The role of Neuropeptide Y in fear conditioning and extinction

While anxiety disorders are the brain disorders with the highest prevalence and constitute a major burden for society, a considerable number of affected people are still treated insufficiently. Thus, in an attempt to identify potential new anxiolytic drug targets, neuropeptides have gained considerable attention in recent years. Compared to classical neurotransmitters they often have a regionally restricted distribution and may bind to several distinct receptor subtypes. Neuropeptide Y (NPY) is a highly conserved neuropeptide that is specifically concentrated in limbic brain areas and signals via at least 5 different G-protein-coupled receptors. It is involved in a variety of physiological processes including the modulation of emotional-affective behaviors. An anxiolytic and stress-reducing property of NPY is supported by many preclinical studies. Whether NPY may also interact with processing of learned fear and fear extinction is comparatively unknown. However, this has considerable relevance since pathological, inappropriate and generalized fear expression and impaired fear extinction are hallmarks of human post-traumatic stress disorder and a major reason for its treatment-resistance. Recent evidence from different laboratories emphasizes a fear-reducing role of NPY, predominantly mediated by exogenous NPY acting on Y1 receptors. Since a reduction of fear expression was also observed in Y1 receptor knockout mice, other Y receptors may be equally important. By acting on Y2 receptors, NPY promotes fear extinction and generates a long-term suppression of fear, two important preconditions that could support cognitive behavioral therapies in human patients. A similar effect has been demonstrated for the closely related pancreatic polypeptide (PP) when acting on Y4 receptors. Preliminary evidence suggests that NPY modulates fear in particular by activation of Y1 and Y2 receptors in the basolateral and central amygdala, respectively. In the basolateral amygdala, NPY signaling activates inhibitory G protein-coupled inwardly-rectifying potassium channels or suppresses hyperpolarization-induced I(h) currents in a Y1 receptor-dependent fashion, favoring a general suppression of neuronal activity. A more complex situation has been described for the central extended amygdala, where NPY reduces the frequency of inhibitory and excitatory postsynaptic currents. In particular the inhibition of long-range central amygdala output neurons may result in a Y2 receptor-dependent suppression of fear. The role of NPY in processes of learned fear and fear extinction is, however, only beginning to emerge, and multiple questions regarding the relevance of endogenous NPY and different receptor subtypes remain elusive. Y2 receptors may be of particular interest for future studies, since they are the most prominent Y receptor subtype in the human brain and thus among the most promising therapeutic drug targets when translating preclinical evidence to potential new therapies for human anxiety disorders.

Revisiting the nanoformulation design approach for effective delivery of topotecan in its stable form: an appraisal of its in vitro Behavior and tumor amelioration potential

Topotecan (TPT) is indicated against a variety of solid tumors, but has restricted clinical use owing to associated pharmaceutical caveats. This study is focused at formulating a successful TPT PLGA nanosystem which ameliorates the rapid conversion of active lactone form of drug to its inactive carboxylate form and consequently improvises its efficacy. TPT PLGA nanoparticles were formulated by a double emulsion-solvent evaporation technique with sequential optimization to obtain desired particle size, PDI, zeta potential, and entrapment efficiency. Stability of TPT was ensured by maintaining an acidic pH in the drug-containing phase and the system was evaluated for in vitro-in vivo performance including cytotoxic potency. The optimized nanosystem had a particle size of 187.33 ± 7.50 nm, a PDI of 0.179 ± 0.05, and an entrapment efficiency of 56 ± 1.2%. Low pH in the interior of nanoparticles stabilized the drug to remain in its active lactone form and revealed a biphasic release pattern till 15 d. Additionally, an in vitro cytotoxicity testing as well as in vivo antitumor efficacy demonstrated a significant potential of higher proliferation inhibition as compared with neat drug (TPT). Thus, the investigation summarized an innovative simple tool for developing stable TPT NPs for effective delivery for treating solid tumors.

