Regional specificity of synaptic plasticity deficits in a knock-in mouse model of DYT1 dystonia.

DYT1 dystonia is a movement disorder caused by a deletion in the C-terminal of the protein torsinA. It is unclear how torsinA mutation might disrupt cellular processes encoding motor activity, and whether this impairment occurs in specific brain regions. Here, we report a selective impairment of corticostriatal synaptic plasticity in knock-in mice heterozygous for Δ-torsinA (Tor1a(+/Δgag) mice) as compared to controls (Tor1a(+/+) mice). In striatal spiny neurons from Tor1a(+/Δgag) mice, high-frequency stimulation failed to induce long-term depression (LTD), whereas long-term potentiation (LTP) exhibited increased amplitude. Of interest, blockade of D2 dopamine receptors (D2Rs) increased LTP in Tor1a(+/+) mice to a level comparable to that measured in Tor1a(+/Δgag) mice and normalized the levels of potentiation across mouse groups. A low-frequency stimulation (LFS) protocol was unable to depotentiate corticostriatal synapses in Tor1a(+/Δgag) mice. Muscarinic M1 acetylcholine receptor (mAChR) blockade rescued plasticity deficits. Additionally, we found an abnormal responsiveness of cholinergic interneurons to D2R activation, consisting in an excitatory response rather than the expected inhibition, further confirming an imbalance between dopaminergic and cholinergic signaling in the striatum. Conversely, synaptic activity and plasticity in the CA1 hippocampal region were unaltered in Tor1a(+/Δgag) mice. Importantly, the M1 mAChR-dependent enhancement of hippocampal LTP was unaffected in both genotypes. Similarly, both basic properties of dopaminergic nigral neurons and their responses to D2R activation were normal. These results provide evidence for a regional specificity of the electrophysiological abnormalities observed and demonstrate the reproducibility of such alterations in distinct models of DYT1 dystonia.

Identifying a healthy oral microbiome through metagenomics.

We present the results of an exploratory study of the bacterial communities from the human oral cavity showing the advantages of pyrosequencing complex samples. Over 1.6 million reads from the metagenomes of eight dental plaque samples were taxonomically assigned through a binning procedure. We performed clustering analysis to discern if there were associations between non-caries and caries conditions in the community composition. Our results show a given bacterial consortium associated with cariogenic and non-cariogenic conditions, in agreement with the existence of a healthy oral microbiome and giving support to the idea of dental caries being a polymicrobial disease. The data are coherent with those previously reported in the literature by 16S rRNA amplification, thus giving the chance to link gene functions with taxonomy in further studies involving larger sample numbers.

Characterization of a novel oral glucocorticoid system and its possible role in disease.

Synthetic corticosteroids are used widely for the treatment of a variety of diseases of the mouth. However, little is known as to whether the oral mucosa is able to modulate the local concentration of active corticosteroids or to produce steroids de novo. This has important clinical implications, because tissue-specific regulation of glucocorticoids is a key determinant of the clinical efficacy of these drugs. In the present study, we show that oral fibroblasts and keratinocytes expressed ACTH receptor (MC2R), glucocorticoid receptor (GR), and 11ß-hydroxysteroid dehydrogenases (11ß-HSDs). Unlike keratinocytes, fibroblasts lacked 11ß-HSD2 and could not effectively deactivate exogenously administered cortisol. However, both cell types were able not only to activate cortisone into the active form cortisol, but also to synthesize cortisol de novo following stimulation with ACTH. 11ß-HSD2, the enzyme controlling cortisol deactivation, exhibited different patterns of expression in normal (squamous epithelium and salivary glands) and diseased oral mucosa (squamous cell carcinoma and mucoepidermoid carcinoma). Blocking of endogenous cortisol catabolism in keratinocytes with the 11ß-HSD2 inhibitor 18ß-glycyrrhetinic acid mimicked the effect of exogenous administration of hydrocortisone and partially prevented the detrimental effects induced by pemphigus vulgaris sera. Analysis of the data demonstrates that a novel, non-adrenal glucocorticoid system is present in the oral mucosa that may play an important role in disease.

