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α-Conotoxins are disulfide-rich peptides that target nicotinic acetylcholine receptors. Recently we identified several α-conotoxins that also modulate voltage-gated calcium channels by acting as G protein-coupled GABAB receptor (GABABR) agonists. These α-conotoxins are promising drug leads for the treatment of chronic pain. To elucidate the diversity of α-conotoxins that act through this mechanism, we synthesized and characterized a set of peptides with homology to α-conotoxins known to inhibit high voltage-activated calcium channels via GABABR activation. Remarkably, all disulfide isomers of the active α-conotoxins Pu1.2 and Pn1.2, and the previously studied Vc1.1 showed similar levels of biological activity. Structure determination by NMR spectroscopy helped us identify a simplified biologically active eight residue peptide motif containing a single disulfide bond that is an excellent lead molecule for developing a new generation of analgesic peptide drugs. [ABSTRACT FROM AUTHOR]

Objective The gut is a major site of contact between immune and sensory systems and evidence suggests that patients with irritable bowel syndrome (IBS) have immune dysfunction. Here we show how this dysfunction differs between major IBS subgroups and how immunocytes communicate with sensory nerves. Design Peripheral blood mononuclear cell supernatants from 20 diarrhoea predominant IBS (D-IBS) patients, 15 constipation predominant IBS (C-IBS) patients and 36 healthy subjects were applied to mouse colonic sensory nerves and effects on mechanosensitivity assessed. Cytokine/chemokine concentration in the supernatants was assessed by proteomic analysis and correlated with abdominal symptoms, and expression of cytokine receptors evaluated in colonic dorsal root ganglia neurons. We then determined the effects of specific cytokines on colonic afferents. Results D-IBS supernatants caused mechanical hypersensitivity of mouse colonic afferent endings, which was reduced by infliximab. C-IBS supernatants did not, but occasionally elevated basal discharge. Supernatants of healthy subjects inhibited afferent mechanosensitivity via an opioidergic mechanism. Several cytokines were elevated in IBS supernatants, and levels correlated with pain frequency and intensity in patients. Visceral afferents expressed receptors for four cytokines: IL-1ß, IL-6, IL-10 and TNF-a. TNF-a most effectively caused mechanical hypersensitivity which was blocked by a transient receptor potential channel TRPA1 antagonist. IL-1ß elevated basal firing, and this was lost after tetrodotoxin blockade of sodium channels. Conclusions Distinct patterns of immune dysfunction and interaction with sensory pathways occur in different patient groups and through different intracellular pathways. Our results indicate IBS patient subgroups would benefit from selective targeting of the immune system. [ABSTRACT FROM AUTHOR]

Visceral pain following infection or inflammation is a major clinical problem. Although we have knowledge of how peripheral endings of colonic afferents change in disease, their central projections have been overlooked. With neuroanatomical tracing and colorectal distension (CRD), we sought to identify colonic afferent central terminals (CACTs), the dorsal horn (DH) neurons activated by colonic stimuli in the thoracolumbar (T10-L1) DH, and determine how they are altered by postinflammatory chronic colonic mechanical hypersensitivity. Retrograde tracing from the colon identified CACTs in the DH, whereas immunohistochemistry for phosphorylated MAP kinase ERK 1/2 (pERK) identified DH neurons activated by CRD (80 mmHg). In healthy mice, CACTs were located primarily in DH laminae I (LI) and V (LV) and projected down middle and lateral DH collateral pathways. CRD evoked pERK immunoreactivity in DH neurons, the majority of which were located in LI and LV, the same regions as CACTs. In postinflammatory mice, CACTs were significantly increased in T12-L1 compared with healthy mice. Although CACTs remained abundant in LI, they were more widespread and were now present in deeper laminae. After CRD, significantly more DH neurons were pERK-IR postinflammation (T12-L1), with abundant expression in LI and deeper laminae. In both healthy and postinflammatory mice, many pERK neurons were in close apposition to CACTs, suggesting that colonic afferents can stimulate specific DH neurons in response to noxious CRD. Overall, we demonstrate that CACT density and the number of responsive DH neurons in the spinal cord increase postinflammation, which may facilitate aberrant central representation of colonic nociceptive signaling following chronic peripheral hypersensitivity. J. Comp. Neurol. 520:2241-2255, 2012. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

