Unexpected Ca2+-mobilization of oxaliplatin via H1 histamine receptors.

Oxaliplatin is a widely used chemotherapeutic drug and represents the cornerstone of colorectal cancer therapy, in combination with 5-fluorouracil and folinic acid. As with many chemotherapeutic agents, its use is associated with a number of side effects, ranging from hypersensitivity reactions to haematological dyscrasias. Oxaliplatin also induces acute and chronic peripheral neuropathy. While it is likely that the haematological side effects are associated with its anti-proliferative effects and with the ability to form DNA adducts, the molecular mechanisms underlying peripheral neuropathy and hypersensitivity reactions are poorly understood, and therefore the choice of adequate supportive therapies is largely empirical. Here we show that an acute low dose oxaliplatin application on DRG neurons is able to induce an increase in intracellular calcium that is dependent on the Histamine 1 receptor (H1). Oxaliplatin-induced intracellular calcium rises are blocked by two selective H1 antagonist, as well as by U73122, a PLC inhibitor, and by 2-APB, a non-specific IP3 receptor blocker. Moreover, expression of the H1 receptor on HEK293 t cells unmasks an oxaliplatin-induced Ca2+-rise. Last, activation of H1 via either histamine or oxaliplatin activates TRPV1 receptors, a mechanism that has been associated with itch. These data, together with literature data that has shown that anti-histamine agents reduce the incidence of oxaliplatin-induced hypersensitivity, may provide a molecular mechanism of this side effect in oncological patients.

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.

Pharmacological enhancement of mGlu5 receptors rescues behavioral deficits in SHANK3 knock-out mice.

SHANK3 (also called PROSAP2) genetic haploinsufficiency is thought to be the major cause of neuropsychiatric symptoms in Phelan-McDermid syndrome (PMS). PMS is a rare genetic disorder that causes a severe form of intellectual disability (ID), expressive language delays and other autistic features. Furthermore, a significant number of SHANK3 mutations have been identified in patients with autism spectrum disorders (ASD), and SHANK3 truncating mutations are associated with moderate to profound ID. The Shank3 protein is a scaffold protein that is located in the postsynaptic density (PSD) of excitatory synapses and is crucial for synapse development and plasticity. In this study, we investigated the molecular mechanisms associated with the ASD-like behaviors observed in Shank3Δ11-/- mice, in which exon 11 has been deleted. Our results indicate that Shank3 is essential to mediating metabotropic glutamate receptor 5 (mGlu5)-receptor signaling by recruiting Homer1b/c to the PSD, specifically in the striatum and cortex. Moreover, augmenting mGlu5-receptor activity by administering 3-Cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide ameliorated the functional and behavioral defects that were observed in Shank3Δ11-/- mice, suggesting that pharmaceutical treatments that increase mGlu5 activity may represent a new approach for treating patients that are affected by PMS and SHANK3 mutations.

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.

Metabotropic glutamate receptor 5 in Down's syndrome hippocampus during development: increased expression in astrocytes.

Metabotropic glutamate receptor 5 (mGluR5) is highly expressed throughout the forebrain and hippocampus. Several lines of evidence support the role of this receptor in brain development and developmental disorders, as well as in neurodegenerative disorders like Alzheimer's disease (AD). In the present study, the expression pattern of mGluR5 was investigated by immunocytochemistry in the developing hippocampus from patients with Down's syndrome (DS) and in adults with DS and AD. mGluR5 was expressed in developing human hippocampus from the earliest stages tested (9 gestational weeks), with strong expression in the ventricular/subventricular zones. We observed a consistent similar temporal and spatial neuronal pattern of expression in DS hippocampus. However, in DS we detected increased prenatal mGluR5 expression in white matter astrocytes, which persisted postnatally. In addition, in adult DS patients with widespread ADassociated neurodegeneration (DS-AD) increased mGluR5 expression was detected in astrocytes around amyloid plaque. In vitro data confirm the existence of a modulatory crosstalk between amyloid-ß and mGluR5 in human astrocytes. These findings demonstrate a developmental regulation of mGluR5 in human hippocampus and suggest a role for this receptor in astrocytes during early development in DS hippocampus, as well as a potential contribution to the pathogenesis of ADassociated pathology.

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.

Amyloid-ß and Alzheimer's disease type pathology differentially affects the calcium signalling toolkit in astrocytes from different brain regions.