Role of human tissue kallikrein in gastrointestinal stromal tumour invasion.

BACKGROUND: Human tissue kallikrein (hK1) generates vasodilator kinins from kininogen and promotes angiogenesis by kinin-dependent and kinin-independent mechanisms. Here, we investigate the expression and functional relevance of hK1 in human gastrointestinal stromal tumour (GIST). METHODS: Vascularisation and hK1 expression of GIST samples were assessed by immunohistochemistry. In two GIST cell lines, hK1 expression was assessed by PCR, and hK1 protein levels and activity were measured by ELISA and an amidolytic assay, respectively. The effect of hK1 silencing, inhibition or overexpression on GIST cell proliferation, migration and paracrine induction of angiogenesis was studied. Finally, local and systemic levels of hK1 were assessed in mice injected with GIST cells. RESULTS: Human tissue kallikrein was detected in 19 out of 22 human GIST samples. Moreover, GIST cells express and secrete active hK1. Titration of hK1 demonstrated its involvement in GIST invasive behaviour, but not proliferation. Furthermore, hK1 released by GIST cells promoted endothelial cell migration and network formation through kinin-dependent mechanisms. Gastrointestinal stromal tumour implantation in nude mice resulted in local and systemic hK1 expression proportional to tumour dimension. CONCLUSIONS: Human tissue kallikrein is produced and released by GIST and participates in tumour invasion. Further studies are needed to validate hK1 as a diagnostic biomarker and therapeutic target in GIST.

The London APP mutation (Val717Ile) associated with early shifting abilities and behavioral changes in two Italian families with early-onset Alzheimer's disease.

BACKGROUND/AIMS: Mutations in the amyloid precursor protein gene were the first to be recognized as a cause of Alzheimer's disease (AD). METHODS: We describe 2 Italian families showing the missense mutation in exon 17 of the amyloid precursor protein gene on chromosome 21 (Val717Ile), known as London mutation. RESULTS: In 1 family, this mutation was responsible for AD in 3 out of 7 siblings and it is also present in a fourth sibling who has only shown signs of executive dysfunction so far. Two subjects of the other family with AD diagnosis were carriers of the same mutation. CONCLUSION: All AD subjects showed a cognitive profile characterized by early impairment in long-term memory, shifting abilities and affective symptoms beginning in the fifth decade of life.

The pea aphid phylome: a complete catalogue of evolutionary histories and arthropod orthology and paralogy relationships for Acyrthosiphon pisum genes.

Phylogenetic analyses serve many purposes, including the establishment of orthology relationships, the prediction of protein function and the detection of important evolutionary events. Within the context of the sequencing of the genome of the pea aphid, Acyrthosiphon pisum, we undertook a phylogenetic analysis for every protein of this species. The resulting phylome includes the evolutionary relationships of all predicted aphid proteins and their homologues among 13 other fully-sequenced arthropods and three out-group species. Subsequent analyses have revealed multiple gene expansions that are specific to aphids and have served to transfer functional annotations to 4058 pea aphid genes that display one-to-one orthology relationships with Drosophila melanogaster annotated genes. All phylogenies and alignments are accessible through the PhylomeDB database. Here we provide a description of this dataset and provide some examples on how can it be exploited.

Enhanced expression of the neuronal K+/Cl- cotransporter, KCC2, in spontaneously depressed Flinders Sensitive Line rats.

We used Flinder Sensitive Line (FSL) rats, a genetic model of unipolar depression, to examine whether changes in central GABAergic transmission are associated with a depressed phenotype. FSL rats showed an increased behavioral response to low doses of diazepam, as compared to either Sprague Dawley (SD) or Flinder Resistant Line (FRL) rats used as controls. Diazepam at a dose of 0.3 mg/kg, i.p., induced a robust impairment of motor coordination in FSL rats, but was virtually inactive in SD or FRL rats. The increased responsiveness of FSL rats was not due to changes in the brain levels of diazepam or its active metabolites, or to increases in the number or affinity of benzodiazepine recognition sites, as shown by the analysis of [(3)H]-flunitrazepam binding in the hippocampus, cerebral cortex or cerebellum. We therefore examined whether FSL rats differed from control rats for the expression levels of the K(+)/Cl(-) cotransporter, KCC2, which transports Cl(-) ions out of neurons, thus creating the concentration gradient that allows Cl(-) influx through the anion channel associated with GABA(A) receptors. Combined immunoblot and immunohistochemical data showed a widespread increase in KCC2 expression in FSL rats, as compared with control rats. The increase was more prominent in the cerebellum, where KCC2 was largely expressed in the granular layer. These data raise the interesting possibility that a spontaneous depressive state in animals is associated with an amplified GABAergic transmission in the CNS resulting from an enhanced expression of KCC2.

