A dual role of lysophosphatidic acid type 2 receptor (LPAR2) in nonsteroidal anti-inflammatory drug-induced mouse enteropathy.

Lysophosphatidic acid (LPA) is a bioactive phospholipid mediator that has been found to ameliorate nonsteroidal anti-inflammatory drug (NSAID)-induced gastric injury by acting on lysophosphatidic acid type 2 receptor (LPAR2). In this study, we investigated whether LPAR2 signaling was implicated in the development of NSAID-induced small intestinal injury (enteropathy), another major complication of NSAID use. Wild-type (WT) and Lpar2 deficient (Lpar2-/-) mice were treated with a single, large dose (20 or 30 mg/kg, i.g.) of indomethacin (IND). The mice were euthanized at 6 or 24 h after IND treatment. We showed that IND-induced mucosal enteropathy and neutrophil recruitment occurred much earlier (at 6 h after IND treatment) in Lpar2-/- mice compared to WT mice, but the tissue levels of inflammatory mediators (IL-1ß, TNF-α, inducible COX-2, CAMP) remained at much lower levels. Administration of a selective LPAR2 agonist DBIBB (1, 10 mg/kg, i.g., twice at 24 h and 30 min before IND treatment) dose-dependently reduced mucosal injury and neutrophil activation in enteropathy, but it also enhanced IND-induced elevation of several proinflammatory chemokines and cytokines. By assessing caspase-3 activation, we found significantly increased intestinal apoptosis in IND-treated Lpar2-/- mice, but it was attenuated after DBIBB administration, especially in non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice. Finally, we showed that IND treatment reduced the plasma activity and expression of autotaxin (ATX), the main LPA-producing enzyme, and also reduced the intestinal expression of Lpar2 mRNA, which preceded the development of mucosal damage. We conclude that LPAR2 has a dual role in NSAID enteropathy, as it contributes to the maintenance of mucosal integrity after NSAID exposure, but also orchestrates the inflammatory responses associated with ulceration. Our study suggests that IND-induced inhibition of the ATX-LPAR2 axis is an early event in the pathogenesis of enteropathy.

Germline MUTYH mutations and high-grade gliomas: Novel evidence for a potential association.

There is growing body of evidence supporting the role of germline mutations in the pathogenesis of pediatric central nervous system (CNS) tumors, and the widespread use of next-generation sequencing (NGS) panels facilitates their detection. Variants of the MUTYH gene are increasingly recognized as suspected germline background of various extraintestinal malignancies, besides their well-characterized role in the polyposis syndrome associated with biallelic mutations. Using a multigene NGS panel (Illumina TruSight Oncology 500), we detected one H3 G34V- and one H3 K27M-mutant pediatric high-grade diffuse glioma, in association with c.1178G>A (p.G393D) and c.916C>T (p.R306C) MUTYH variants, respectively. Both MUTYH mutations were germline, heterozygous and inherited, according to the subsequent genetic testing of the patients and their first-degree relatives. In the H3 K27M-mutant glioma, amplifications affecting the 4q12 region were also detected, in association with KDR-PDGFRA, KIT-PDGFRA, and KDR-CHIC2 fusions, previously unreported in this entity. Among 47 other CNS tumors of various histological types tested with the same NGS panel in our institution, only one adult glioblastoma harbored MUTYH mutation. Together with a single previous report, our data raises the possibility of an association between germline MUTYH mutations and CNS malignancies, particularly in pediatric histone H3-mutant gliomas.

Functional Transient Receptor Potential Ankyrin 1 and Vanilloid 1 Ion Channels Are Overexpressed in Human Oral Squamous Cell Carcinoma.

