Design and application of antisense oligonucleotides in cell culture, in vivo, and as therapeutic agents

NF-Kappa-B Downregulation Strategies in Head and Neck Cancer Treatment

OBJECTIVE: Multiple biochemical and genetic strategies were used to downregulate early response gene NF-κB, whose activation controls squamous cell cancer-associated pathways.

STUDY DESIGN: NA cells, an oral cavity squamous cell cancer with high NF-κB activity, were cultured with biochemical NF-κB inhibitors TPCK and Calpain I inhibitor, as well as specific NF-κB antisense oligonucleotides. Cell proliferation was measured, as was NF-κB downregulation using functional luciferase reporter genes and electromobility shift assays.

RESULTS: Significant downregulation of cell proliferation and NF-κB functional activity were demonstrated with either biochemical inhibitor, as well as the antisense oligonucleotides; however, additional nonspecific toxicities were observed with control antisense oligonucleotides.

CONCLUSION AND SIGNIFICANCE: NF-κB is a potential target for squamous cancer treatment, as it is constitutively upregulated in vitro. Biochemical inhibition of NF-κB may be a viable treatment strategy for head and neck squamous cancers.

Use of ribozymes and antisense oligodeoxynucleotides to investigate mechanisms of drug resistance

Chemotherapy can cure a number of human cancers but resistance (either intrinsic or acquired) remains a significant problem in many patients and in many types of solid tumour. Combination chemotherapy (using drugs with different cellular targets/mechanisms) was introduced in order to kill cells which had developed resistance to a specific drug, and to allow delivery of a greater total dose of anti-cancer chemicals by combining drugs with different side-effects (Pratt et al., 1994). Nearly all anti-cancer drugs kill tumour cells by activating an endogenous bio-chemical pathway for cell suicide, known as programmed cell death or apoptosis.

Treatment of malignant gliomas with TGF-beta2 antisense oligonucleotides

Antisense oligodeoxynucleotides (AS-ODNs) have been widely used to determine gene function, validate drug targets and as novel therapeutics for human diseases. In this review, we describe the development of AS-ODNs, including their modifications, pharmacokinetics and toxicity in animal models and humans, and their preclinical and clinical development in the therapy of human high-grade gliomas. The most advanced AS-ODN for the therapy of high-grade gliomas is a phosphorothioate-modified AS-ODN, AP 12009 (trabedersen), which targets mRNA encoding TGF-beta2. AP 12009 is administered intratumorally using convection-enhanced delivery. A series of Phase I and II clinical trials have evaluated the toxicity profile and optimal dose of the substance. A randomized, controlled international Phase III study was initiated in March 2009 and will compare trabedersen 10 microM versus conventional alkylating chemotherapy in patients with recurrent or refractory anaplastic astrocytoma after standard radio- and chemotherapy.

Antisense therapeutics for tumor treatment: the TGF-beta2 inhibitor AP 12009 in clinical development against malignant tumors

Overexpression of the cytokine transforming growth factor-beta 2 (TGF-beta2) is a hallmark of various malignant tumors including pancreatic carcinoma, malignant glioma, metastasizing melanoma, and metastatic colorectal carcinoma. This is due to the pivotal role of TGF-beta2 as it regulates key mechanisms of tumor development, namely immunosuppression, metastasis, angiogenesis, and proliferation. The antisense technology is an innovative technique offering a targeted approach for the treatment of different highly aggressive tumors and other diseases. Antisense oligonucleotides are being developed to inhibit the production of disease-causing proteins at the molecular level. The immunotherapeutic approach with the phosphorothioate oligodeoxynucleotide AP 12009 for the treatment of malignant tumors is based on the specific inhibition of TGF-beta2. After providing preclinical proof of concept, the safety and efficacy of AP 12009 were assessed in clinical phase I/II open-label dose-escalation studies in recurrent or refractory high-grade glioma patients. Median survival time after recurrence exceeded the current literature data for chemotherapy. Currently, phase I/II study in advanced pancreatic carcinoma, metastatic melanoma, and metastatic colorectal carcinoma and a phase IIb study in recurrent or refractory high-grade glioma are ongoing. The preclinical as well as the clinical results implicate targeted TGF-beta2 suppression as a promising therapeutic approach for malignant tumor therapy.

Computational genes: a tool for molecular diagnosis and therapy of aberrant mutational phenotype

Background

A finite state machine manipulating information-carrying DNA strands can be used to perform autonomous molecular-scale computations at the cellular level.

Results

We propose a new finite state machine able to detect and correct aberrant molecular phenotype given by mutated genetic transcripts. The aberrant mutations trigger a cascade reaction: specific molecular markers as input are released and induce a spontaneous self-assembly of a wild type protein or peptide, while the mutational disease phenotype is silenced. We experimentally demostrated in in vitro translation system that a viable protein can be autonomously assembled.

Conclusion

Our work demostrates the basic principles of computational genes and particularly, their potential to detect mutations, and as a response thereafter administer an output that suppresses the aberrant disease phenotype and/or restores the lost physiological function.

Agents that act by different mechanisms modulate the activity of protein kinase CβII isozyme in the rat spinal cord during peripheral inflammation

Hyperalgesia following unilateral complete Freund's adjuvant-induced inflammation was characterized by paw withdrawal latency to thermal stimulus. Paw withdrawal latencies were significantly shorter on the complete Freund's adjuvant-treated paw than on the contralateral paw of the complete Freund's adjuvant- and the sham-treated rats. Total cytosolic protein kinase C activity in the lumbar enlargement was unchanged on the sides of the spinal cord ipsi- and contra-lateral to the inflamed paw. Membrane-associated activities of protein kinase Calpha, protein kinase CbetaI and protein kinase Cgamma did not change significantly on the sides of the cord ipsi- and contra-lateral to the inflammation. However, membrane-associated activity of protein kinase CbetaII was increased in the cord section ipsilateral to the inflammation, suggesting that increased translocation/activation of protein kinase CbetaII is related to thermal hyperalgesia. Dextrorphan (an N-methyl-D-aspartate receptor antagonist), L-703,606 (an NK-1 receptor antagonist) and an antisense oligodeoxynucleotide for a selective knockdown of protein kinase Cbeta, reduced complete Freund's adjuvant-induced hyperalgesia, and reversed significant changes in the membrane activity of protein kinase CbetaII on the spinal cord section ipsilateral to the inflamed paw. Dextrorphan and protein kinase Cbeta antisense oligodeoxynucleotide were effective in reversing complete Freund's adjuvant-induced increase in the activity of protein kinase CbetaII ipsilateral to the inflammation at all the doses tested, but L-703,606 was effective only at the highest dose. Furthermore, in the presence of inflammatory stimulus, dextrorphan and L-703,606 did not alter the activities of membrane-associated protein kinase Calpha, protein kinase CbetaI, and protein kinase Cgamma in the section of the spinal cord ipsi- and contra-lateral to the inflammation. Protein kinase Cbeta antisense oligodeoxynucleotide had no significant effect on the membrane-associated activities of protein kinase Calpha and protein kinase Cgamma, but decreased the activities of both protein kinase CbetaI and protein kinase CbetaII and the expression of protein kinase Cbeta isozyme in the spinal cord. The data provide evidence that a common molecular event that converges to initiate and maintain hyperalgesia may include the translocation and activation of protein kinase CbetaII in the spinal dorsal horn.

