. In addition, exogenous application of soluble Fas-L further enhanced both the increase in GD3 formation and cell death in cultured granule cells switched from 25 into 10 mM K+. We conclude that activation of Fas receptor is entirely responsible for the increase in GD3 levels and contributes to the development of apoptosis by trophic deprivation in cultured cerebellar granule cells.

The mGlu5 metabotropic glutamate receptor is expressed in zones of active neurogenesis of the embryonic and postnatal brain.

Metabotropic glutamate (mGlu) receptors have been implicated in the regulation of developmental plasticity. Here, we examined the expression of mGlu1a-b, -2, -3, -4a-b, and -5a receptor subtypes from embryonic day 12 (E12) to the early and late postnatal life. While all transcripts (with the exception of mGlu4 mRNA) were detected prenatally, only the mGlu5 receptor protein was found in detectable amounts in the embryonic brain. Immunohistochemical analysis showed that the mGlu5 receptor was mainly expressed by cells surrounding the ventricles at E15, whereas it was more diffusely expressed at E18. In the postnatal life, besides its classical expression sites, the mGlu5 receptor was found in zones of active neurogenesis such as the external granular layer (EGL) of the cerebellar cortex and the subventricular zone. In these regions, the presence of actively proliferating progenitor cells was detected by BrdU staining. No other subtype (among those we have examined) was found to be expressed in regions enriched of BrdU(+) cells. These data suggest a role for mGlu5 receptors in the early brain development and in basic cellular processes such as proliferation and/or differentiation.