The actin-bundling protein fascin is overexpressed in colorectal adenomas and promotes motility in adenoma cells in vitro.

BACKGROUND: Fascin is overexpressed in many cancers, including colorectal, but its role in the malignant transformation of benign colorectal adenomas is unclear. METHODS: Immunohistochemical analysis of fascin expression was carried out in resected human colorectal adenoma specimens. The effects of forced overexpression of fascin on adenoma cell motility were also analysed. RESULTS: We show fascin overexpression in adenomas increasing with tumour size, histological type, and degree of dysplasia and increased cell motility in adenoma cell lines following fascin transfection. CONCLUSION: These data suggest an important role for fascin in the malignant progression of colorectal tumours.

Galactosilated dopamine increases attention without reducing activity in C57BL/6 mice.

Different strategies can be used to carry dopamine into the brain such as L-Dopa precursors or galactosilated form of DA (GAL-DA). The aim of this study was to investigate whether GAL-DA would reduce hyperactivity and increase non-selective attention (NSA) in a mouse model of attention deficit hyperactivity disorder (ADHD), as, i.e. C57BL/6 as did in NHE rats. Here we report that GAL-DA increases NSA in a spatial novelty in C57BL/6 mice. They received a single i.p. injection of GAL-DA (10 mg/kg or 100 mg/kg) or equimolar galactose vehicle. Another mouse strain the Swiss albino was introduced as inbred control group. Three hours after last injection mice were tested in a Làt-maze for 30-min. Behaviour was analyzed for horizontal (traveled distance) and vertical activity (orienting frequency and scanning durations) which shares cognitive and non-cognitive nature, respectively. Ten milligram per kilograms of GAL-DA, increases scanning duration in C57BL/6 mice. Thus a low dose of GAL-DA increases NSA without reducing hyperactivity in this mouse model of ADHD.

Inhibition of COX-2 with NS-398 decreases colon cancer cell motility through blocking epidermal growth factor receptor transactivation: possibilities for combination therapy.

UNLABELLED: The use of non-steroidal anti-inflammatory drugs has proved of great interest in the prevention and treatment of colorectal cancer, although their precise mechanisms of action remain unclear. Overexpression of cyclooxygenase-2 (COX-2) and subsequent prostaglandin production promote metastasis and have been shown to increase cell motility in vitro. OBJECTIVE: We have aimed to elucidate whether specific inhibition of COX-2 with NS-398 (NS-398 is a selective inhibitor of COX-2) would be able to inhibit motility of colorectal cancer cells and whether this was modulated through epidermal growth factor receptor (EGFR) transactivation. MATERIALS AND METHODS: A transwell filter assay was used to study cell motility. Expression of COX-2, EGFR phosphorylation and prostaglandin E(2) (PGE(2)) receptors were assessed by Western blot analysis and reverse transcriptase-polymerase chain reaction. PGE(2) concentrations after NS-398 treatment were estimated by enzyme immunoassay. RESULTS: Treatment with NS-398 significantly reduced PGE(2) levels and reduced cell migration in the HT29 and HCA7 colorectal carcinoma cell lines and this effect was rescued by addition of PGE(2). Furthermore, specific inhibition of COX-2 with NS-398 reduced EGFR phosphorylation in colorectal cancer cells. Direct inhibition of EGFR activity with AG1478 reduced PGE(2)-stimulated motility, clearly demonstrating that PGE(2 )acts via the EGFR-signalling pathway. The novel combination of NS-398 and AG1478 dramatically reduced migration of colorectal cancer cells. CONCLUSION: The data presented indicate that the use of NS-398 in chemoprevention and adjuvant therapy for colorectal cancer may work in part, through the inhibition of cell motility. Furthermore, our data suggest that the combined use of non-steroidal anti-inflammatory drugs with EGFR antagonists could be explored further for future use in the clinic.