Inhibiting BDNF expression by antisense oligonucleotide infusion causes loss of nigral dopaminergic neurons

Brain derived neurotrophic factor (BDNF) expression is significantly reduced in the Parkinson's disease substantia nigra. This neurotrophin has potent affects on dopaminergic neuron survival protecting them from the neurotoxins MPTP and 6-hydroxydopamine (6-OHDA) commonly used to create animal models of Parkinson's disease and also promoting dopaminergic axonal sprouting. In this study, we demonstrate that an antisense oligonucleotide infusion (200 nM for 28 days) to prevent BDNF production in the substantia nigra of rats mimics many features of the classical animal models of Parkinson's disease. 62% of antisense treated rats rotate (P < or = 0.05) in response to dopaminergic receptor stimulation by apomorphine. 40% of substantia nigra pars compacta tyrosine hydroxylase immunoreactive neurons are lost (P < or = 0.00001) and dopamine uptake site density measured by (3)H-mazindol autoradiography is reduced by 34% (P < or = 0.005). Loss of haematoxylin and eosin stained nigral neurons is significant (P < or = 0.0001) but less extensive (34%). These observations indicate that loss of BDNF expression leads both to down regulation of the dopaminergic phenotype and to dopaminergic neuronal death. Therefore, reduced BDNF mRNA expression in Parkinson's disease substantia nigra may contribute directly to the death of nigral dopaminergic neurons and the development of Parkinson's disease.

Cell Culture Models for Oscillator and Pacemaker Function: Recipes for Dishes with Circadian Clocks?

Primary cell cultures of avian pinealocytes and the mammalian suprachiasmatic nucleus (SCN), immortalized cell lines derived from the SCN (SCN2.2), and fibroblasts derived from mice and rats have been employed as in vitro models to study the cellular and molecular mechanisms underlying circadian biological clocks. This article compares and contrasts these model systems and describes methods for avian pinealocyte cultures, immortalized SCN2.2 cells, and mouse fibroblast culture. Each of these culture models has advantages and disadvantages. Avian pinealocytes are photoreceptive, contain a circadian pacemaker, and produce rhythms of an easily assayed endocrine output-melatonin. However, the molecular mechanisms underlying pinealocyte function are not understood. SCN2.2 cells express metabolic and molecular rhythms and can impose rhythmicity on cocultured cells as well as rat behavior when transplanted into the brain. Yet, the entrainment pathways are not experimentally established in these cells. Fibroblast cultures are simple to produce and express molecular clock gene rhythms, but they express neither physiological rhythmicity nor pacemaker properties. The relative merits of these culture systems, as well as their impact on understanding circadian organization in vivo, are also considered.

Effects of altered Clock gene expression on the pacemaker properties of SCN2.2 cells and oscillatory properties of NIH/3T3 cells

While peripheral tissues and serum-shocked fibroblasts express rhythmic oscillations in clock gene expression, only the suprachiasmatic nucleus (SCN) is capable of endogenous, self-sustained rhythmicity and of functioning as a pacemaker by imposing rhythmic properties upon other cells. To differentially examine the molecular elements necessary for the distinctive rhythm-generating and pacemaking properties of the SCN, the effects of antisense inhibition of Clock expression on the rhythms in 2-deoxyglucose uptake and Per gene expression were compared in immortalized SCN cells and a fibroblast cell line. Similar to changes in molecular and physiological rhythmicity observed in the SCN of Clock mutant mice, the rhythmic pattern of Per2 expression was disrupted and the period of metabolic rhythmicity was increased in SCN2.2 cells subjected to antisense inhibition of Clock. NIH/3T3 fibroblasts cocultured with antisense-treated SCN2.2 cells showed metabolic rhythms with comparable increases in period and decreases in rhythm amplitude. Per2 expression in these cocultured fibroblasts exhibited a similar reduction in peak levels, but was marked by non-24 h or irregular peak-to-peak intervals. In serum-shocked NIH/3T3 fibroblasts, oscillations in Per2, Bmal1, and Cry1 expression persisted with some change in rhythm amplitude during antisense inhibition of CLOCK, demonstrating that feedback interactions between Clock and other core components of the clock mechanism may be regulated differently in SCN2.2 cells and fibroblasts. The present results suggest that CLOCK is differentially involved in the generation of endogenous molecular and metabolic rhythmicity within SCN2.2 cells and in the regulation of their specific outputs that control rhythmic processes in NIH/3T3 cells.

Signalling by the FGFR-like tyrosine kinase, Kringelchen, is essential for bud detachment in Hydra vulgaris

Signalling through fibroblast growth factors (FGFR) is essential for proper morphogenesis in higher evolved triploblastic organisms. By screening for genes induced during morphogenesis in the diploblastic Hydra, we identified a receptor tyrosine kinase (kringelchen) with high similarity to FGFR tyrosine kinases. The gene is dynamically upregulated during budding, the asexual propagation of Hydra. Activation occurs in body regions, in which the intrinsic positional value changes. During tissue displacement in the early bud, kringelchen RNA is transiently present ubiquitously. A few hours later – coincident with the acquisition of organiser properties by the bud tip – a few cells in the apical tip express the gene strongly. About 20 hours after the onset of evagination, expression is switched on in a ring of cells surrounding the bud base, and shortly thereafter vanishes from the apical expression zone. The basal ring persists in the parent during tissue contraction and foot formation in the young polyp, until several hours after bud detachment. Inhibition of bud detachment by head regeneration results in severe distortion, disruption or even complete loss of the well-defined ring-like expression zone. Inhibition of FGFR signalling by SU5402 or, alternatively, inhibition of translation by phosphorothioate antisense oligonucleotides inhibited detachment of buds, indicating that, despite the dynamic expression pattern,the crucial phase for FGFR signalling in Hydra morphogenesis lies in bud detachment. Although Kringelchen groups with the FGFR family, it is not known whether this protein is able to bind FGFs, which have not been isolated from Hydra so far.