Oral squamous cell carcinoma (OSCC) is a common cancer with poor prognosis. Transient Receptor Potential Ankyrin 1 (TRPA1) and Vanilloid 1 (TRPV1) receptors are non-selective cation channels expressed on primary sensory neurons and epithelial and immune cells. TRPV1 mRNA and immunopositivity, as well as TRPA1-like immunoreactivity upregulation, were demonstrated in OSCC, but selectivity problems with the antibodies still raise questions and their functional relevance is unclear. Therefore, here, we investigated TRPA1 and TRPV1 expressions in OSCC and analyzed their functions. TRPA1 and TRPV1 mRNA were determined by RNAscope in situ hybridization and qPCR. Radioactive 45Ca2+ uptake and ATP-based luminescence indicating cell viability were measured in PE/CA-PJ41 cells in response to the TRPA1 agonist allyl-isothiocyanate (AITC) and TRPV1 agonist capsaicin to determine receptor function. Both TRPA1 and TRPV1 mRNA are expressed in the squamous epithelium of the human oral mucosa and in PE/CA-PJ41 cells, and their expressions are significantly upregulated in OSCC compared to healthy mucosa. TRPA1 and TRPV1 activation (100 µM AITC, 100 nM capsaicin) induced 45Ca2+-influx into PE/CA-PJ41 cells. Both AITC (10 nM-5 µM) and capsaicin (100 nM-45 µM) reduced cell viability, reaching significant decrease at 100 nM AITC and 45 µM capsaicin. We provide the first evidence for the presence of non-neuronal TRPA1 receptor in the OSCC and confirm the expression of TRPV1 channel. These channels are functionally active and might regulate cancer cell viability.

Analgesic effects of the novel semicarbazide-sensitive amine oxidase inhibitor SZV 1287 in mouse pain models with neuropathic mechanisms: Involvement of transient receptor potential vanilloid 1 and ankyrin 1 receptors.

Semicarbazide-sensitive amine oxidase (SSAO) produces tissue irritants by deamination of primary amines, which activate transient receptor potential ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) receptors expressed predominantly on nociceptors. Since there are no data about its functions in pain, we studied the effects and mechanisms of action of our novel SSAO inhibitor and dual TRPA1/TRPV1 antagonist multi-target drug SZV 1287 in different pain models. Acute chemonociception was induced by TRPV1 and TRPA1 activation (resiniferatoxin and formalin, respectively), chronic arthritis by K/BxN serum transfer, traumatic mononeuropathy by sciatic nerve ligation. SZV 1287 (20 mg/kg i.p.) was investigated in C57BL/6J wildtype (WT), TRPA1- (TRPA1-/-) and TRPV1-deficient (TRPV1-/-) mice. Paw mechanonociception was measured by aesthesiometry, thermonociception by hot plate, nocifensive behavior by licking duration, volume by plethysmometry, myeloperoxidase activity by luminescence and plasma extravasation by fluorescence imaging, glia activation in pain-related brain regions by immunohistochemistry. SZV 1287 significantly inhibited both TRPA1 and TRPV1 activation-induced acute chemonociception and hyperalgesia. In K/BxN arthritis, daily SZV 1287 injections significantly decreased hyperalgesia, L4-L6 spinal dorsal horn microgliosis, edema and myeloperoxidase activity. SZV 1287-evoked antihyperalgesic and anti-edema effects were absent in TRPV1-/-, and remarkably reduced in TRPA1-/- mice. In contrast, myeloperoxidase-inhibitory effect was absent in TRPA1-/-, but not in TRPV1-/- animals. Acute SZV 1287 administration resulted in approximately 50% significant reduction of neuropathic hyperalgesia 7 days after nerve ligation, which was not observed in either TRPA1-/- or TRPV1-/- mice. SZV 1287 inhibits chronic inflammatory and neuropathic pain via TRPV1 and TRPA1/TRPV1 activation, respectively, highlighting its drug developmental potential.

Hemokinin-1 mediates anxiolytic and anti-depressant-like actions in mice.

The tachykinin NK1 receptor was suggested to be involved in psychiatric disorders, but its antagonists have failed to be effective as antidepressants in clinical trials. Hemokinin-1 (HK-1), the newest tachykinin, is present in several brain regions and activates the NK1 receptor similarly to substance P (SP), but acts also through other mechanisms. Therefore, we investigated the roles of the Tac4 gene-derived HK-1 in comparison with SP and neurokinin A (NKA) encoded by the Tac1 gene, as well as the NK1 receptor in anxiety and depression-like behaviors in mice. Mice lacking SP/NKA, HK-1 or the NK1 receptor (Tac1-/-, Tac4-/-, Tacr1-/-, respectively) compared to C57Bl/6 wildtypes (WT), and treatment with the NK1 antagonist CP99994 were used in the experiments. Anxiety was evaluated in the light-dark box (LDB) and the elevated plus maze (EPM), locomotor activity in the open field (OFT) tests. Hedonic behavior was assessed in the sucrose preference test (SPT), depression-like behavior in the tail suspension (TST) and forced swim (FST) tests. FST-induced neuronal responsiveness was evaluated with Fos immunohistochemistry in several stress-related brain regions. In the LDB, Tac4-/- mice spent significantly less, while Tacr1-/- and CP99994-treated mice spent significantly more time in the lit compartment. In the EPM only Tac4-/- showed reduced time in the open arms, but no difference was observed in any other groups. In the OFT Tac4-/- mice showed significantly reduced, while Tac1-/- and Tacr1-/- animals increased motility than the WTs, but CP99994 had no effect. NK1-/- consumed markedly more, while Tac4-/- less sucrose solution compared to WTs. In the TST and FST, Tac4-/- mice showed significantly increased immobility. However, depression-like behavior was decreased both in cases of genetic deletion and pharmacological blockade of the NK1 receptor. FST-induced neuronal activation in different nuclei involved in behavioral and neuroendocrine stress responses was significantly reduced in the brain of Tac4 -/- mice. Our results provide the first evidence for an anxiolytic and anti-depressant-like actions of HK-1 through a presently unknown target-mediated mechanism. Identification of its receptor and/or signaling pathways might open new perspectives for anxiolytic and anti-depressant therapies.