The entorhinal-hippocampal circuit is severely affected in Alzheimer's disease (AD). Here, we demonstrate that amyloid-ß (Aß) differentially affects primary cultured astrocytes derived from the entorhinal cortex (EC) and from the hippocampus from non-transgenic controls and 3xTg-AD transgenic mice. Exposure to 100 nM of Aß resulted in increased expression of the metabotropic glutamate receptor type 5 (mGluR5) and its downstream InsP3 receptor type 1 (InsP3R1) in hippocampal but not in EC astrocytes. Amplitudes of Ca(2+) responses to an mGluR5 agonist, DHPG, and to ATP, another metabotropic agonist coupled to InsP3Rs, were significantly increased in Aß-treated hippocampal but not in EC astrocytes. Previously we demonstrated that senile plaque formation in 3xTg-AD mice triggers astrogliosis in hippocampal but not in EC astrocytes. The different sensitivities of the Ca(2+) signalling toolkit of EC versus hippocampal astrocytes to Aß may account for the lack of astrogliosis in the EC, which in turn can explain the higher vulnerability of this region to AD.

Severe acute nephrotoxicity in a kidney transplant patient despite low tacrolimus levels: a possible interaction between donor and recipient genetic polymorphisms.

WHAT IS KNOWN AND OBJECTIVE: Tacrolimus has a narrow therapeutic index and shows large interindividual variations in pharmacokinetics, which may be partly explained by genetic variability in metabolic enzymes of the cytochrome P450 (mainly CYP3A4 and CYP3A5) and transport P-glycoprotein (encoded by the ABCB1 gene). Genetic variability in the expression of biotransformation enzymes and drug transporters may also predispose individuals to tacrolimus-induced nephrotoxicity. CASE SUMMARY: We report a case of severe biopsy-proven Tacrolimus (TAC) nephrotoxicity that occurred 1 month after renal transplantation despite persistently low TAC levels. The donor genotype was CYP3A5*3/*3 (loss-of-function genotype), whereas that of the recipient was CYP3A5*1/*3. The donor and recipient genotypes did not differ with respect to either CYP3A4 rs35599367C>T (both were CC homozygotes) or ABCB1 gene polymorphisms (both TT homozygotes for the 1236C>T polymorphism and CT heterozygotes for the 3435C>T polymorphism). WHAT IS NEW AND CONCLUSION: This case study suggests that donor/recipient genetic mismatch in metabolic enzymes may have an important role in modulating tacrolimus nephrotoxicity. It provides a possible explanation for the intriguing observation that for a subset of patients, cumulative TAC doses appear to correlate better with nephrotoxicity than trough levels.

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.

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.

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.

A transport mechanism for NAADP in a rat basophilic cell line.

NAADP is a second messenger that releases Ca2+ from intracellular stores. Surprisingly, it has been recently shown that extracellular application of NAADP is capable of inducing intracellular Ca2+ release. This is particularly important since the only mammalian enzymes known to catalyze the synthesis of this second messenger are located extracellularly. In the present manuscript, we have investigated whether mammalian cells possess a transport system capable of transporting this highly charged molecule into cells. Indeed, in RBL-2H3 cells, a rat basophilic cell line, and in SK-N-BE cells, a neuroblastoma cell line, [32P]NAADP is efficiently transported inside cells. NAADP transport is Na+ and Ca2+ dependent, is partially blocked by dipyridamole, but is unaffected by nitrobenzylthioinosine. RBL-2H3 cells also transport [32P]cADPR, but the differences in the pharmacological profile suggest that NAADP transport proceeds by a novel mechanism. Lastly, extracellular application of NAADP, but not NADP, induced a raise in intracellular Ca2+. This is the first demonstration that NAADP is transported into cells and highlights the possibility that, alongside a second messenger, NAADP might also act as an autocrine/paracrine signal.

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.

Role of the nicotinic acid group in NAADP receptor selectivity.

Nicotinic acid adenine dinucleotide phosphate (NAADP) has been shown to be an intracellular Ca2+-releasing messenger in a wide variety of systems to date. Its actions are both potent and highly specific despite differing structurally from the endogenous cellular co-factor and its precursor, NADP, only in the substitution of a hydroxyl for the amine group at the 3' position of the pyridine ring. This substitution allows NAADP to bind to a membrane-localized binding site in sea urchin egg homogenates with an IC50 at least 1000-fold greater than that of NADP as measured by competition radioligand binding assays. This suggests that the NAADP receptor protein must include certain features in the NAADP binding site that regulate this specificity. In order to investigate this interaction, we synthesised a series of NAADP analogues differing from NAADP at the 3' position of the pyridine ring that included both simple carboxylic acid analogues as well as a series of chemical isosters. We then investigated both their affinity for the NAADP binding site in sea urchin egg homogenates and their ability to activate the NAADP sensitive Ca2+ channel. We hereby show that a negative charge at the 3' position is an important determinant of affinity but the protein displays a large tolerance for the size of the group. Furthermore, the protein does not easily accommodate multiple charged groups or large uncharged groups.