Characterisation of adherens and tight junctional molecules in normal animal larynx; determining a suitable model for studying molecular abnormalities in human laryngopharyngeal reflux.

BACKGROUND: The disruption of intercellular junctions in the larynx is a pathological feature of laryngopharyngeal reflux (LPR). Good experimental models are necessary to gain greater insight into the molecular mechanisms and alterations that result from abnormal exposure of the laryngeal epithelium to acid refluxate. AIMS: To characterise laryngeal tissues from different species to determine the most suitable for use in experimental studies of LPR. METHODS: Human and non-human laryngeal tissues (mouse, rat, guinea pig, porcine, and rabbit) were studied. Histological characterisation was performed by light microscopy. The expression and subcellular localisation of adherens junctional molecules (E-cadherin and beta catenin) was evaluated by immunohistochemistry, and tight junction molecules (occludin and zonula occludens 1 (ZO-1)) by western blotting. The ultrastructural features of porcine and human tissue were assessed by electron microscopy. RESULTS: Porcine tissue revealed both respiratory-type and stratified squamous epithelium, as seen in the human larynx. The expression and subcellular localisation of the E-cadherin-catenin complex was detected in all species except mouse and rat. The pattern of ZO-1 and occludin expression was preserved in all species. CONCLUSION: The expression of intercellular junctional complexes in porcine epithelium is similar to that seen in humans. These results confirm the suitability of these species to study molecular mechanisms of LPR in an experimental system.

Activated Akt expression in breast cancer: correlation with p53, Hdm2 and patient outcome.

Activation of protein kinase-B/Akt (pAkt) is mediated by oestrogen and involves HER-2 in vitro, to phosphorylate Hdm2 and influence p53 cytoplasmic localisation and degradation. Expression of all active Akt isoforms (pAkt) were examined, together with p53/Hdm2 subcellular expression in invasive ductal breast cancers (IDCs), to evaluate whether in vitro findings were related to clinical data and determine the effect on outcome. Immunohistochemical expression of serine 473 specific phosphorylated Akt (pAkt) isoforms (Akt-1,2,3) was evaluated in 97 patients, together with subcellular expression of p53/Hdm2. The results show that pAkt was evaluable in 95 patients with cytoplasmic expression in 81% and more likely to be associated with larger tumours (P=0.007), with no correlation with HER-2 expression. pAkt correlated with increasing levels of cytoplasmic p53 (P=0.025) and was associated with a reduced disease-free survival (P=0.04; univariate). In conclusion, pAkt has implications in breast cancer growth through mechanisms inactivating p53 with an association with immunohistochemical p53 expression, which is preferentially cytoplasmic. Despite in vitro associations, pAkt appears to be a variable marker of HER-2 expression.

p14ARF expression in invasive breast cancers and ductal carcinoma in situ--relationships to p53 and Hdm2.