["Watermelon stomach" can be the cause of severe gastrointestinal bleeding]. / Masszív gastrointestinalis vérzést okozó "görögdinnyegyomor".

Irregular vascular dilatation in the antrum or the cardia of the stomach can be the cause of severe gastrointestinal bleeding. The first term for it - in the beginning of the 50's of the previous century - was GAVE (Gastric Antral Vascular Ectasia) since at that time no similar phenomenon had been registered before. A quarter of a century later, after publishing a few cases, a witty internist described it as "watermelon stomach" because the macroscopic picture is similarly looking as the aforesaid fruit's appearing. This rare condition occured in one of our patient with many comorbid diseases.

Osteosarcoma-Induced Pain Is Mediated by Glial Cell Activation in the Spinal Dorsal Horn, but Not Capsaicin-Sensitive Nociceptive Neurons: A Complex Functional and Morphological Characterization in Mice.

Bone cancer and its related chronic pain are huge clinical problems since the available drugs are often ineffective or cannot be used long term due to a broad range of side effects. The mechanisms, mediators and targets need to be identified to determine potential novel therapies. Here, we characterize a mouse bone cancer model induced by intratibial injection of K7M2 osteosarcoma cells using an integrative approach and investigate the role of capsaicin-sensitive peptidergic sensory nerves. The mechanical pain threshold was assessed by dynamic plantar aesthesiometry, limb loading by dynamic weight bearing, spontaneous pain-related behaviors via observation, knee diameter with a digital caliper, and structural changes by micro-CT and glia cell activation by immunohistochemistry in BALB/c mice of both sexes. Capsaicin-sensitive peptidergic sensory neurons were defunctionalized by systemic pretreatment with a high dose of the transient receptor potential vanilloid 1 (TRPV1) agonist resiniferatoxin (RTX). During the 14- and 28-day experiments, weight bearing on the affected limb and the paw mechanonociceptive thresholds significantly decreased, demonstrating secondary mechanical hyperalgesia. Signs of spontaneous pain and osteoplastic bone remodeling were detected both in male and female mice without any sex differences. Microglia activation was shown by the increased ionized calcium-binding adapter molecule 1 (Iba1) immunopositivity on day 14 and astrocyte activation by the enhanced glial fibrillary acidic protein (GFAP)-positive cell density on day 28 in the ipsilateral spinal dorsal horn. Interestingly, defunctionalization of the capsaicin-sensitive afferents representing approximately 2/3 of the nociceptive fibers did not alter any functional parameters. Here, we provide the first complex functional and morphological characterization of the K7M2 mouse osteosarcoma model. Bone-cancer-related chronic pain and hyperalgesia are likely to be mediated by central sensitization involving neuroinflammation via glial cell activation in the spinal dorsal horn, but not the capsaicin-sensitive sensory neuronal system.

[Classical pathology and basic concepts of the current WHO classification (5th edition) of central nervous system tumors]. / A központi idegrendszeri tumorok klasszikus patológiája és a jelenlegi WHO-klasszifikáció (5. kiadás) alapjai.