Ten years of antisense inhibition of brain G-protein-coupled receptor function

Antisense oligonucleotides (AOs) are widely used as tools for inhibiting gene expression in the mammalian central nervous system. Successful gene suppression has been reported for different targets such as neurotransmitter receptors, neuropeptides, ion channels, trophic factors, cytokines, transporters, and others. This illustrates their potential for studying the expression and function of a wide range of proteins. AOs may even find therapeutic applications and provide an attractive strategy for intervention in diseases of the central nervous system (CNS). However, a lack of effectiveness and/or specificity could be a major drawback for research or clinical applications. Here we provide a critical overview of the literature from the past decade on AOs for the study of G-protein-coupled receptors (GPCRs). The following aspects will be considered: mechanisms by which AOs exert their effects, types of animal model system used, detection of antisense action, effects of AO design and delivery characteristics, non-antisense effects and toxicological properties, controls used in antisense studies to assess specificity, and our results (failures and successes). Although the start codon of the mRNA is the most popular region (46%) to target by AOs, targeting the coding region of GPCRs is almost as common (41%). Moreover, AOs directed to the coding region of the GPCR mRNA induce the highest reductions in receptor levels. To resist degradation by nucleases, the modified phosphorothioate AO (S-AO) is the most widely used and effective oligonucleotide. However, the end-capped phosphorothioate AOs (ECS-AOs) are increasingly used due to possible toxic and non-specific effects of the S-AO. Other parameters affecting the activity of a GPCR-targeting AO are the length (mostly an 18-, 20- or 21-mer) and the GC-content (mostly varying from 30 to 80%). Interestingly, one-third of the AOs successfully targeting GPCRs possess a GC/AT ratio of 61-70%. AO-induced reductions in GPCR expression levels and function range typically from 21 to 40% and 41 to 50%, respectively. In contrast to many antisense reviews, we therefore conclude that the functional activity of a GPCR after AO treatment correlates mostly with the density of the target receptors (maximum factor 2). However, AOs are no simple tools for experimental use in vivo. Despite successful results in GPCR research, no general guidelines exist for designing a GPCR-targeting AO or, in general, for setting up a GPCR antisense experiment. It seems that the correct choice of a GPCR targeting AO can only be ascertained empirically. This disadvantage of antisense approaches results mostly from incomplete knowledge about the internalisation and mechanism of action of AOs. Together with non-specific effects of AOs and the difficulties of assessing target specificity, this makes the use of AOs a complex approach from which conclusions must be drawn with caution. Further antisense research has to be carried out to ensure the adequate use of AOs for studying GPCR function and to develop antisense as a valuable therapeutic modality.

Effects of L-arginine-derived nitric oxide synthesis on cardiovascular responses to stimulus-evoked somatosympathetic reflexes in the gracile nucleus

The purpose of these studies was to determine the role of gracile nucleus (Gr) and the effects of L-arginine-derived nitric oxide (NO) synthesis in the nucleus on the cardiovascular responses to somatosympathetic reflexes (SSR). Electrical stimulation of sural and tibial nerve to evoke excitatory and inhibitory SSR was carried out in anesthetized Sprague-Dawley rats. Arterial blood pressure and heart rate were monitored during stimulus-evoked SSR following microinjections of the agents into Gr. Cardiovascular responses to electrical stimulation of the sural and tibial nerves were blocked by microinjection of lidocaine into Gr. The hypertensive and tachycardiac responses to stimulation of the sural nerve were attenuated by bilateral microinjection of L-arginine into Gr, but enhanced by the presence of nNOS antisense oligodeoxynucleotides (oligos) in the area. Microinjection of L-arginine into Gr facilitated the hypotensive and bradycardic responses to stimulation of the tibial nerve while pretreatment with nNOS antisense oligos into Gr attenuated the tibial stimulation evoked inhibitory SSR. The stimulus-evoked responses were not altered by microinjection of nNOS sense oligos into Gr. The results show that the cardiovascular responses to stimulus-evoked SSR were inhibited by the presence of a blockade of neuronal conduction in the Gr. L-Arginine-derived NO synthesis in the Gr attenuates the cardiovascular responses to stimulus-evoked excitatory SSR and facilitates the responses to inhibitory SSR. We conclude that NO in the Gr plays an inhibitory role in the central cardiovascular control through SSR regulation.

GeneBlocs are powerful tools to study and delineate signal transduction processes that regulate cell growth and transformation

The study of signal transduction processes using antisense oligonucleotides is often complicated by low intracellular stability of the antisense reagents or by nonspecific effects that cause toxicity. Here, we introduce a new class of antisense molecules, so-called GeneBlocs, which are characterized by improved stability, high target RNA specificity, and low toxicity. GeneBlocs allow for efficient downregulation of mRNA expression at nanomolar concentrations, and they do not interfere with cell proliferation. We demonstrate these beneficial properties using a positive readout system. GeneBloc-mediated inhibition of tumor suppressor PTEN (phosphatase and tension homologue detected on chromosome 10) expression leads to hyperactivation of the phosphatidylinositol (PI) 3-kinase pathway, thereby mimicking the loss of PTEN function and its early consequences observed in mammalian cancer cells. Specifically, cells treated with PTEN GeneBlocs show functional activation of Akt, a downstream effector of PI 3-kinase signaling, and exhibit enhanced proliferation when seeded on a basement membrane matrix. In addition, GeneBlocs targeting the catalytic subunit of PI 3-kinase, p110, specifically inhibit signal transduction of endogenous or recombinant PI 3-kinase. This demonstrates that GeneBlocs are powerful tools to analyze and to modulate signal transduction processes and, therefore, represent alternative reagents for the validation of gene function.

The bone morphogenetic protein antagonist Noggin is regulated by Sox9 during endochondral differentiation

Noggin has been described to be capable of binding bone morphogenetic proteins (BMP) and inhibiting BMP signaling by preventing the interactions of BMP with their receptors. Noggin expression during endochondral differentiation was analyzed to elucidate its potential role during chondrogenesis. Throughout mouse development, Noggin was expressed abundantly in the chondrocytic lineage as early as collagen type II RNA was detectable. In addition, a strong correlation was detected between Noggin expression and the expression profile of Sox9 during chondrogenesis. Sox9 (known to play an important role during chondrogenesis) and Noggin expression were investigated in the pluripotent mesenchymal cell line C3H10T1/2, stimulated by BMP-2. BMP-2 caused significant upregulation of Sox9 and Noggin expression in these cells. The upregulation of Noggin could be inhibited by introducing antisense oligonucleotides against Sox9 mRNA into the cells. Using mouse limb bud cultures, the role of Sox9 and Noggin during endochondral tissue differentiation was further studied. Treatment of cultures with Sox9 antisense oligonucleotides and/or Noggin protein caused significant alterations in limb morphogenesis and endochondral development. The data suggest that the transcriptional control of Noggin by Sox9 is a potent regulatory mechanism in chondrocyte differentiation.