With the aim of contributing to the knowledge of the country's natural ecosystems, the edaphic characteristics and the floristic composition of the seasonally dry forest, (La Menta, 04º 43' 55" LS and 80º 04' 55" LO, province of Piura; and Timbes, 04º 44' 58" LS and 80º 03' 33" LO, province of Ayabaca), both in the Piura Region, Peru, were determined. The study area covers an approximate area of 6 000 hectares and has an altitude of 350 to 1 350 m.a.s.l. In each forest 5 transects of 10 x 50 m at intervals of 20 m, were sampled, making a total of 2 500 m². Soil analysis showed low levels in organic matter, nitrogen and potassium and assimilable phosphorus media. These soils have been classified in the Entisols order and Orthents suborder. At La Menta forest 18 species were registered, among trees and shrubs with at breast height diameter s ≥ 1.0 cm, totaling a number of 162 individuals, whilst at Timbes forest 23 species were registered, with a total of 190 individuals. The basal area times total assessed area was 128.86 m2 for La Menta, where Loxopterigyum huasango with 45.97 m² was highlighted. For Timbes it was 196.63 m², where Erythrina smithiana with 47.13 m² was highlighted. The importance value index, above a value of 300.0 was 50.0% for Bursera graveolens at La Menta and 62.0% for Cordia lutea at Timbes. The Diversity Index of Shannon-Wiener showed that the La Menta forest was of greater value than the Timbes forest, even though it had the lowest numbers of species and the Matrix of Bray and Curtis Similarity showed that the two forests had a similarity of 54.68%. [ABSTRACT FROM AUTHOR]

The article discusses the findings of a study which determined the effect of TRPA1 protein in detecting mechanical stimuli in pain sensing neurons. The experiment noted the presence of TRPA1 transcript, protein, and functional expression in smaller-diameter neurons, and the recording of mechanically activated currents termed intermediately (IAMC), rapidly (RAMC), and slowly (SAMC). The study was able to demonstrate the contribution of TRPA1 to normal mechanosensation for a set of dorsal root ganglion (DRG) neurons.

1. Oscillatory increases in the cytoplasmic Ca2+ concentration ([Ca2+]cyt) play essential roles in the hormonal regulation of liver cells. Increases in [Ca2+]cyt require Ca2+ release from the endoplasmic reticulum (ER) and Ca2+ entry across the plasma membrane. 2. Store-operated Ca2+ channels (SOCs), activated by a decrease in Ca2+ in the ER lumen, are responsible for maintaining adequate ER Ca2+. Experiments using patch-clamp recording and the fluorescent Ca2+ reporter fura-2 indicate there is only one type of SOC in rat liver cells. These SOCs have a high selectivity for Ca2+ and properties essentially indistinguishable from those of Ca2+ release-activated Ca2+ (CRAC) channels. 3. Although Orai1, a CRAC channel pore protein, and stromal interaction molecule 1 (STIM1), a CRAC channel Ca2+ sensor, are components of liver cell SOCs, the mechanism of activation of SOCs, and in particular the role of subregions of the ER, are not well understood. 4. Recent experiments have used the transient receptor potential vanilloid 1 (TRPV1) non-selective cation channel, ectopically expressed in liver cells, and a choleretic bile acid to deplete Ca2+ from different ER subregions. The results of these studies have provided evidence that only a small component of the ER is required for STIM1 redistribution and the activation of SOCs. 5. It is concluded that different Ca2+ microdomains in the ER and cytoplasmic space are important in both the activation of SOCs and in the signalling actions of Ca2+ in liver cells. Future experiments will investigate the nature of these microdomains further. [ABSTRACT FROM AUTHOR]

Abstract: Cholestasis is a significant contributor to liver pathology and can lead to primary sclerosis and liver failure. Cholestatic bile acids induce apoptosis and necrosis in hepatocytes but these effects can be partially alleviated by the pharmacological application of choleretic bile acids. These actions of bile acids on hepatocytes require changes in the release of Ca2+ from intracellular stores and in Ca2+ entry. However, the nature of the Ca2+ entry pathway affected is not known. We show here using whole cell patch clamp experiments with H4-IIE liver cells that taurodeoxycholic acid (TDCA) and other choleretic bile acids reversibly activate an inwardly-rectifying current with characteristics similar to those of store-operated Ca2+ channels (SOCs), while lithocholic acid (LCA) and other cholestatic bile acids inhibit SOCs. The activation of Ca2+ entry was observed upon direct addition of the bile acid to the incubation medium, whereas the inhibition of SOCs required a 12 h pre-incubation. In cells loaded with fura-2, choleretic bile acids activated a Gd3+-inhibitable Ca2+ entry, while cholestatic bile acids inhibited the release of Ca2+ from intracellular stores and Ca2+ entry induced by 2,5-di-(tert-butyl)-1,4-benzohydro-quinone (DBHQ). TDCA and LCA each caused a reversible redistribution of stromal interaction molecule 1 (STIM1, the endoplasmic reticulum Ca2+ sensor required for the activation of Ca2+ release-activated Ca2+ channels and some other SOCs) to puncta, similar to that induced by thapsigargin. Knockdown of Stim1 using siRNA caused substantial inhibition of Ca2+-entry activated by choleretic bile acids. It is concluded that choleretic and cholestatic bile acids activate and inhibit, respectively, the previously well-characterised Ca2+-selective hepatocyte SOCs through mechanisms which involve the bile acid-induced redistribution of STIM1. [Copyright &y& Elsevier]