Considerable changes were introduced into the 5th World Health Organization (WHO) classification of central nervous system (CNS) tumors, published in 2021, including new entities, a clearer classification of previous categories, correlating better with clinical behavior and changes in nomenclature. The number of definitions based on molecular features in addition to histopathology continued to increase. Here, we highlight the basic principles of the 5th CNS WHO classification and discuss glial, glioneuronal, neuronal, choroid plexus, embryonal and pineal tumors, as well as meningiomas in more details. We pay special attention to new entities as well as altered criteria and designations. Our primary goal is to present the "classical" pathological aspects, but the inseparable molecular pathological features are also briefly discussed, to the absolutely necessary extent for comprehension. We aim to provide a guideline to understand the modern classification of CNS tumors for practitioners of neuro-oncology and neuropathology.

[Childhood brain tumors: diagnosis and therapy - comprehensive genomic profiling]. / Gyermekkori agydaganatok: diagnózis és terápia ­ komprehenzív genomikai profilozás.

With the advancement of molecular oncology, numerous new opportunities are available for the effective and efficient treatment of patients diagnosed with childhood brain tumors. This includes gene panel analysis aiding personalized treatment used in clinical trials, and the application of targeted therapy independent of tissue type (tumor agnostic therapy). Most personalized therapies inhibit certain kinases. In our review, we present the modern pathological diagnosis of childhood brain tumors, as well as the complex intracellular regulation of signal transduction pathways important from the point of view of clinical practice, and we describe their further targets defined on the basis of pharmacological characteristics of the pathway, based on international and our own results. Despite common mutations affecting kinases, personalized therapy is not available in many types of tumors. Through the example of childhood brain tumors, we demonstrate the expected future therapeutic significance of tyrosine kinases.

Hemokinin-1 is a mediator of chronic restraint stress-induced pain.

The Tac4 gene-derived hemokinin-1 (HK-1) binds to the NK1 receptor, similarly to Substance P, and plays a role in acute stress reactions and pain transmission in mice. Here we investigated Tac4 mRNA expression in stress and pain-related regions and its involvement in chronic restraint stress-evoked behavioral changes and pain using Tac4 gene-deleted (Tac4-/-) mice compared to C57Bl/6 wildtypes (WT). Tac4 mRNA was detected by in situ hybridization RNAscope technique. Touch sensitivity was assessed by esthesiometry, cold tolerance by paw withdrawal latency from 0°C water. Anxiety was evaluated in the light-dark box (LDB) and open field test (OFT), depression-like behavior in the tail suspension test (TST). Adrenal and thymus weights were measured at the end of the experiment. We found abundant Tac4 expression in the hypothalamic-pituitary-adrenal axis, but Tac4 mRNA was also detected in the hippocampus, amygdala, somatosensory and piriform cortices in mice, and in the frontal regions and the amygdala in humans. In Tac4-/- mice of both sexes, stress-induced mechanical, but not cold hyperalgesia was significantly decreased compared to WTs. Stress-induced behavioral alterations were mild or absent in male WT animals, while significant changes of these parameters could be detected in females. Thymus weight decrease can be observed in both sexes. Higher baseline anxiety and depression-like behaviors were detected in male but not in female HK-1-deficient mice, highlighting the importance of investigating both sexes in preclinical studies. We provided the first evidence for the potent nociceptive and stress regulating effects of HK-1 in chronic restraint stress paradigm. Identification of its targets might open new perspectives for therapy of stress-induced pain.

Novel, clinically relevant genomic patterns identified by comprehensive genomic profiling in ATRX-deficient IDH-wildtype adult high-grade gliomas.

Glioblastomas are the most common IDH-wildtype adult high-grade gliomas, frequently harboring mutations in the TERT gene promoter (pTERT) and utilizing the subsequent telomerase overexpression for telomere length maintenance. However, some rare cases show loss of ATRX and use alternative mechanisms of telomere lengthening. In this study, we performed the first complex genomic analysis specifically concentrating on the latter subgroup. Comprehensive genomic profiling of 12 ATRX-deficient and 13 ATRX-intact IDH-wildtype adult high-grade gliomas revealed that ATRX and pTERT mutations are mutually exclusive. DNMT3A alterations were confined to ATRX-deficient, while PTEN mutations to ATRX-intact cases. RAS-MAPK pathway alterations, including NF1 mutations, were more characteristic in the ATRX-deficient group. Variants of genes related to homologous recombination repair showed different patterns of affected genes. Two ATRX-deficient tumors with high tumor mutational burden and mismatch repair deficiency were found. One of these contained a novel fusion involving the NTRK2 and LRRFIP2 genes, while the other showed loss of MSH2 and MSH6 without genetic alterations in the encoding genes suggesting an epigenetic background. Genetic characteristics of ATRX-deficient IDH-wildtype adult high-grade gliomas suggest that these tumors are particularly intriguing targets of potential future therapeutic interventions including immunotherapies combined with MAPK pathway inhibition and DNA repair inhibitors.