The use of synthetic polymers for delivery of therapeutic antisense oligodeoxynucleotides

Developed over the past two decades, the antisense strategy has become a technology of recognised therapeutic potential, and many of the problems raised earlier in its application have been solved to varying extents. However, the adequate delivery of antisense oligodeoxynucleotides to individual cells remains an important and inordinately difficult challenge. Synthetic polymers appeared on this scene in the middle 1980s, and there is a surprisingly large variety used or proposed so far as agents for delivery of oligodeoxynucleotides. After discussing the principles of antisense strategy, certain aspects of the ingestion of macromolecules by cells, and the present situation of delivery procedures, this article analyses in detail the attempts to use synthetic polymers as carrier matrices and or cell membrane permeabilisation agents for delivery of antisense oligodeoxynucleotides. Structural aspects of various polymers, as well as the results, promises and limitations of their use are critically evaluated.

Requirement of protein tyrosine phosphatase SHP2 for NO-stimulated vascular smooth muscle cell motility

We have previously reported that nitric oxide (NO) increases the motility of differentiated cultured primary aortic smooth muscle cells from adult rats. There is little information on the role of protein tyrosine phosphatases in vascular biology. One such phosphatase, Src homology 2 phosphatase 2 (SHP2), is essential for motility. We tested the hypothesis that NO increases SHP2 levels via a cGMP-mediated mechanism and that this effect is necessary for NO-stimulated cell motility. Here we report that two different NO donors increased SHP2 protein levels and enzyme activity. This effect was mimicked by several cGMP agonists and blocked by an inhibitor of guanylyl cyclase. Specific decrease of SHP2 protein levels via the use of antisense oligodeoxynucleotides (ODNs), but not several control ODNs attenuated the motogenic effect of NO, which indicates the involvement of SHP2 in NO-elicited motogenesis. S-nitroso-N-acetylpenicillamine failed to increase SHP2 protein levels in subcultured aortic smooth muscle cells. This provides a potential explanation for the lack of effect of NO on cell motility in dedifferentiated subcultured cells. These results support the hypothesis that NO-elicited upregulation of SHP2 via a cGMP-mediated pathway is necessary for NO-induced motogenesis in differentiated aortic smooth muscle cells.

The involvement of a stress-activated pathway in equine influenza virus-mediated apoptosis

We have shown elsewhere that equine-2 influenza virus (EIV; subtype H3N8) induced pronounced cell death in infected cells through apoptosis as demonstrated by DNA fragmentation assay and a combined TUNEL and immunostaining scheme. In this study, we investigated the mechanism of EIV-mediated cytotoxicity on a permissive mammalian epithelial cell line, Madin-Darby canine kidney (MDCK) cells. EIV infection increased the cellular levels of oxidative stress and c-Jun/AP-1 protein (which is known to be affected by oxidative stress), as well as its DNA binding activity. Increased production of TGF-beta1, an inducer of c-Jun N-terminal kinase or stress-activated protein kinase (JNK/SAPK) activation, was also detected in EIV-infected MDCK cells. It has been reported that TGF-beta may initiate a signaling cascade leading to JNK/SAPK activation. Addition of c-Jun antisense oligodeoxynucleotide, antioxidant N-acetyl-cysteine (NAC), JNK/SAPK inhibitor carvedilol, or TGF-beta-neutralizing antibody effectively blocked c-Jun/AP-1 upregulation and TGF-beta1 production mediated by EIV infection. These treatments also attenuated EIV-induced cytopathogenic effects (CPE) and apoptosis. Our results suggest that a stress-activated pathway is involved in apoptosis mediated by EIV infection. It is likely that EIV infection turns on the JNK/SAPK cascade, which modulates the activity of apoptosis-promoting regulatory factor c-Jun/AP-1 and epithelial growth inhibitory cytokine TGF-beta.

Prostaglandin receptor subtypes, EP3C and EP4, mediate the prostaglandin E2-induced cAMP production and sensitization of sensory neurons

Although a number of prostaglandin E(2) (PGE(2)) receptor subtypes have been cloned, limited studies have been performed to elucidate subtypes that subserve specific actions of this eicosanoid, in part because of a paucity of selective receptor antagonists. Using reverse transcription-polymerase chain reaction (PCR) and antisense oligonucleotides, we examined which prostaglandin E(2) receptor (EP receptor) subtypes are expressed in sensory neurons and which mediate the PGE(2)-induced increase in cAMP production and augmentation of peptide release. Reverse transcription-PCR of cDNA isolated from rat sensory neurons grown in culture revealed PCR products for the EP1, EP2, EP3C, and EP4 receptor subtypes but not the EP3A or EP3B. Preexposing neuronal cultures for 48 h to antisense oligonucleotides of EP3C and EP4 mRNA diminished expression of the respective receptors by approximately 80%, abolished the PGE(2)-stimulated production of cAMP, and blocked the ability of PGE(2) to augment release of immunoreactive substance P and calcitonin gene-related peptide. Pretreating with individual antisense against the EP2, EP3C, or EP4 receptors or combinations of missense oligonucleotides had no effect on PGE(2)-induced activity. Treatment with antisense to EP3C and EP4 receptor subtypes did not alter the ability of forskolin to increase cAMP or enhance peptide release. These results demonstrate that sensory neurons are capable of expressing multiple EP receptor subtypes but that only the EP3C and EP4 receptors mediate PGE(2)-induced sensitization of sensory neurons.