INTRODUCTION: p14ARF stabilises nuclear p53, with a variable expression of p14ARF mRNA in breast cancers. In vitro, nuclear p14ARF binds Hdm2 to block Hdm2-dependent nucleocytoplasmic shuttling of p53, which is required before cytoplasmic degradation of p53. p14ARF is negatively regulated by p53 and through p53-independent pathways. No studies have yet examined levels of p14ARF protein expression in breast cancer and their relationship to Hdm2/p53 immunoreactivity or subcellular localisation. Previously, immunohistochemical expression of cytoplasmic p14ARF, p53 and Hdm2 has been described. HER-2 (c-erbB2/neu) predicts prognosis and interacts with the p14ARF/Hdm2 pathway to inactivate p14ARF and to influence Hdm2 activity and localisation. This study examined p14ARF and p53/Hdm2 expression and subcellular localisation by using immunohistochemistry in a series of invasive ductal breast cancers (IDCs) with concomitant ductal carcinoma in situ (DCIS), to evaluate whether findings in vitro were related to clinicopathological parameters such as HER-2 and their effect on patient outcome. METHODS: The 4C6 anti-p14ARF monoclonal antibody and Dako Envision Plus system were used to evaluate p14ARF expression in 103 patients; p53/Hdm2 staining was performed. RESULTS: p14ARF was evaluable in 96 patients, with nuclear p14ARF expression (modified Quick-score > or = 3) in 79% (n = 76) of IDCs and in associated DCIS in 74 patients. Cytoplasmic p14ARF was detectable in 23 breast cancers. Nuclear and cytoplasmic p14ARF showed no correlation with p53 subcellular immunoreactivity. Increasing levels of cytoplasmic p14ARF were associated with nuclear and cytoplasmic Hdm2 expression (P < 0.001). Subcellular ARF expression was not associated with clinicopathological parameters, and although not an independent prognosticator, these preliminary findings suggest that cytoplasmic p14ARF might be associated with a better overall survival (P = 0.09; log rank). The association between HER-2 positivity and nuclear p14ARF (P = 0.038), as well as nuclear Hdm2 (P = 0.019), reflects the in vitro findings of HER-2 interaction with the ARF/Hdm2 pathway. Cytoplasmic p53 and Hdm2 expression might have biological implications, through an association of cytoplasmic p53 with increased tumour proliferation (P = 0.005), and an improved overall survival (P = 0.002, log rank) in cytoplasmic Hdm2-expressing tumours, that independently predict favourable overall survival (P = 0.02) and disease-free survival (P = 0.03). CONCLUSIONS: Nuclear p14ARF expression is similar in IDCs and DCIS and is associated with Hdm2 immunoreactivity. Nuclear p14ARF and Hdm2 might be regulated by HER-2. Clearly, our findings in vivo suggest a complexity of p14ARF/Hdm2 and p53 pathways in which consideration of cytoplasmic p14ARF and Hdm2 might have tumorigenic implications.

Biochemical analysis and subcellular distribution of E-cadherin-catenin in adenocarcinomas of the gastro-oesophageal junction.

BACKGROUND: Disturbances in the expression or structure of E-cadherin-catenin, a cell-cell adhesion complex, perturb its cell adhesive function. MATERIALS AND METHODS: We studied the expression and distribution of the E-cadherin-catenin complex in 24 adenocarcinomas of the gastro-oesophageal junction (GOJ) by immunohistochemistry and Western blotting of the Triton X-100-soluble (membrane bound) and insoluble fractions (cytoskeleton bound). RESULTS: Immunohistochemistry demonstrated redistribution of E-cadherin, alpha-, beta- and gamma-catenin from the membrane to the cytoplasm in 13/24 (54%), 18/24 (75%), 16/24 (67%) and 15/24 (63%) tumours, respectively. Five tumours showed nuclear localisation of beta-catenin. Western blotting showed redistribution between the TX-100 soluble and insoluble fraction of E-cadherin and the catenins in 5/11 (45%), 4/10 (40%), 5/11 (45%) and 5/11 (45%) tumours, respectively. CONCLUSION: Loss of membrane bound E-cadherin-catenin is frequently observed in adenocarcinomas of the GOJ and this may reflect loss of function of the E-cadherin-catenin complex in these cancers.

Prenatal elevation of endocannabinoids corrects the unbalance between dopamine systems and reduces activity in the Naples High Excitability rats.