Targeted histological evaluation shows high incidence of actinomyces infection in medication-related osteonecrosis of the jaws.

Medication-Related Osteonecrosis of the Jaws (MRONJ) is a difficult-to-treat complication of the therapy of osteoporosis and some malignancies cured with bisphosphonates and antiresorptive drugs. The pathomechanism is unclear, but there is increasing observation that Actinomyces infection may play a role in its development and progression. The aim of our study was to demonstrate that histological examination using a validated triple staining procedure for Actinomyces bacteria strains can detect a high rate of Actinomyces infection in patient's samples with MRONJ. 112 previously hematoxylin-eosin (HE) stained samples submitted with the clinical diagnosis of MRONJ were re-evaluated histologically using an appropriate triple special staining validated for the identification of Actinomyces infection. During the first evaluation, when pathologists did not specifically look for Actinomyces, only 8.93% of the samples were reported as positive. In contrast, re-evaluation with triple staining provided a yield of 93.7% positive samples, therefore, we suggest the triple special staining to be standard in MRONJ histology evaluation. These results show that if the clinician suspects Actinomyces infection and brings this to the attention of the pathologist, it could significantly increase the number of correct diagnoses. It serves as an aid for clinicians in therapeutic success of MRONJ by selecting a long-term adequate antibiotic medication which is suitable for the elimination of actinomyces infection.

The Nonsteroidal Anti-Inflammatory Drug Ketorolac Alters the Small Intestinal Microbiota and Bile Acids Without Inducing Intestinal Damage or Delaying Peristalsis in the Rat.

Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) induce significant damage to the small intestine, which is accompanied by changes in intestinal bacteria (dysbiosis) and bile acids. However, it is still a question of debate whether besides mucosal inflammation also other factors, such as direct antibacterial effects or delayed peristalsis, contribute to NSAID-induced dysbiosis. Here we aimed to assess whether ketorolac, an NSAID lacking direct effects on gut bacteria, has any significant impact on intestinal microbiota and bile acids in the absence of mucosal inflammation. We also addressed the possibility that ketorolac-induced bacterial and bile acid alterations are due to a delay in gastrointestinal (GI) transit. Methods: Vehicle or ketorolac (1, 3 and 10 mg/kg) were given to rats by oral gavage once daily for four weeks, and the severity of mucosal inflammation was evaluated macroscopically, histologically, and by measuring the levels of inflammatory proteins and claudin-1 in the distal jejunal tissue. The luminal amount of bile acids was measured by liquid chromatography-tandem mass spectrometry, whereas the composition of microbiota by sequencing of bacterial 16S rRNA. GI transit was assessed by the charcoal meal method. Results: Ketorolac up to 3 mg/kg did not cause any signs of mucosal damage to the small intestine. However, 3 mg/kg of ketorolac induced dysbiosis, which was characterized by a loss of families belonging to Firmicutes (Paenibacillaceae, Clostridiales Family XIII, Christensenellaceae) and bloom of Enterobacteriaceae. Ketorolac also changed the composition of small intestinal bile by decreasing the concentration of conjugated bile acids and by increasing the amount of hyodeoxycholic acid (HDCA). The level of conjugated bile acids correlated negatively with the abundance of Erysipelotrichaceae, Ruminococcaceae, Clostridiaceae 1, Muribaculaceae, Bacteroidaceae, Burkholderiaceae and Bifidobacteriaceae. Ketorolac, under the present experimental conditions, did not change the GI transit. Conclusion: This is the first demonstration that low-dose ketorolac disturbed the delicate balance between small intestinal bacteria and bile acids, despite having no significant effect on intestinal mucosal integrity and peristalsis. Other, yet unidentified, factors may contribute to ketorolac-induced dysbiosis and bile dysmetabolism.

Chronic treatment with rofecoxib but not ischemic preconditioning of the myocardium ameliorates early intestinal damage following cardiac ischemia/reperfusion injury in rats.