Structure and function of the amygdaloid NPY system: NPY Y2 receptors regulate excitatory and inhibitory synaptic transmission in the centromedial amygdala

The amygdala is essential for generating emotional-affective behaviors. It consists of several nuclei with highly selective, elaborate functions. In particular, the central extended amygdala, consisting of the central amygdala (CEA) and the bed nucleus of the stria terminalis (BNST) is an essential component actively controlling efferent connections to downstream effectors like hypothalamus and brain stem. Both, CEA and BNST contain high amounts of different neuropeptides that significantly contribute to synaptic transmission. Among these, neuropeptide Y (NPY) has emerged as an important anxiolytic and fear-reducing neuromodulator. Here, we characterized the expression, connectivity and electrophysiological function of NPY and Y2 receptors within the CEA. We identified several NPY-expressing neuronal populations, including somatostatin- and calretinin-expressing neurons. Furthermore, in the main intercalated nucleus, NPY is expressed primarily in dopamine D1 receptor-expressing neurons but also in interspersed somatostatin-expressing neurons. Interestingly, NPY neurons did not co-localize with the Y2 receptor. Retrograde tract tracing experiments revealed that NPY neurons reciprocally connect the CEA and BNST. Functionally, the Y2 receptor agonist PYY3-36, reduced both, inhibitory as well as excitatory synaptic transmission in the centromedial amygdala (CEm). However, we also provide evidence that lack of NPY or Y2 receptors results in increased GABA release specifically at inhibitory synapses in the CEm. Taken together, our findings suggest that NPY expressed by distinct populations of neurons can modulate afferent and efferent projections of the CEA via presynaptic Y2 receptors located at inhibitory and excitatory synapses.

NPY Y2 receptors in the central amygdala reduce cued but not contextual fear

The amygdala is fundamental for associative fear and extinction learning. Recently, also the central nucleus of the amygdala (CEA) has emerged as a site of plasticity actively controlling efferent connections to downstream effector brain areas. Although synaptic transmission is primarily mediated by glutamate and GABA, neuropeptides critically influence the overall response. While neuropeptide Y (NPY) acting via postsynaptic Y1 receptors exerts an important anxiolytic and fear-reducing action, the role of the predominantly presynaptic Y2 receptors is less defined. To investigate the role of Y2 receptors in the CEA we employed viral-vector mediated over-expression of the Y2 selective agonist NPY3-36 in fear conditioning and extinction experiments. NPY3-36 over-expression in the CEA resulted in reduced fear expression during fear acquisition and recall. Interestingly, this effect was blocked by intraperitoneal injection of a brain-penetrant Y2 receptor antagonist. Furthermore, over-expression of NPY3-36 in the CEA also reduced fear expression during fear extinction of CS-induced but not context-related fear. Again, fear extinction appeared delayed by peripheral injection of a Y2 receptor antagonist JNJ-31020028. Importantly, mice with over-expression of NPY3-36 in the CEA also displayed reduced spontaneous recovery and reinstatement, suggesting that Y2 receptor activation supports a permanent suppression of fear. Local deletion of Y2 receptors in the CEA, on the other hand, increased the expression of CS-induced freezing during fear recall and fear extinction. Thus, NPY inhibits fear learning and promotes cued extinction by reducing fear expression also via activation of presynaptic Y2 receptors on CEA neurons.

Nanopotentiated combination cancer therapy: Chemotherapeutic and chemosensitizer (2C approach)

An insight into the complex cancer pathophysiology reveals that a dependable amelioration of the disease could only be envisaged with a multipronged treatment approach. It is highly evident that singular chemotherapeutic agents used in clinical practice have shown limitations like severe side effects, MDR and are often associated with poor QOL while combinations of drugs have yielded better therapeutic outcomes. The current hypothesis takes it a step forward wherein a chemotherapeutic agent is combined with a natural chemosensitizer, both loaded into a nanopotentiated particulate system, which would eventually deliver the drug cargo at the target site with certitude. The encapsulated natural bioactive would then favorably act on the tumor milieu through multiple portals and chemosensibilize the cells towards cytotoxic action of the synthetic drug moiety. This 2C (chemotherapeutic and chemosensitizer) approach along with nanosystem's attributes like high payload, prolonged action and diminished side effects would proffer a more dependable treatment modality. In conclusion, the proposed system would be a value addition to the currently available armamentarium of cancer treatment tools.

Genetic variations of NLRP1: susceptibility in psoriasis

BACKGROUND

NACHT, LRR and PYD domain-containing protein (NLRP)1 is part of the inflammasome multiprotein complex involved in the production of interleukin (IL)-1β and IL-18, two cytokines strongly implicated in psoriasis pathogenesis. Genetic variations in NLRP1 are associated with a predisposition for chronic inflammatory conditions.

OBJECTIVES

The aim of the study was to investigate the role of genetic variation in the NLRP1 inflammasome in psoriasis susceptibility.

MATERIAL AND METHODS

Four haplotype-tagging single-nucleotide polymorphisms (SNPs) (rs6502867, rs8079034, rs878329 and rs12150220) were investigated by TaqMan allelic discrimination in a patient sample comprising 1847 individuals from 478 families and 802 healthy controls.