Investigating the mechanisms of retinal degenerations with antisense oligonucleotides

Utilizing antisense oligonucleotides coupled with an intact Xenopus eye rudiment model, we have effectively demonstrated that we are able to downregulate the expression of a photoreceptor-specific protein, rds/peripherin, and generate a loss-of-function model upon which to further study the function of the rds/peripherin gene. The ultrastructure and protein expression patterns very closely resemble those previously documented in both the rds mouse and in human autosomal dominant retinitis pigmentosa due to peripherin/RDS mutations. An identical strategy can be applied to any gene correlated with a degenerative retinal phenotype. As the entire array of genes is revealed through the various genome projects, including human and mouse, it is becoming increasingly critical to evaluate and determine the function of the corresponding gene products. Discovering which gene is responsible for a particular clinical phenotype is only the first of many steps in the development of a treatment or cure for that particular disease. Using our in vitro model, in which the retina is readily accessible to the antisense oligonucleotide yet the normal three-dimensional ultrastructure of the retina is maintained, we can evaluate the function of virtually any gene as the sequence becomes available. A thorough understanding of the function of individual genes will provide insights on the role of gene product in retinal health and pathophysiology. This experimental approach will also allow for specific therapeutic interventions to be evaluated so that targeted treatments can be designed for individuals with specific genetic mutations.

Intrathecal administration of PNA targeting galanin receptor reduces galanin-mediated inhibitory effect in the rat spinal cord

Peptide nucleic acids (PNA) are nucleic acid analogues containing neutral amide backbone, forming stable and tight complexes with complementary DNA/RNA. However, it is unclear whether unmodified PNA can efficiently penetrate neuronal tissue in order to act as antisense reagent. Here we show that intrathecal (i.t.) injection of an unmodified antisense PNA complementary to the rat galanin receptor type 1 (GalR1) mRNA is able to block the inhibitory effect of i.t. administered galanin on spinal nociceptive transmission. Autoradiographic ligand binding studies using [125I]galanin show that the unmodified PNA is able to reduce the density of galanin binding sites in the dorsal horn. Thus, unmodified PNA applied i.t. appears to function as an effective antisense reagent in rat spinal cord in vivo.

Effects of oligonucleotide antisense to dopamine D(1A) receptor messenger RNA in a rodent model of levodopa-induced dyskinesia

Dyskinesias are abnormal involuntary movements which develop as a side-effect of long-term treatment with levodopa in patients with Parkinson's disease. The pathophysiology underlying these dyskinesias remains unclear, although, it has been suggested that heightened activity of dopamine D(1) receptor-bearing striatonigral neurons may play a key role. Chronic pulsatile levodopa administration to hemiparkinsonian rats results in sensitization of rotational responses to apomorphine. This sensitization is thought to be analogous to levodopa-induced dyskinesias in humans. In these studies, we further clarify the role of the dopamine D(1A) receptor in this rodent model of levodopa-induced dyskinesias using an in vivo oligonucleotide antisense approach. Hemiparkinsonian rats received twice daily injections of levodopa for three weeks followed by intrastriatal infusion of dopamine D(1A) receptor antisense (7nmol/day, three days), a scrambled missense control sequence, or saline. Those animals treated with antisense displayed significantly fewer apomorphine-induced rotations than saline- or missense-treated controls.By reducing dopamine D(1A) receptor expression, we were able to attenuate sensitization of the response to apomorphine resulting from chronic pulsatile levodopa treatment. Thus, the dopamine D(1A) receptor appears to play a significant role in levodopa-induced dyskinesias and warrants further examination. These findings may have important implications for the development of selective treatment strategies designed to alleviate parkinsonian symptoms, while minimizing motor complications.

Gene interference using antisense oligodeoxynucleotides on whole chick embryos. Optimal ring and roller-bottle culture technique

Details are given of an advanced version of the ring method of chick embryo culture. This ensures good development from early blastoderm stages even when the culturing procedure is interrupted by the extended periods required for collecting matched embryo samples and for preparing antisense treatment. Antisense oligodeoxynucleotide treatment, in short-term incubation before return of blastoderms to their ring cultures, is then described. An alternative, roller-bottle, culture method for continued development after treatment is also described. Criteria for the validity and success of this gene interference method are given. While the text is meant to be of detailed practical help to those inexperienced in embryo culture, a preliminary reading, and familiarity with its sectional (Subheading) structure, is recommended before work is undertaken.

Antisense oligonucleotide blockade of connexin expression during embryonic bone formation: evidence of functional compensation within a multigene family

Prior studies in our laboratory demonstrated the presence of gap junction proteins (connexins) throughout intramembranous bone formation [Minkoff et al. (1994) Anat Embryol 190:231-241]. In addition, two members of the connexin family of gap junction proteins, connexin 43 (Cx43; Gj alpha 1) and connexin 45 (Cx45; Gj alpha 6), were found by Civitelli et al. [1993; J Clin Invest 91:1888-1896] to be associated, specifically, with osteogenesis. Recently, however, a null mutation in the gene encoding Gj alpha 1 in mice has been produced by Reaume et al. [1995; Science 267:1831-1834]. Gj alpha 1 null homozygotes survived to term but died at birth of heart abnormalities. Examination of the null homozygous embryos, surprisingly, did not reveal overt histological or anatomical abnormalities in any organ system other than the heart. In view of this, the present investigation was initiated in order to evaluate bone formation under conditions in which the expression of Gj alpha 1 and Gj alpha 6, the connexins specifically associated with osteogenesis, had been perturbed, individually as well as in combination. An in vitro system employing organ cultures of dissociated embryonic chick mandibular mesenchyme was employed. Mesenchyme was cultured in the presence and absence of sense and antisense oligodeoxynucleotides (ODN), ranging in length from 15 to 24 mer and containing sequences that included the initiation codon of Gj alpha 1 and of Gj alpha 6. In cultures of mesenchyme, grown for 6 to 13 days in the presence of the combined antisense ODNs to Gj alpha 1 and Gj alpha 6, bone formation was markedly reduced or absent. By contrast, in cultures grown in medium containing the combination of corresponding sense ODNs to both Gj alpha 1 and Gj alpha 6, bone formation was evident. In addition, when cultures were grown in the presence of antisense or sense ODNs to either Gj alpha 1 or Gj alpha 6, individually, bone formation was seen. Immunohistochemical analysis of connexin expression revealed intense immunoreactive signal to Gj alpha 1 and Gj alpha 6 in bone of the control explants, in which no ODNs were present; in those cultures in which either Gj alpha 1 and Gj alpha 6 antisense ODNs were present, however, the expression of the respective connexin protein was either significantly reduced or absent. Further, in those explants in which Gj alpha 1 expression was blocked, immunoreactive signal to Gj alpha 6 appeared to have been amplified in regions of developing bone. These results suggest that, in avian osteogenic tissue, when Gj alpha 1 protein expression has been impeded another related connexin protein (Gj alpha 6) may subserve the functions of the missing connexin. The findings of this study, therefore, support the hypothesis that, within the connexin gene family, functional compensation can occur.