There is some recent evidence that cardiac ischemia/reperfusion (I/R) injury induces intestinal damage within days, which contributes to adverse cardiovascular outcomes after myocardial infarction. However, it is not clear whether remote gut injury has any detectable early signs, and whether different interventions aiming to reduce cardiac damage are also effective at protecting the intestine. Previously, we found that chronic treatment with rofecoxib, a selective inhibitor of cyclooxygenase-2 (COX-2), limited myocardial infarct size to a comparable extent as cardiac ischemic preconditioning (IPC) in rats subjected to 30-min coronary artery occlusion and 120-min reperfusion. In the present study, we aimed to analyse the early intestinal alterations caused by cardiac I/R injury, with or without the above-mentioned infart size-limiting interventions. We found that cardiac I/R injury induced histological changes in the small intestine within 2 h, which were accompanied by elevated tissue level of COX-2 and showed positive correlation with the activity of matrix metalloproteinase-2 (MMP-2), but not of MMP-9 in the plasma. All these changes were prevented by rofecoxib treatment. By contrast, cardiac IPC failed to reduce intestinal injury and plasma MMP-2 activity, although it prevented the transient reduction in jejunal blood flow in response to cardiac I/R. Our results demonstrate for the first time that rapid development of intestinal damage follows cardiac I/R, and that two similarly effective infarct size-limiting interventions, rofecoxib treatment and cardiac IPC, have different impacts on cardiac I/R-induced gut injury. Furthermore, intestinal damage correlates with plasma MMP-2 activity, which may be a biomarker for its early diagnosis.

Hemokinin-1 is an important mediator of pain in mouse models of neuropathic and inflammatory mechanisms.

The Tac4 gene-derived hemokinin-1 (HK-1) is present in pain-related regions and activates the tachykinin NK1 receptor, but with binding site and signaling pathways different from Substance P (SP). NK1 receptor is involved in nociception, but our earlier data showed that it has no role in chronic neuropathic hyperalgesia, similarly to SP. Furthermore, NK1 antagonists failed in clinical trials as analgesics due to still unknown reasons. Therefore, we investigated the role of HK-1 in pain conditions of distinct mechanisms using genetically modified mice. Chronic neuropathic mechanical and cold hyperalgesia after partial sciatic nerve ligation (PSL) were determined by dynamic plantar aesthesiometry and withdrawal latency from icy water, motor coordination on the accelerating Rotarod. Peripheral nerve growth factor (NGF) production was measured by ELISA, neuronal and glia cell activation by immunohistochemistry in pain-related regions. Acute somatic and visceral chemonocifensive behaviors were assessed after intraplantar formalin or intraperitoneal acetic-acid injection, respectively. Resiniferatoxin-induced inflammatory mechanical and thermal hyperalgesia by aesthesiometry and increasing temperature hot plate. Chronic neuropathic mechanical and cold hypersensitivity were significantly decreased in HK-1 deficient mice. NGF level in the paw homogenates of intact mice were significantly lower in case of HK-1 deletion. However, it significantly increased under neuropathic condition in contrast to wildtype mice, where the higher basal concentration did not show any changes. Microglia, but not astrocyte activation was observed 14 days after PSL in the ipsilateral spinal dorsal horn of wildtype, but not HK-1-deficient mice. However, under neuropathic conditions, the number of GFAP-positive astrocytes was significantly smaller in case of HK-1 deletion. Acute visceral, but not somatic nocifensive behavior, as well as neurogenic inflammatory mechanical and thermal hypersensitivity were significantly reduced by HK-1 deficiency similarly to NK1, but not to SP deletion. We provide evidence for pro-nociceptive role of HK-1, via NK1 receptor activation in acute inflammation models, but differently from SP-mediated actions. Identification of its targets and signaling can open new directions in pain research.

Higher susceptibility of somatostatin 4 receptor gene-deleted mice to chronic stress-induced behavioral and neuroendocrine alterations.