RESULTS

Using the transmission disequilibrium test, a significant increase in the transmission of the NLRP1 rs8079034C and rs878329C alleles to patients with psoriasis was demonstrated (P = 0·006 and P = 0·033, respectively). Furthermore, homozygosity for the rs878329C allele correlated with a younger age of onset. We also observed an increase in the expression of NLRP1 mRNA in the peripheral blood cells of patients with psoriasis. This was accompanied by a higher level of circulating IL-18 and appeared to be associated with the rs878329C allele.

CONCLUSIONS

Our data support the involvement of NLRP1 and the NLRP1 inflammasome in psoriasis susceptibility and further support the role of innate immunity in psoriasis.

Topotecan-tamoxifen duple PLGA polymeric nanoparticles: investigation of in vitro, in vivo and cellular uptake potential

The dual drug loaded poly(dl-lactic-co-glycolic acid) (PLGA(1)) nanoparticles (TOP-TAM NPs(2)) concurrently delivering topotecan hydrochloride (TOP(3)) and tamoxifen citrate (TAM(4)) were developed to achieve synergism for the treatment of breast cancer by enhancing the permeation of TOP through the gut and the cells present in the breast. TAM acted as P-glycoprotein (P-gp(5)) inhibitor, reduced the side effects of individual drugs by reducing the dose. The NPs were prepared by double emulsion (w/o/w) method. The optimized TOP-TAM NPs were found to have smooth and spherical morphology by using SEM(6) and TEM(7) technique. Similarly size of nanoparticles was found to be 151.2 ± 1.6 nm with 0.147 ± 0.03 polydispersity index (PDI(8)). The percentage entrapment efficiency of 95.17 ± 3.57 and 57.77 ± 2.2 was found for TAM and TOP respectively. The lyophillized nanoparticles under DSC(9) showed amorphous nature of both TOP and TAM. In an in vitro release study the release of drugs from TOP-TAM NPs was found to follow the Higuchi pattern. The ex vivo gut permeation study revealed that the TAM enhanced the permeation of TOP and increased its bioavailability by 1.9 folds. The permeation and activity of combination of drugs were further confirmed by carrying out cell line studies on MCF-7 cells.

Potential contribution of monoamine oxidase a gene variants in ADHD and behavioral co-morbidities: scenario in eastern Indian probands

Attention deficit hyperactivity disorder (ADHD) is the most frequently diagnosed behavioral disorder in children with a high frequency of co-morbid conditions like conduct disorder (CD) and oppositional defiant disorder (ODD). These traits are controlled by neurotransmitters like dopamine, serotonin and norepinephrine. Monoamine oxidase A (MAOA), a mitochondrial enzyme involved in the degradation of amines, has been reported to be associated with aggression, impulsivity, depression, and mood changes. We hypothesized that MAOA can have a potential role in ADHD associated CD/ODD and analyzed 24 markers in a group of Indo-Caucasoid subjects. ADHD probands and controls (N = 150 each) matched for ethnicity and gender were recruited following the Diagnostic and Statistical Manual for Mental Disorders-IV. Appropriate scales were used for measuring CD and ODD traits. Markers were genotyped by PCR-based methods and data obtained analyzed using the Cocaphase program under UNPHASED. Only eight markers were found to be polymorphic. rs6323 "G" allele showed higher frequencies in ADHD (P = 0.0023), ADHD + CD (P = 0.03) and ADHD + ODD (P = 0.01) as compared to controls. Haplotype analysis revealed statistically significant difference for three haplotypes in ADHD cases (P < 0.02). Statistically significant differences were also noticed for haplotypes in ADHD + CD and ADHD + ODD cases (P < 0.01). LD analysis showed significant variation in different groups. Multidimensionality reduction analysis showed independent as well as interactive effects of markers. Genotypes showed correlation with behavioral problems in ADHD and ADHD + CD. We interpret that MAOA gene variants may contribute to the etiology of ADHD as well as associated co-morbid CD and ODD in this ethnic group.