The transcription factor Sox9 is involved in BMP-2 signaling

We investigated the regulation of Sox9, a transcription factor known to play a role in chondrogenesis, by bone morphogenetic protein-2 (BMP-2) and hedgehog proteins in order to better understand their signaling function in endochondral bone formation. The mesenchymal progenitor cell line C3H10T1/2 was stimulated with BMP-2. Sox9 expression levels were measured by quantitative reverse transcriptase-polymerase chain reaction and Northern analysis. We found that Sox9 was up-regulated by BMP-2 in a dose-dependent manner. The expression of Col2a1, a downstream response gene of Sox9, was also significantly increased upon BMP-2 addition. We also monitored Sox9 expression after the addition of BMP-2 to osteosarcoma cell lines; BMP-2 treatment increased Sox9 mRNA levels in MG63, considered to be early osteoblast-like, but not in human osteogenic sarcoma (HOS) cells, which are thought to be more advanced in the osteoblastic lineage. This response seems to be influenced by differences in BMP receptor expression; MG63 cells express BMP receptor IA (BMPR-IA), whereas HOS cells express BMPR-IA and BMPR-IB. We also saw an increase in Sox9 mRNA levels in BMP-2-treated primary human bone cells (HBCs) derived from femoral heads. We found that in addition to BMP-2, Sonic and Indian hedgehog can increase Sox9 expression in C3H10T1/2 and primary HBCs. Time course studies with C3H10T1/2 cells after BMP-2 stimulation showed increasing expression of cartilage markers, decrease of collagen I mRNA, and a late induction of osteocalcin expression. Moreover, the treatment of C3H10T1/2 cells with Sox9 antisense oligonucleotides revealed that Sox9 is a downstream mediator of BMP-2 affecting the expression of chondrocyte and osteoblast marker genes. Our data show that Sox9 is an important downstream mediator of the BMP-2 and hedgehog signaling pathways in osteogenic cells.

Role of PTP-1B in aortic smooth muscle cell motility and tyrosine phosphorylation of focal adhesion proteins

Recent studies have focused attention on the role of protein tyrosine kinases in vascular smooth muscle cell biology, but similar information regarding protein tyrosine phosphatases (PTP) is sparse. PTP-1B is a ubiquitous nonreceptor phosphatase with uncertain function and substrates that are mostly unidentified. We used antisense oligodeoxynucleotides (ODN) against PTP-1B to investigate the role of endogenous PTP-1B in motility of primary cultures of rat aortic smooth muscle cells (RASMC). Antisense ODN decreased PTP-1B protein levels and activity in a concentration-dependent fashion, whereas sense, scrambled, or three-base mismatch antisense ODN had little or no effect. Treatment of cells with antisense ODN, but not sense, scrambled, or three-base mismatch antisense ODN, enhanced cell motility and increased tyrosine phosphorylation levels of focal adhesion proteins paxillin, p130(cas), and focal adhesion kinase. Our findings indicate that PTP-1B is a negative regulator of RASMC motility via modulation of phosphotyrosine levels in several focal adhesion proteins and suggest the involvement of PTP-1B in events such as atherosclerosis and restenosis, which are associated with increased vascular smooth muscle cell motility.

Intra-accumbens infusions of antisense oligodeoxynucleotides to one isoform of glutamic acid decarboxylase mRNA, GAD65, but not to GAD67 mRNA, impairs sustained attention performance in the rat

The effects of bilateral infusions of antisense oligodeoxynucleotides (ODNs) for the two isoforms of glutamic acid decarboxylase (GAD65; GAD67) into the nucleus accumbens on the performance of intact rats in a task designed to assess sustained attention were tested. The task required the animals to discriminate between signal and non-signal events. Signals and non-signals were presented randomly and unpredictably. The task generated all four response types of a sustained attention task, i.e., hits, misses, correct rejections, false alarms. Infusions of the scrambled sequence ODNs did not affect performance. Likewise, infusions of the GAD67 ODNs failed to produce any effect. However, infusions of the GAD65 ODNs into the nucleus accumbens resulted in a robust and reliable decrease in the relative number of hits. Similarly, the combined infusion of GAD65+67 ODNs impaired the hit rate but did not affect the animals' ability to reject non-signals. Following each treatment series, performance rapidly returned to baseline, further indicating the specificity and reversibility of the effects of the infusions of the ODNs. While these data suggest that translation arrest of specifically the GAD65 isoform of the enzyme in the nucleus accumbens impairs attentional performance, the neuronal mechanisms mediating these effects remain unsettled.

Intrastriatal and intraventricular injections of oligodeoxynucleotides in the rat brain: tissue penetration, intracellular distribution and c-fos antisense effects

We have determined the time course, the spatial spread in brain tissue, and the intracellular distribution of biotin- and fluorescein-labeled phosphorothioate oligodeoxynucleotides (ODNs) following single injections into the rat striatum or the lateral ventricle. These time and space parameters were correlated with the ability of c-fos phosphorothioate antisense ODNs to suppress the induction of Fos protein by cocaine. A rapid and dose-dependent tissue penetration of labeled ODNs was observed following either intrastriatal or intraventricular injections of a constant sample volume. Inspection of tissue sections by confocal microscopy uncovered a distinct change in the intracellular disposition of labeled ODNs during the 24 h post-injection period. At 1, 6 and 12 h, the vast majority of the fluorescent signal was confined to the interstitial spaces throughout the zone penetrated by ODNs. Neuronal nuclei displayed faint labeling along the outer portion of the nucleus at 1 and 6 h post-injection. At these time-points, ODNs were not detected in the cytoplasm. By 16 h, ODNs were barely detectable in the extracellular space and absent from neuronal nuclei. Instead, ODNs were seen in large cytoplasmic granules of neurons throughout the tissue zone penetrated by the ODNs. Experiments with intrastriatal injections of antisense ODNs to c-fos mRNA revealed Fos suppression between 3 and 12 h, but not at 16 and 24 h. This combined analysis has revealed that (1) restricted tissue penetration by ODNs limits their antisense effects on protein expression, and (2) depletion of extracellular ODNs and sequestration of c-fos antisense ODNs into large intracellular granules coincides with the loss of their biological activity.

Intra-amygdala infusion of an end-capped antisense oligodeoxynucleotide to c-fos accelerates amygdala kindling

The changes produced by repeated stimulation of the brain that result in the kindling effect remain unknown. It is known, however, that activation of immediate early genes including c-fos is a very early event in the development of kindling. Here we show that c-fos expression in the amygdala can be knocked-down by an end-capped antisense oligodeoxynucleotide (but not by vehicle, or control antisense oligodeoxynucleotides) and that this results in an acceleration of kindling. These results suggest that, at least in the amygdala, the expression of c-fos is associated with an attempt by the brain to retard the development of kindling.