The somatostatin 4 receptor (sst4) is widely expressed in stress-related brain areas (e.g. hippocampus, amygdala) and regulates the emotional behavior in acute situations. Since its importance in chronic stress-induced complex pathophysiological alterations is unknown, we investigated the involvement of sst4 in the responsiveness to chronic variable stress (CVS). Sstr4 gene-deficient (Sstr4-/-) mice and their wildtype counterparts (Sstr4+/+) were used to examine the behavioral and neuroendocrine alterations as well as chronic neuronal activity (FosB expression) changes in response to CVS. In Sstr4+/+ mice, there was no behavioral response to the applied CVS paradigm. In contrast, immobility time in the tail suspension test increased after the CVS in the knockouts. In the forced swim test, Sstr4-/- animals showed increased baseline immobility and then it decreased after the CVS. Light-dark box and open field test behaviors and sucrose preference did not respond to the stress in the knockouts. Adrenal weights increased and thymus weights decreased in both Sstr4+/+ and Sstr4-/- mice demonstrating the effect of chronic stress. The relative adrenal weight of stressed knockouts increased to a greater extent, while relative thymus and body weights decreased only in the Sstr4-/- mice. Basal plasma corticosterone concentrations did not change after the CVS in either genotype. FosB immunopositivity in the central and basolateral amygdaloid nuclei was enhanced in stressed knockouts, but not in wild types. This is the first evidence that sst4 activation is involved in the behavioral and neuroendocrine alterations induced by chronic stress with a crucial role of plastic changes in the amygdala.

Somatostatin receptor subtype 4 activation is involved in anxiety and depression-like behavior in mouse models.

Somatostatin regulates stress-related behavior and its expression is altered in mood disorders. However, little is known about the underlying mechanisms, especially about the importance of its receptors (sst1-sst5) in anxiety and depression-like behavior. Here we analyzed the potential role of sst4 receptor in these processes, since sst4 is present in stress-related brain regions, but there are no data about its functional relevance. Genetic deletion of sst4 (Sstr4(-/-)) and its pharmacological activation with the newly developed selective non-peptide agonist J-2156 were used. Anxiety was examined in the elevated plus maze (EPM) and depression-like behavior in the forced swim (FST) and tail suspension tests (TST). Neuronal activation during the TST was monitored by Fos immunohistochemistry, receptor expression was identified by sst4(LacZ) immunostaining in several brain regions. Sstr4(-/-) mice showed increased anxiety in the EPM and enhanced depression-like behavior in the FST. J-2156 (100 µg/kg i.p.) exhibited anxiolytic effect in the EPM and decreased immobility in the TST. J-2156 alone did not influence Fos immunoreactivity in intact mice, but significantly increased the stress-induced Fos response in the dorsal raphe nucleus, central projecting Edinger-Westphal nucleus, periaqueductal gray matter, the magnocellular, but not the parvocellular part of the hypothalamic paraventricular nucleus, lateral septum, bed nucleus of the stria terminalis and the amygdala. Notably, sst4(LacZ) immunoreactivity occurred in the central and basolateral amygdala. Together, these studies reveal that sst4 mediates anxiolytic and antidepressant-like effects by enhancing the stress-responsiveness of several brain regions with special emphasis on the amygdala.

Neuropeptides in learning and memory.

Dementia conditions and memory deficits of different origins (vascular, metabolic and primary neurodegenerative such as Alzheimer's and Parkinson's diseases) are getting more common and greater clinical problems recently in the aging population. Since the presently available cognitive enhancers have very limited therapeutical applications, there is an emerging need to elucidate the complex pathophysiological mechanisms, identify key mediators and novel targets for future drug development. Neuropeptides are widely distributed in brain regions responsible for learning and memory processes with special emphasis on the hippocampus, amygdala and the basal forebrain. They form networks with each other, and also have complex interactions with the cholinergic, glutamatergic, dopaminergic and GABA-ergic pathways. This review summarizes the extensive experimental data in the well-established rat and mouse models, as well as the few clinical results regarding the expression and the roles of the tachykinin system, somatostatin and the closely related cortistatin, vasoactive intestinal polypeptide (VIP) and pituitary adenylate-cyclase activating polypeptide (PACAP), calcitonin gene-related peptide (CGRP), neuropeptide Y (NPY), opioid peptides and galanin. Furthermore, the main receptorial targets, mechanisms and interactions are described in order to highlight the possible therapeutical potentials. Agents not only symptomatically improving the functional impairments, but also inhibiting the progression of the neurodegenerative processes would be breakthroughs in this area. The most promising mechanisms determined at the level of exploratory investigations in animal models of cognitive disfunctions are somatostatin sst4, NPY Y2, PACAP-VIP VPAC1, tachykinin NK3 and galanin GALR2 receptor agonisms, as well as delta opioid receptor antagonism. Potent and selective non-peptide ligands with good CNS penetration are needed for further characterization of these molecular pathways to complete the preclinical studies and decide if any of the above described targets could be appropriate for clinical investigations.