The effect of osmotic stress on sugar transport was investigated in Clone 9 epithelial cells, which express the glucose uniporter GLUT1, and in 3T3-L1 adipocytes, which express both GLUT1 and GLUT4. An acute hyperosmotic shock increased the uptake of sugars in both cell types. In Clone 9 cells, this was followed by a regulatory volume increase (RVI) response. Stimulation of transport was rapid and reversible, with half-lives (t1/2) for stimulation of 2-deoxy-D-glucose uptake of 5.6±0.9 (n=6) and 22.7±1.5 (n=4) min for Clone 9 cells and adipocytes respectively. The effect was dose dependent, reaching a maximum at 1.1 osM of 2.9±0.1-fold (n=3) for Clone 9 cells and 8.2±0.8-fold (n=3) for adipocytes. In the latter, this stimulation correlated with translocation of the glucose transporter isoform GLUT4 to the cell surface and was not significantly different from that elicited by 160 nM insulin (7.6±1.2-fold, n=3). The effect of osmotic shock was not, however, influenced by inhibitors of either phosphoinositide 3-kinase (PI 3-kinase) (wortmannin, 250 nM) or of p38 mitogen-activated protein kinase (p38 MAP kinase) (SB203580, 20 µM), which reportedly prevent GLUT4 translocation and/or activation by insulin respectively. These inhibitors also had no effect on the stimulation of transport by osmotic shock in Clone 9 cells. However, in contrast to adipocytes, the effect of osmotic shock on glucose transport in Clone 9 cells reflected primarily a change in the intrinsic activity of cell surface transporters and there was only a minor change in their subcellular distribution as assessed by cell immunostaining or no change as assessed by surface biotinylation. These results indicate that the response of cells to osmotic shock can involve changes both in transporter activity and location. The signal transduction pathways involved include neither PI 3-kinase nor the classical, osmotically-activated component, p38 MAP kinase. [ABSTRACT FROM AUTHOR]

A survey of 209 Chimane Amerindian households in 18 villages in the Bolivian rainforest was done to examine the role of tenure security and private time preference on the clearance of old-growth forest. Results of Tobit regressions suggest that conflict with abutters was associated with more deforestation, but the average impatience of the household heads was associated with less deforestation. Results suggest that governments should protect the land rights of indigenous people if they wish to enhance conservation. Results cast doubts on the idea that high private time preference increases the depletion of natural resources. [ABSTRACT FROM AUTHOR]

Our understanding of how abdominal organs (like the gut) communicate with the brain, via sensory nerves, has been limited by a lack of techniques to selectively activate or inhibit populations of spinal primary afferent neurons within dorsal root ganglia (DRG), of live animals. We report a survival surgery technique in mice, where select DRG are surgically removed (unilaterally or bilaterally), without interfering with other sensory or motor nerves. Using this approach, pain responses evoked by rectal distension were abolished by bilateral lumbosacral L5-S1 DRG removal, but not thoracolumbar T13-L1 DRG removal. However, animals lacking T13-L1 or L5-S1 DRG both showed reduced pain sensitivity to distal colonic distension. Removal of DRG led to selective loss of peripheral CGRP-expressing spinal afferent axons innervating visceral organs, arising from discrete spinal segments. This method thus allows spinal segment-specific determination of sensory pathway functions in conscious, free-to-move animals, without genetic modification. A surgical method in mice can selectively remove dorsal root ganglia (DRG) at specific spinal levels without interfering with other nerves, providing insight on thoracolumbar vs. lumbosacral DRG contributions to pain signalling and behaviour. [ABSTRACT FROM AUTHOR]