Forest resilience to global warming is strongly modulated by local-scale topographic, microclimatic and biotic conditions

Resilience of endangered rear edge populations of cold-adapted forests in the Mediterranean basin is increasingly altered by extreme heatwave and drought pressures. It remains unknown, however, whether microclimatic variation in these isolated forests could ultimately result in large intra-population variability in the demographic responses, allowing the coexistence of contrasting declining and resilient trends across small topographic gradients. Multiple key drivers promoting spatial variability in the resilience of rear edge forests remain largely unassessed, including amplified and buffered thermal exposure induced by heatwaves along topographic gradients, and increased herbivory pressure on tree saplings in defaunated areas lacking efficient apex predators. Here we analysed whether indicators of forest resilience to global warming are strongly modulated by local-scale topographic, microclimatic and biotic conditions. We studied a protected rear edge forest of sessile oak Quercus petraea, applying a suite of 20 indicators of resilience of tree secondary growth, including multidecadal and short-term indices. We also analysed sapling recruitment success, recruit/adult ratios and sapling thermal exposure across topographic gradients. We found large within population variation in secondary growth resilience, in recruitment success and in thermal exposure of tree saplings to heatwaves, and this variability was spatially structured along small-scale topographical gradients. Multidecadal resilience indices and curves provide useful descriptors of forest vulnerability to climate warming, complementing assessments based in the analysis of short-term resilience indicators. Species-specific associations of trees with microclimatic variability are reported. Biotic factors are key in determining long-term resilience in climatically stressed rear edge forests, with strong limitation of sapling recruitment by increased roe deer and wild boar herbivory. Our results also support non-stationary effects of climate determining forest growth responses and resilience, showing increased negative effects of warming and drought over the last decades in declining stands. Synthesis. Our findings do not support scenarios predicting spatially homogeneous distributional shifts and limited resilience in rear edge populations, and are more supportive of scenarios including spatially heterogeneous responses, characterised with contrasting intra-population trends of forest resilience. We conclude that forest resilience responses to climate warming are strongly modulated by local-scale microclimatic, topographic and biotic factors. Accurate predictions of forest responses to changes in climate would therefore largely benefit from the integration of local-scale abiotic and biotic factors

Cellular distribution of the histamine H3 receptor in the basal ganglia : functional modulation of dopamine and glutamate neurotransmission

This is the author's version of a work that was accepted for publication in Basal ganglia. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Vol. 3 Núm. 2 (Jul. 2013)Altres ajuts: Red_de_Trastornos_Adictivos/RD06/0001/0015Histamine H3 receptors (H3R) are widely expressed in the brain where they participate in sleep-wake cycle and cognition among other functions. Despite their high expression in some regions of the basal ganglia, their functional role in this forebrain neural network remains unclear. The present findings provide in situ hybridization and immunohistochemical evidence for H3R expression in several neuronal populations of the rat basal ganglia but not in astrocytes (glial fibrillary acidic protein immunoreactive cells). We demonstrate the presence of H3R mRNA and protein in dopaminergic neurons (tyrosine hydroxylase positive) of the ventral tegmental area and substantia nigra. In the dorsal and ventral (nucleus accumbens) striatal complex we show H3R immunoreactivity in cholinergic (choline acetyltransferase immunoreactive) and GABAergic neurons (substance P, proenkephalin or dopamine D1 receptor positive) as well as in corticostriatal terminals (VGLUT1-immunoreactive). Double-labelling experiments in the medial prefrontal cortex show that H3R is expressed in D1R-positive interneurons and VGLUT1-positive corticostriatal output neurons. Our functional experiments confirm that H3R ligands modulate dopamine synthesis and the probability of glutamate release in the striatum from cortico-striatal afferents. The presence of H3R in such different neuronal populations and its involvement in the control of striatal dopaminergic and glutamatergic transmission ascribes a complex role to H3R in the function of the basal ganglia neural network

Spontaneous changes in brain striatal dopamine synthesis and storage dynamics ex vivo reveal end-product feedback-inhibition of tyrosine hydroxylase

Altres ajuts: acord transformatiu CRUE-CSICAltres ajuts: , The Michael J. Fox Foundation (ID15291), "la Caixa" Foundation (ID 100010434), under the agreement LCF/PR/HR17/52150003Synaptic events are important to define treatment strategies for brain disorders. In the present paper, freshly obtained rat brain striatal minces were incubated under different times and conditions to determine dopamine biosynthesis, storage, and tyrosine hydroxylase phosphorylation. Remarkably, we found that endogenous dopamine spontaneously accumulated during tissue incubation at 37 °C ex vivo while dopamine synthesis simultaneously decreased. We analyzed whether these changes in brain dopamine biosynthesis and storage were linked to dopamine feedback inhibition of its synthesis-limiting enzyme tyrosine hydroxylase. The aromatic-l-amino-acid decarboxylase inhibitor NSD-1015 prevented both effects. As expected, dopamine accumulation was increased with l-DOPA addition or VMAT2-overexpression, and dopamine synthesis decreased further with added dopamine, the VMAT2 inhibitor tetrabenazine or D2 auto-receptor activation with quinpirole, accordingly to the known synaptic effects of these treatments. Phosphorylation activation and inhibition of tyrosine hydroxylase on Ser31 and Ser40 with okadaic acid, Sp-cAMP and PD98059 also exerted the expected effects. However, no clear-cut association was found between dopamine feedback inhibition of its own biosynthesis and changes of tyrosine hydroxylase phosphorylation, assessed by Western blot and mass spectrometry. The later technique also revealed a new Thr30 phosphorylation in rat tyrosine hydroxylase. Our methodological assessment of brain dopamine synthesis and storage dynamics ex vivo could be applied to predict the in vivo effects of pharmacological interventions in animal models of dopamine-related disorders