Chemokine inhibition in rat stab wound brain injury using antisense oligodeoxynucleotides

Traumatic injury to the central nervous system (CNS) results in the breakdown of the blood-brain barrier and recruitment of hematogenous cells at the site of injury. The role of chemokines in this process has been well recognized and they have been regarded as promising targets for development of anti-inflammatory therapies. The expression of monocyte chemoattractant protein (MCP-1), in particular, has been closely linked to macrophage infiltration following trauma in rat brain. In this study we determined whether inhibition of MCP-1 following stab wound injury would reduce macrophage infiltration. Stab wound injured Sprague-Dawley rats were infused with MCP-1 sense or antisense oligonucleotides using an Alzet miniosmotic pump (1 microl/h for 3 days). Three days following injury, widespread gliosis was observed in both groups of rats as judged by glial fibrillary acidic protein (GFAP) immunoreactivity. Immunohistochemistry showed significantly less staining for MCP-1 in antisense treated animals. In addition, the number of macrophages were reduced by 30% in the antisense compared to the sense treated animals (P < 0.05). These results demonstrate that modulation of MCP-1 expression in stab wound injury directly affects monocytic infiltration and provide a basis for MCP-1 inhibition as a therapeutic strategy for controlling inflammatory events of traumatic brain injury.

Antisense Oligodeoxynucleotide Technology: Potential Use for the Treatment of Malignant Brain Tumors

BACKGROUND: Antisense oligodeoxynucleotides (ODNs) have been proposed as a new therapy for patients with cancer, including malignant brain tumors. Antisense ODNs are taken up by tumor cells and selectively block gene expression. Use of ODNs for brain tumors is attractive due to their theoretical specificity, relative ease of production and, to date, paucity of reported adverse effects. This article presents current information regarding antisense ODNs and their possible future use for the treatment of brain tumors. METHODS: The available published experimental and clinical information regarding antisense ODN treatment of glioblastoma cells and administration into the central nervous system (CNS) was reviewed. Other clinically relevant information pertaining to the molecular biology of antisense ODNs was also collected and summarized. RESULTS: Targets for antisense ODN therapy in malignant glioma cells have included c-myc, c-myb, c-sis, c-erb B, CD44, p34cdc2, bFGF, PDGF, TGF-beta, IGF-1, PKC-alpha tumor necrosis factor, urokinase, and S100beta protein. Few in vivo studies of ODN treatment of brain tumors have yet been reported. Systemically administered ODNs enter the brain only in extremely small quantities; therefore, microinfusion into the brain has been recommended. CONCLUSIONS: Antisense ODNs have been used successfully to block glioblastoma gene expression in vitro and expression of multiple genes within the CNS of experimental animals. Upcoming clinical trials will address the safety of antisense ODN use against malignant brain tumors.

Intracerebroventricular administration of antisense oligodeoxynucleotide against GLUT2 glucose transporter mRNA reduces food intake, body weight change and glucoprivic feeding response in rats

The GLUT2 glucose transporter, which may play a glucose-sensing role in hepatocyte and islet beta cells because of its low affinity and high Km for glucose, has been identified in some discrete brain areas that are related to feeding behavior and energy metabolism. We tested the hypothesis that brain GLUT2 may play a role in the control of food intake by antisense technology loss-of-function analysis. Antisense oligonucleotides directed against GLUT2 mRNA were administered intracerebroventricularly to eight rats daily for 13 days. Another eight rats were administered intracerebroventricularly with missense oligonucleotides as the control. Food intake was monitored by a computerized feeding system. Data were analyzed using a one-way general linear model or Mann-Whitney U test when appropriate. Cumulative food intake and body weight change in antisense-treated rats were significantly lower (18 and 160%, respectively) in the group treated with antisense oligonucleotides than in the group treated with missense control oligonucleotides. There was no increase in cumulative food intake in response to 2-deoxyglucose challenge in rats treated with antisense oligonucleotide, but in those treated with missense control oligonucleotide, cumulative food intake was fivefold greater in response to 2-deoxyglucose. These data suggest a possible role of brain GLUT2 in the regulation of food intake and body energy stores.

Antisense oligonucleotides in psychopharmacology and behaviour: promises and pitfalls

Antisense oligonucleotides are used to study the expression and function of a diverse range of proteins. Areas for which antisense has been used for pharmacological investigation include receptors, neuropeptides and immediate early genes, particularly when specific ligands or markers are not yet available. Antisense oligonucleotides target a specific mRNA and block the expression of the protein by sequence specific hybridization. This technique has not only been shown to be a valuable pharmacological tool but also to have potential therapeutic applications. In this review we discuss the technology behind the technique including developments in methodology employed in antisense experiments. Although antisense provides a novel and highly specific tool, the reliability of the technique and many of the problems associated with antisense experiments are discussed. The main focus of this article is the use of antisense in psychopharmacology to investigate behavioural changes following antisense-mediated inhibition of the expression of specific brain proteins and receptors.

Putative roles for the inducible transcription factor c-fos in the central nervous system: studies with antisense oligonucleotides

Although immediate-early genes such as c-fos are widely believed to play an important role in neuroplasticity, there is limited evidence to support involvement in the initiation of molecular events leading to medium- and long-term changes in brain function following a stimulus. Results using techniques such as transgenic knockout of the gene are often difficult to interpret. Antisense oligonucleotide technology offers an alternative. Infusion of antisense oligonucleotide to modify the expression of c-fos in the brain results in dramatic changes in rotation behaviour in animals challenged with psychostimulant drugs such as amphetamine. Similarly, the knockdown of c-fos expression using antisense oligonucleotides can also alter the rate of amygdala kindling in response to electrical stimulation of the brain. While studies using antisense oligonucleotides to knockdown c-fos expression provide evidence that the expression of c-fos plays an important role in regulating neuronal function, the use of antisense nucleotides has limitations and experiments must be very carefully controlled. Many details of antisense oligonucleotide actions remain unknown.