Mitochondrial electron transport chain complexes, catalase and markers of oxidative stress in platelets of patients with severe aluminum phosphide poisoning

Aluminum phosphide (ALP), a widely used fumigant and rodenticide, leads to high mortality if ingested. Its toxicity is due to phosphine that is liberated when it comes in contact with moisture. The exact site or mechanism of action of phosphine is not known, although it is widely believed that it affects mitochondrial oxidative phosphorylation. Basic serum biochemical parameters, activity of mitochondrial complexes, antioxidant enzymes and parameters of oxidative stress were estimated in the platelets of 21 patients who developed severe poisoning following ALP ingestion. These parameters were compared with 32 healthy controls and with 22 patients with shock due to other causes (cardiogenic shock (11), septic shock (9) and hemorrhagic shock (2)). The serum levels of creatine kinase-muscle brain and lactate dehydrogenase were higher in patients poisoned with ALP, whereas a significant decrease was observed in the activities of mitochondrial complexes I, II and IV. The activity of catalase was lower but the activities of superoxide dismutase and glutathione peroxidase were unaffected in them. A significant increase in lipid peroxidation and protein carbonylation was observed, whereas total blood thiol levels were lower. In patients severely poisoned with ALP, not only cytochrome c oxidase but also other complexes are involved in mitochondrial electron transport, and enzymes are also inhibited.

NPY controls fear conditioning and fear extinction by combined action on Y₁ and Y₂ receptors

BACKGROUND AND PURPOSE

Neuropeptide Y (NPY) and its receptors have been implicated in the control of emotional-affective processing, but the mechanism is unclear. While it is increasingly evident that stimulation of Y₁ and inhibition of Y₂ receptors produce prominent anxiolytic and antidepressant effects, the contribution of the individual NPY receptor subtypes in the acquisition and extinction of learned fear are unknown.

EXPERIMENTAL APPROACH

Here we performed Pavlovian fear conditioning and extinction in NPY knockout (KO) and in NPY receptor KO mice.

KEY RESULTS

NPY KO mice display a dramatically accelerated acquisition of conditioned fear. Deletion of Y₁ receptors revealed only a moderately accelerated acquisition of conditioned fear, while lack of Y₂ receptors was without any effect on fear learning. However, the strong phenotype seen in NPY KO mice was reproduced in mice lacking both Y₁ and Y₂ receptors. In addition, NPY KO mice showed excessive recall of conditioned fear and impaired fear extinction. This behaviour was replicated only after deletion of both Y₁ and Y₂ receptors. In Y₁ receptor single KO mice, fear extinction was delayed and was unchanged in Y₂ receptor KO mice. Deletion of NPY and particularly Y₂ receptors resulted in a generalization of conditioned fear.

CONCLUSIONS AND IMPLICATIONS

Our data demonstrate that NPY delays the acquisition, reduces the expression of conditioned fear while promoting fear extinction. Although these effects appear to be primarily mediated by Y₁ receptors, the pronounced phenotype of Y₁Y₂ receptor double KO mice suggests a synergistic role of Y₂ receptors in fear acquisition and in fear extinction.

Bilateral symmetrical facial swelling owing to tuberculous gummas

Metastatic tuberculous abscesses and gummas are unusual forms of cutaneous tuberculosis. They result from haematogeneous spread of the mycobacterium from a primary focus during a period of impaired immunity. A 5-year-old boy is reported who presented with spinal tuberculosis and bilateral subcutaneous swelling of the cheeks owing to tuberculous gummas.

Prognostic value of FLT3 mutations among different cytogenetic subgroups in acute myeloid leukemia (AML)

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Background: Mutations of the FLT3 gene (in special internal tandem duplication -ITD) are common in normal karyotype AML (NK-AML) and are associated with shorter relapse free and overall survival (OS). The frequency of FLT3 mutations is lower in other cytogenetic subgroups and the impact on outcome is unclear. Methods: The records of patients (pts) with newly diagnosed AML (from 2003 to 2007) were reviewed. Pts were divided among three cytogenetic subgroups: Good-risk (t(8;21), Inv(16)/t(16;16)) Intermediate-Risk (Diploid,-Y) and Poor Risk (-5,-7, 11q abnormalities). FLT3 ITD and tyrosine kinase domain (TKD) mutations were determined on baseline DNA samples by a PCR based method with 1% sensitivity. Since the frequencies of FLT3 mutations were lower in good- and poor-risk subgroups, ITD/TKD mutations were considered together in the analysis, while in the intermediate risk group they were analyzed separately. Survival curves stratified by FLT3 mutation were estimated by Kaplan Meier plots and compared by logrank test. A Cox model was fit for OS, and non-significant variables were eliminated in a step-down fashion with a p- value cut-off of p = .10. Results: A total of 481 pts were included (65 pts=good risk, 272 pts=intermediate risk and 144 pts= poor risk). Prevalence of FLT3 mutations is shown in the Table. No difference was found in median OS between FLT3-mutated and FLT3- wild type pts in the good risk group (not reached (NR) vs NR, P = 0.57) nor in the poor risk group (55 vs 24 weeks, P = 0.44). In intermediate risk, OS was worse in FLT3-ITD positive pts (33 vs 89 weeks, P < 0.0001) but not in FLT3-TKD positive pts (77 vs 70 weeks, P = 0.89). In the Cox model, FLT3 mutations were prognostic for OS only in intermediate risk pts with FLT3-ITD (HR 2.63, P < 0.0001). Conclusions: In our cohort of pts, FLT3 mutations did not have a prognostic impact in AML with good and poor risk karyotype.