NAADP receptors are present and functional in the heart.

Alongside the well-studied inositol 1,4,5 trisphosphate and ryanodine receptors, evidence is gathering that a new intracellular release mechanism, gated by the pyridine nucleotide nicotinic acid adenine dinucleotide phosphate (NAADP), is present in numerous organisms, ranging from plant to mammalian cells (reviewed in [1]). Most cells have been shown to express at least two Ca(2+)-release mechanisms controlled by different messengers, and this can lead to redundancy, convergence, or divergence of responses. One exception appears to be muscle and heart contractile tissues. Here, it is thought that the dominant intracellular channel is the ryanodine receptor, while IP(3) receptors are poorly expressed and their role appears to be negligible. We now report that NAADP receptors are functional and abundant in cardiac microsomes. NAADP binds specifically and with high affinity (130 pM and 4 nM) to two sites on cardiac microsomes and releases Ca(2+) with an apparent EC(50) of 323 +/- 14 nM. Furthermore, binding experiments show that this receptor displays both positive and negative cooperativity, a peculiarity unique among intracellular Ca(2+) channels. Therefore, we show that the heart possesses multiple mechanisms to increase the complexity of Ca(2+) signaling and that NAADP may be integral in the functioning of this organ.

Characterization of NAADP(+) binding in sea urchin eggs.

Nicotinic acid adenine dinucleotide phosphate (NAADP(+)) is a pyridine nucleotide which has been shown to release Ca(2+) from intracellular membranes in echinoderms, Ascidiae, mammals, and plants. NAADP releases Ca(2+) via a mechanism independent of ryanodine and inositol 1,4,5-trisphosphate (IP(3)) receptors and the NAADP(+) receptor is likely to be located on a separate organelle. We have investigated the binding characteristics of NAADP(+) to its receptor in sea urchin egg homogenates. NAADP(+) binds to a saturable membrane-bound site with high affinity (K(d) = 193 +/- 35. 7 pM). NAADP(+) associates to its receptor with a t(1/2) of approximately 7 min while dissociation does not occur during the time course of the experiment. Furthermore, NAD(+), NAAD(+), ADP, or ATP cannot displace NAADP(+) binding. The structurally related molecules NADP(+) and NADPH displayed a markedly lower affinity for the binding site with K(d)'s 500- and 25,000-fold higher than NAADP(+), respectively. This discrepancy between oxidized and reduced forms of NADP(+) might suggest that NAADP(+) signaling is itself regulated by the redox state of the cell.

Nicotinic acid adenine dinucleotide phosphate-induced Ca(2+) release. Interactions among distinct Ca(2+) mobilizing mechanisms in starfish oocytes.

An intracellular mechanism activated by nicotinic acid adenine dinucleotide phosphate (NAADP(+)) contributes to intracellular Ca(2+) release alongside inositol 1,4,5-trisphosphate (Ins-P(3)) and ryanodine receptors. The NAADP(+)-sensitive mechanism has been shown to be operative in sea urchin eggs, ascidian eggs, and pancreatic acinar cells. Furthermore, most mammalian cell types can synthesize NAADP(+), with nicotinic acid and NADP(+) as precursors. In this contribution, NAADP(+)-induced Ca(2+) release has been investigated in starfish oocytes. Uncaging of injected NAADP(+) induced Ca(2+) mobilization in both immature oocytes and in oocytes matured by the hormone 1-methyladenine (1-MA). The role of extracellular Ca(2+) in NAADP(+)-induced Ca(2+) mobilization, which was minor in immature oocytes, was instead essential in mature oocytes. Thus, the NAADP(+)-sensitive Ca(2+) pool, which is known to be distinct from those sensitive to inositol 1,4,5-trisphosphate or cyclic ADPribose, apparently migrated closer to (or became part of) the plasma membrane during the maturation process. Inhibition of both Ins-P(3) and ryanodine receptors, but not of either alone, substantially inhibited NAADP(+)-induced Ca(2+) mobilization in both immature and mature oocytes. The data also suggest that NAADP(+)-induced Ca(2+) mobilization acted as a trigger for Ca(2+) release via Ins-P(3) and ryanodine receptors.