Several evidences suggest that endocannabinoids exert a neurotrophic effect on developing mesencephalic dopamine neurons. Since an altered mesocorticolimbic system seems to underlie hyperactivity and attention deficit in clinical and animal studies of attention deficit hyperactivity disorder (ADHD), prenatal elevation of anandamide has been induced in Naples high excitability (NHE) rats by inhibition of its reuptake. To this aim, pregnant NHE and random-bred females received a subcutaneous injection of AM-404 (1 mg/kg) or vehicle daily from E11 until E20. Young adult male offsprings were exposed to a spatial novelty (Làt-maze) for 30 min and the behavior was videotaped and analysed for indices of activity (travelled distance, rearing frequency) and attention (rearing duration). Moreover, morphological analysis of the brains was carried out that pertained to cytochrome oxydase as marker of metabolic activity and thyrosine hydroxylase as marker of the dopamine systems. The results indicate that prenatal AM-404 treatment significantly reduces activity by about 20% during the entire testing period and modifies the distribution of scanning times towards short duration episodes in the first part of the test only in NHE-treated rats. In addition, image analysis revealed a significant increase in relative optical density of TH+terminals in the dorsal striatum and substantia nigra of AM-404 treated NHE rats and minor changes in the dorsal cortex of AM-404 treated NRB rats. The data suggest a corrected unbalance between the two dopamine systems that apparently leads to reduced hyperactivity and modified scanning times in this animal model of ADHD. This, in turn, might open new strategies in the treatment of a subset of ADHD cases.

Butyrate downregulates alpha2beta1 integrin: a possible role in the induction of apoptosis in colorectal cancer cell lines.

BACKGROUND: Integrins mediate cell matrix adhesion and regulate cell growth and survival. In colonic epithelial cells, alpha(2)beta(1) integrin controls glandular differentiation and proliferation. Butyrate stimulates differentiation and induces apoptosis in vitro. AIMS: We investigated whether butyrate induction of apoptosis was associated with perturbation of integrin mediated cell matrix adhesion. METHODS: Three colonic cancer cell lines (SW1222, SW620, LS174T) were studied. Adhesion to extracellular matrix proteins, expression of alpha(2)beta(1) integrin, and apoptosis were studied in adherent cells after treatment with 4 mM butyrate. RESULTS: Butyrate decreased the attachment to type I collagen in SW620 cells and type I and IV collagen in LS174T cells. The decreased cell attachment was associated with downregulation of alpha(2)beta(1) integrin and increased apoptosis in adherent cells. No changes in alpha(2)beta(1) expression or matrix adhesion were seen in SW1222 cells, which were also found to be less sensitive to butyrate induction of apoptosis. Downregulation of alpha(2)beta(1) integrin preceded the detection of apoptosis. CONCLUSION: Apoptosis induced by butyrate is associated with downregulation of expression and functional activity of alpha(2)beta(1) integrin. Perturbation of cell matrix adhesion may be a novel mechanism by which butyrate induces apoptosis in colorectal cancer cells.

Abnormal alpha-catenin expression in invasive breast cancer correlates with poor patient survival.

AIMS: alpha-Catenin is a member of the E-cadherin-catenin family of adhesion molecules whose role is essential for the function of the E-cadherin complex. In this study, we have evaluated the expression of alpha-catenin but also of the other catenins (beta-, gamma- and p120-catenin) and E-cadherin in invasive breast cancer and statistically analysed these expressions with known clinicopathological parameters, c-erbB-2 oncoprotein expression and patient survival. METHODS AND RESULTS: Abnormal E-cadherin and beta-catenin expression, especially loss of expression, was associated with lobular histological type of breast carcinomas (P=0.03 and P=0.01, respectively). Abnormal E-cadherin and alpha-catenin expression was associated with high histological grade ductal carcinomas (P=0.01 and P=0.03, respectively). Abnormal E-cadherin and beta-catenin expression was correlated with lymph node metastases (P=0.02 and P=0.05, respectively), while abnormal alpha- and beta-catenin were correlated with the advanced stage of the disease (P=0.04 and P=0.05, respectively). Abnormal p120-catenin expression was associated with loss of PR (P=0.008). Survival analysis demonstrated a statistically significant association between abnormal alpha-catenin expression and poor patient survival (P=0.02). When survival analysis was performed according to the different patterns of abnormal expression, statistically significant associations were seen between cytoplasmic alpha- and beta-catenin expression and poor survival (P=0.006 and P=0.04, respectively). CONCLUSIONS: alpha-Catenin, especially its cytoplasmic expression, seems to be a more sensitive prognostic marker than the other members of the E-cadherin complex in invasive breast cancer.