[Table: see text]

No significant financial relationships to disclose.

Chronic myeloid leukemia (CML) with e1a2 BCR-ABL fusion transcript type: Analysis of characteristics, outcomes, and prognostic significance

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Background: The most common BCR-ABL fusion transcripts in CML are e13a2 (b2a2) and e14a2 (b3a2). Rarely, other transcripts like e1a2 are seen. Currently, there is no published series of data on efficacy of imatinib or other tyrosine kinase inhibitors (TKIs) in CML with e1a2. Methods: We analyzed records of 1,292 CML patients treated with TKI at our institution between January 2000 and November 2008. Results: 14 CML patients with e1a2 transcripts were identified, 9 in chronic phase (CP), 1 in accelerated phase (AP), and 4 in blast phase (BP). Median age at diagnosis was 60 (range 28–86) years, median follow-up 39.5 (range 2–109) months. Of the 9 in CP, 3 received interferon and then imatinib after interferon failure, 6 received TKI as first-line therapy (5 imatinib, 1 nilotinib): 5 achieved CHR only, 1 CCyR, 1 MCyR, 1 PCyR, and 1 did not respond to imatinib. 5 patients (2 post-interferon failure - 1 in CHR, 1 in PCyR; 3 frontline imatinib - 1 in CHR, 1 in CCyR, 1 non-responder) progressed to advanced phases (3 myeloid BP, 1 lymphoid BP, 1 AP) at a median 48 (range 4–92) months after CML diagnosis; with only 1 alive and in CMR after allogeneic SCT. AP patient received various TKIs sequentially and achieved only CHR with disappearance of clonal evolution. BP patients received Hyper-CVAD+imatinib/dasatinib or idarubicin+Ara-C; 2 did not respond, 1 had CCyR lasting 12 months with Hyper-CVAD+Imatinib and 1 had CMR after allogeneic SCT lasting 2 months. In all 14 patients, cytogenetic responses lasted 1–9 months before being lost and none (except 2) achieved MMR or CMR on imatinib or other TKI therapy. Six patients (5 CP, 1 AP) were alive at a median 39 (range 2–85) months after initial diagnosis: 4 with CHR (2 on imatinib, 1 nilotinib, 1 bosutinib), 1 with MCyR on imatinib, and 1 with CMR after allogeneic SCT. Conclusions: CML with e1a2 BCR-ABL fusion transcripts is rare and is associated with an inferior outcome to therapy with TKI, with responses being usually short-lived. These patients need to be identified as high-risk patients and monitored closely for efficacy during therapy with TKI.

No significant financial relationships to disclose.

An animal model for studying endoscopic ultrasound changes of early chronic pancreatitis with histologic correlation: a pilot study

BACKGROUND AND STUDY AIMS

Due to the difficulty in obtaining pancreatic tissue for histology in humans, we developed an animal model for studying endoscopic ultrasound (EUS) changes of early chronic pancreatitis. This report on the animal model describes the serial changes of early chronic pancreatitis by EUS and correlates results with histology.

MATERIALS AND METHODS

Four 60 - 80-lb dogs were used in the study. Pancreatic EUS was performed to provide baseline images prior to any procedure. At laparotomy, a guide wire was passed into the pancreatic duct, and a 5-Fr pancreatic stent was introduced over the wire into the pancreatic duct. Animals were divided into two survival groups - 2 weeks and 4 weeks. In each group, EUS examination was performed under anesthesia to image the pancreas and then followed by euthanasia. Sequential pancreatic sections were taken from the head, body, and tail of the pancreas. EUS findings were correlated with histologic results with respect to degree of fibrosis, inflammation, and edema.

RESULTS

At baseline EUS, the pancreas appeared homogeneous with only a few echogenic septations and echogenic margins of the main pancreatic duct. At 2 and 4 weeks poststenting, EUS images showed the following changes: lobularity, hyper and hypoechoic foci, increased echogenic septations, visible pancreatic duct side branches, and irregular margins of the main pancreatic duct.

CONCLUSIONS

The dog model for chronic pancreatitis appears to be a promising method for studying sequential changes of chronic pancreatitis by EUS and correlating results with histology.