Paper del receptor H3 d’histamina en la neurotransmissió dopaminèrgica i el desig d’autoadministració de cocaïna.

El nostre grup ha desenvolupat una tècnica directa per a la determinació radioisotòpica de la síntesi i l’alliberament de DA en cervell de rata. Les mostres s’incuben amb 3H-Tirosina i la 3H-Dopamina que es forma en el teixit és purificada posteriorment per HPLC. La determinació simultània amb la nostra tècnica de la síntesi i l’alliberament de dopamina fa que sigui una solució versàtil i permeti un processament de gran quantitat de mostres de manera automatitzada utilitzant el HPLC. Actualment la dependència a la cocaïna no té tractament farmacològic. S’utilitzen com a model animals de recaiguda per a la cerca de nous medicaments. El receptor H3 de histamina és relativament abundant en el cervell respecte altres teixits i en particular el nucli accumbens i l’estriat. Estudis previs suggereixen que l’antagonista/agonista invers del receptor H3 facilita l’alliberament de dopamina reforçant els efectes subjectius dels psicoestimulants. El nostre grup ha demostrat que l’agonista del receptor H3 d’ histamina disminueix la cerca de cocaïna en un test d’extinció i recaiguda en un model animal d’autoadministració. El pretractament del agonista H3 d’histamina disminueix la resposta en una prova d’extinció i recaiguda.We have developed a straightforward radioisotopic determination of dopamine synthesis in brain striatal tissue preparations. Brain miniprisms are incubated with 3H-tyrosine, and 3H-dopamine formed is purified by HPLC. We tested our method with prototypical stimulators (dbcAMP, okadaic acid) and inhibitors (3-I-tyrosine, GABA) of tyrosine hydroxylase activity as well as with dopamine D2 autoreceptor agonists. Dopamine release to the incubation buffer was simultaneously determined in some experiments in order to better characterize dopaminergic neuronal mechanisms. We tested our method on determinations of 3H-dopamine release after K+ depolarization, inhibition of dopamine uptake or metabolism. Effects of psychotropic drugs nicotine and cocaine are also described. Cocaine dependence has no pharmacological treatment. Relapse models in animals are used as a screen for new medications. Histamine H3 receptors are relatively abundant in brain respect to other tissues, and particularly in the nucleus accumbens and striatum. Previous studies suggest that H3 antagonists/inverse agonists could facilitate dopamine release, reinforcement and/or the subjective effects of psychostimulants. Here we show that histamine H3 receptor agonists decrease cocaine seeking in tests of extinction and reinstatement of cocaine self-administration. Rats were subjected to cocaine self-administration under a FR5 schedule, followed by a reinforcement dose-response, progressive ratio, extinction and reinstatement tests elicited by two doses of cocaine priming

Paper del receptor H₃ d'histamina en la neurotransmissió dopaminèrgica i el desig d'autoadministració de cocaïna

El nostre grup ha desenvolupat una tècnica directa per a la determinació radioisotòpica de la síntesi i l'alliberament de DA en cervell de rata. Les mostres s'incuben amb 3H-Tirosina i la 3H-Dopamina que es forma en el teixit és purificada posteriorment per HPLC. La determinació simultània amb la nostra tècnica de la síntesi i l'alliberament de dopamina fa que sigui una solució versàtil i permeti un processament de gran quantitat de mostres de manera automatitzada utilitzant el HPLC. Actualment la dependència a la cocaïna no té tractament farmacològic. S'utilitzen com a model animals de recaiguda per a la cerca de nous medicaments. El receptor H3 de histamina és relativament abundant en el cervell respecte altres teixits i en particular el nucli accumbens i l'estriat. Estudis previs suggereixen que l'antagonista/agonista invers del receptor H3 facilita l'alliberament de dopamina reforçant els efectes subjectius dels psicoestimulants. El nostre grup ha demostrat que l'agonista del receptor H3 d' histamina disminueix la cerca de cocaïna en un test d'extinció i recaiguda en un model animal d'autoadministració. El pretractament del agonista H3 d'histamina disminueix la resposta en una prova d'extinció i recaigudaWe have developed a straightforward radioisotopic determination of dopamine synthesis in brain striatal tissue preparations. Brain miniprisms are incubated with 3H-tyrosine, and 3H-dopamine formed is purified by HPLC. We tested our method with prototypical stimulators (dbcAMP, okadaic acid) and inhibitors (3-I-tyrosine, GABA) of tyrosine hydroxylase activity as well as with dopamine D2 autoreceptor agonists. Dopamine release to the incubation buffer was simultaneously determined in some experiments in order to better characterize dopaminergic neuronal mechanisms. We tested our method on determinations of 3H-dopamine release after K+ depolarization, inhibition of dopamine uptake or metabolism. Effects of psychotropic drugs nicotine and cocaine are also described. Cocaine dependence has no pharmacological treatment. Relapse models in animals are used as a screen for new medications. Histamine H3 receptors are relatively abundant in brain respect to other tissues, and particularly in the nucleus accumbens and striatum. Previous studies suggest that H3 antagonists/inverse agonists could facilitate dopamine release, reinforcement and/or the subjective effects of psychostimulants. Here we show that histamine H3 receptor agonists decrease cocaine seeking in tests of extinction and reinstatement of cocaine self-administration. Rats were subjected to cocaine self-administration under a FR5 schedule, followed by a reinforcement dose-response, progressive ratio, extinction and reinstatement tests elicited by two doses of cocaine priming