Inhibition of the p50 (NKkappaB1) subunit of NF-kappaB by phosphorothioate-modified antisense oligodeoxynucleotides reduces NF-kappaB expression and immunoglobulin synthesis in murine B cells

NF-kappaB is a regulatory protein of immune response genes and a candidate for targeting in immunosuppressive therapy. NF-kappaB proteins are formed from components of which p50 (NFkappaB1) is a subunit. By targeting p50 gene expression with specific antisense 3' phosphorothioate-oligodeoxynucleotides (3' PS-ODNs), an effect upon NF-kappaB regulation and immunoglobulin synthesis in murine B cells was achieved. A 49% decrease in p50 protein was induced by treatment of WEHI 231 B cells with p50 antisense 3' PS-ODNs and not by control 3' PS-ODNs. p50 antisense specifically reduced the expression of NF-kappaB by 51%, but not the transcription factor, Oct-1. In the BXSB murine model of autoimmunity, p50 antisense inhibited NF-kappaB expression and total IgM and IgG synthesis, but, more importantly, dsDNA antibodies were reduced 90%. These results validate the use of p50 antisense to reduce NF-kappaB expression and, by downregulating the immune response, has application in the treatment of autoimmune disorders.

Strategy for designing specific antisense oligonucleotide sequences

Antisense compounds, various forms of nucleotides or their analogs, inhibit gene function both in vitro and in vivo. Although antisense compounds have been used extensively not only as a basic research tool but also as therapeutics for various diseases, one of the major problems is the difficulty of obtaining optimal sequences to inhibit specific gene functions. Although the terms "sequence-specificity" or "sequence-nonspecificity" are often used, there is no consensus as to how to define and quantitate such sequence specificity. In this review, we introduced hybridization simulation for designing optimal antisense sequences. Each candidate antisense oligonucleotide is assessed by calculating its hybridization energy against potential hybridization sites within the specified database (including GenBank) using a realistic nearest-neighbor thermodynamic model, taking into account mismatches. The specificity of each oligonucleotide is then quantitated by the number of potential cross-hybridizable genes and their degree of cross-hybridization. Furthermore, if antisense sequences exhibit a high potential for hairpin formation, they are not recommended even if they are highly specific. Therefore, to select antisense sequences, one should calculate all the potential factors for each candidate oligonucleotide such as length, location, specificity, hairpin potential, mRNA secondary structure, and dimer formation.

Sensory regulation of immediate-early gene expression in mammalian visual cortex: implications for functional mapping and neural plasticity

The expression of immediate-early genes that code for transcription factors has been extensively studied in the brain with regard to imaging functional activity. The components of the AP-1 transcription factor--in particular, c-Fos--and Zif268 have been widely used for this purpose. However, the precise details by which they are induced after synaptic stimulation remain unknown. Furthermore, the roles of these two proteins in neurons remains speculative and include such varied functions as short-term maintenance of cellular homeostasis to long-term changes that guide cortical plasticity. Current efforts at elucidating the physiological roles of AP-1 and Zif268 rely on assessing their expression in response to different conditions of sensory and pharmacological stimulation. In this review, we have examined the expression patterns of these transcription factors in the mammalian visual cortex under different conditions, with particular emphasis on the constitutive levels and how they change after visual deprivation and stimulation. A synthesis of this information offers further insight into their likely functions and the extent to which transcription factors may represent patterns of neural activity as a possible prelude to plastic events.

Antisense gene therapy for neurodegenerative disease?

Diseases resulting from defects in a single gene may be more amenable to treatment by conventional gene therapy strategies than idiopathic or polygenic disorders. We have attempted to reduce the expression in vivo of the Huntington's disease gene protein, Huntingtin, using an 18-mer fluorescein-labeled phosphorothiorated antisense oligodeoxynucleotide (ODN) targeted against the start site of the first exon of the IT15 gene. Animals were given repeated intrastriatal infusions (5 microliters of a 100 nmol/microliter solution daily over 4 days) of the antisense ODN. The treatments ended on Day 5 and the tissue was processed for immunohistochemical and Western blot analysis. The fluorescein-labeled ODN appeared to penetrate several cells and did not cause any obvious toxicity to the neurons. The average reduction in levels of Huntingtin (16.9 +/- 7.2%) did not differ significantly between striatal tissue of antisense ODN-treated animals compared to those treated with a sense ODN or vehicle. Improved methods for molecular modifications of the IT15 gene may be needed for therapeutic initiatives.

Sequence-independent effects of phosphorothiolated oligonucleotides on synaptic transmission and excitability in the hippocampus in vivo

Antisense oligodeoxynucleotides (ODNs) have the potential to be a powerful tool for regulating gene expression and mRNA translation in spatially and temporally restricted domains. Prior to investigating the effects of antisense ODNs on hippocampal long-term potentiation, we investigated whether there are any non-specific effects of ODNs on perforant path synaptic transmission in the dentate gyrus of both pentobarbital-anaesthetized and awake, freely moving rats. Single injections of phosphorothioated antisense ODNs (4 nmol) to the immediate early gene zif/268 caused a rapid (within minutes) and long-lasting (>24 hr) profound depression of the perforant path evoked field potentials. This depressive effect was due to the phosphorothioate modification since a depression was not seen with unmodified antisense ODNs, relative to saline controls. Furthermore, the effect was not sequence-specific since modified sense ODNs caused the same degree of depression. The depression caused by the modified antisense ODNs was dose-dependent and specific to synaptic transmission, since antidromic population spikes elicited by mossy fibre stimulation were relatively unaffected compared to the orthodromic responses. A second unexpected side-effect of the modified ODNs was cellular hyperexcitability, such that bursts of epileptiform spikes in the EEG occurred both spontaneously and as a result of synaptic stimulation. While the mechanism of the synaptic depression remains unknown, these results indicate that phosphorothioate-modified ODNs exert profound non-specific effects on synaptic transmission in the hippocampus, that have the potential to seriously compromise any corresponding behavioural or electrophysiological studies.

Antisense oligonucleotide to c-fos blocks the ability of arginine vasopressin to maintain ethanol tolerance

Administration of the neuropeptide, arginine vasopressin, can reduce the rate of dissipation of functional ethanol tolerance in mice that have acquired that tolerance. We previously showed that intracerebroventricular vasopressin administration can also produce an increase in septal c-fos mRNA levels. To evaluate the role of the increased expression of c-fos in the ability of vasopressin to maintain tolerance, ethanol-tolerant mice were given intracerebroventricular injections of vasopressin in the presence or absence of an antisense oligonucleotide to c-fos. The antisense oligonucleotide completely blocked the ability of vasopressin to maintain ethanol tolerance, while a missense oligonucleotide was without effect. The antisense oligonucleotide also attenuated the increase in septal c-fos mRNA levels caused by vasopressin. The results provide evidence for a role of c-fos expression in the maintenance of ethanol tolerance by vasopressin.