Molecular histology in the study of solid tumours.

Dominant oncogenes and tumour suppressor gene abnormalities are crucial events in human cancer. Many molecular techniques are used to identify these abnormalities, including single strand conformational polymorphism, the polymerase chain reaction, cloning, and sequencing, although the biological relevance of these changes is not always apparent. Immuno-histochemistry (ICH) or western blotting of abnormal gene products can provide information about their cellular localisation and expression in neoplastic versus normal cells, and can sometimes give a clue to their function. For example, ICH has shown how loss of the intercellular adhesion molecule E-cadherin, or abnormal localisation from the cell membrane to the cytoplasm, correlates with a diffuse tumour phenotype and a less favourable clinical outcome. Similarly, ICH of beta-catenin (a protein that binds E-cadherin and is essential for its function) has shown abnormal cellular localisation in the nucleus in a variety of human malignancies; in particular, colorectal carcinomas, where abnormal forms of the adenomatous polyposis coli gene product cause nuclear and cytoplasmic sequestration of beta-catenin. Such studies show how morphological assessment can sometimes provide insight into molecular function and dysfunction in human malignancy.

Environmental factors during postnatal period modify activity and non-selective attention in the Naples High-Excitability rat.

The involvement of epigenetic factors in the phenotypic expression of the neural systems underlying activity and attentive processes has been investigated in an animal model of hyperactivity and attention-deficit, the Naples High-Excitability rat (NHE). To this aim, male NHE pups have been reared in small (four) or normal litter size (nine) during the first 4 weeks of postnatal life. Both groups underwent a differential handling procedure occurring once, twice or four times a week. After weaning (28 days), rats were housed in groups of two and tested as young adults for activity and non-selective attention in a spatial novelty situation for three consecutive tests at 24-h intervals. The behaviour was videotaped and analysed off line for the frequency of corner crossings and rearings and duration of rearings. The results indicate that the increased maternal care and high fat diet induced by the small litter size produced long lasting effects on activity and duration of rearing episodes that indexes non-selective attention. These effects were complex as differential handling was beneficial only at low stimulation level. Thus, these findings suggest that epigenetic factors acting during critical periods of post-natal development may interact with genetic determinants that in turn influence the maturation of the neural systems controlling activity, orienting and scanning time.

Selective inhibition of neuronal nitric oxide synthesis reduces hyperactivity and increases non-selective attention in the Naples High-Excitability rat.

The involvement of neuron-derived NO in the process of orienting and scanning times (non-selective attention: NSA) towards environmental stimuli has been investigated in the Naples High-Excitability rat (NHE), a putative animal model of Hyperactivity and Attention Deficit (ADHD). To this aim, orienting and scanning times have been monitored by the frequency and duration of rearing episodes, respectively. Adult male NHE rats were tested in a novelty situation (Làt-maze) for 30 min following single or repeated injections of the non competitive inhibitor 7-Nitroindazole (7-NINA) of the neuronal isoform of the enzyme nitric oxide synthase (n-NOS). In the acute experiments, rats received a single injection of 7-NINA (1 mg/kg) intraperitonealy in a saline vehicle (exp. 1, fast release) or subcutaneously in a lipid carrier, dimethyl sulfoxide (DMSO; exp. 2, slow release) or the vehicles alone as controls 30 min before testing. In the repeated injection experiments, rats received a subcutaneus injection of 1 mg/kg in DMSO or DMSO alone daily for 14 days, and tested 24 h after the last injection (exp. 3, slow release). The results showed a significant differential effect of the drug that was dependent on the release rate, i.p. saline-diluted 7-NINA increased the duration of individual rearing episodes whereas, both single and repeated subcutaneous DMSO-carried 7-NINA exerted an opposite effect. Thus, selective inhibition of n-NOS by an allosteric inhibitor that increases arginine availability without displacing the inhibitor from n-NOS, strengthens the hypothesized role of NO in NSA. These findings may shed light on the mechanism of action of drug treatment of and be useful in the treatment of ADHD in children.