Snail1 is required for the maintenance of the pancreatic acinar phenotype

The Snail1 transcriptional factor is required for correct embryonic development, yet its expression in adult animals is very limited and its functional roles are not evident. We have now conditionally inactivated Snail1 in adult mice and analyzed the phenotype of these animals. Snail1 ablation rapidly altered pancreas structure: one month after Snail1 depletion, acinar cells were markedly depleted, and pancreas accumulated adipose tissue. Snail1 expression was not detected in the epithelium but was in pancreatic mesenchymal cells (PMCs). Snail1 ablation in cultured PMCs downregulated the expression of several β-catenin/Tcf-4 target genes, modified the secretome of these cells and decreased their ability to maintain acinar markers in cultured pancreas cells. Finally, Snail1 deficiency modified the phenotype of pancreatic tumors generated in transgenic mice expressing c-myc under the control of the elastase promoter. Specifically, Snail1 depletion did not significantly alter the size of the tumors but accelerated acinar-ductal metaplasia. These results demonstrate that Snail1 is expressed in PMCs and plays a pivotal role in maintaining acinar cells within the pancreas in normal and pathological conditions

Cellular distribution of the histamine H3 receptor in the basal ganglia : functional modulation of dopamine and glutamate neurotransmission

This is the author's version of a work that was accepted for publication in Basal ganglia. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Vol. 3 Núm. 2 (Jul. 2013)Histamine H3 receptors (H3R) are widely expressed in the brain where they participate in sleep-wake cycle and cognition among other functions. Despite their high expression in some regions of the basal ganglia, their functional role in this forebrain neural network remains unclear. The present findings provide in situ hybridization and immunohistochemical evidence for H3R expression in several neuronal populations of the rat basal ganglia but not in astrocytes (glial fibrillary acidic protein immunoreactive cells). We demonstrate the presence of H3R mRNA and protein in dopaminergic neurons (tyrosine hydroxylase positive) of the ventral tegmental area and substantia nigra. In the dorsal and ventral (nucleus accumbens) striatal complex we show H3R immunoreactivity in cholinergic (choline acetyltransferase immunoreactive) and GABAergic neurons (substance P, proenkephalin or dopamine D1 receptor positive) as well as in corticostriatal terminals (VGLUT1-immunoreactive). Double-labelling experiments in the medial prefrontal cortex show that H3R is expressed in D1R-positive interneurons and VGLUT1-positive corticostriatal output neurons. Our functional experiments confirm that H3R ligands modulate dopamine synthesis and the probability of glutamate release in the striatum from cortico-striatal afferents. The presence of H3R in such different neuronal populations and its involvement in the control of striatal dopaminergic and glutamatergic transmission ascribes a complex role to H3R in the function of the basal ganglia neural network

Cocaine disrupts histamine H3 receptor modulation of dopamine D1 receptor signaling: σ1-D1-H3 receptor complexes as key targets for reducing cocaine’s effects

The general effects of cocaine are not well understood at the molecular level. What is known is that dopamine D1 receptor plays an important role. Here we show that a key mechanism may be cocaine’s blockade of the histamine H3 receptor-mediated inhibition of D1 receptor function. This blockade requires the σ1 receptor and occurs upon cocaine binding to σ1-D1-H3 receptor complexes. The cocaine-mediated disruption leaves an uninhibited D1 receptor that activates Gs, freely recruits β-arrestin, increases p-ERK 1/2 levels and induces cell death when over activated. Using in vitro assays with transfected cells and in ex vivo experiments using both rats acutely treated or self-administered with cocaine along with mice depleted of σ1 receptor, we show that blockade of σ1 receptor by an antagonist restores the protective H3 receptor-mediated brake on D1 receptor signaling and prevents the cell death from elevated D1 receptor signaling. These findings suggest that a combination therapy of σ1R antagonists with H3 receptor agonists could serve to reduce some effects of cocaine