Rapid Non-genomic Mechanisms Research Articles

Unipolar and Bipolar Depressed Inpatients: correlations with Vitamin D and Cognitive Symptoms

Introduction Cognitive symptoms are the main factor of discomfort in depressed patients, persisting even during clinical remission (Conradi et al. Psychol Med 2011;41:1165-74) and inevitably compromising their quality of life (Fehnel et al. CNS Spectr 2013;25:1-10). Several studies have suggested the neuroprotective role of vitamin D, both through actions on the genome and rapid non-genomic mechanisms; so, low serum vitamin D levels are related to poorer cognitive performance (Goodwill et al. JAGS 2017;2:1-8), depressive disorders (Kjærgaard et al. Psyc Res 2011;190:221-225) and suicide risk (Umhau et al. PLoS One 2013;8:e51543).Objectivesto investigate relationships between serum vitamin D levels, depressive symptoms and cognitive performance in unipolar and bipolar depressed adults hospitalized for Major Depressive Episode (MDE).Methods80 patients (34 M and 46 F; average age 48,96±14,17 years; 40% with bipolar depression) were examined. Depression was investigated using Hamilton Rating Scale for Depression (HAM-D), while cognitive functions were explored by: Rey Auditory Verbal Learning Test (RAVLT) and Rey-Osterrieth Complex Figure (ROCF) to assess verbal and visuospatial memory, respectively; Trail Making Test (TMT) and Stroop Color and Word Test to assess attention, spatial planning and cognitive flexibility. Venous blood sampling was used to determine serum Vitamin D levels (average level 15,67 ± 8,7 ng/ml).Results At first, the serum level of vitamin D was found to be inversely correlated with HAM-D scores (p=0,0079), so that lower concentrations of vitamin D is related to greater severity of depression. In addiction, there were strongly significative positive correlations between low vitamin D levels and poorer RAVLT and ROCF scores and strongly significative negative correlations between vitamin serum level and higher scores in TMT and STROOP test, so that calcidiol deficit is associated with poor cognitive performance. Similarly, patients with higher HAM-D scores were found to have a greater cognitive impairment (lower RAVLT e ROCF scores and higher TMT e STROOP scores).Conclusions In accordance with previous works, our study supports the close relationship between serum vitamin D levels and depressive morbidity. During MDE hypovitaminosis D is related to worse disease indices, such as severity of affective symptoms and cognitive impairment, without substantial differences between clinical manifestations of unipolar and bipolar depression, both in terms of affective and cognitive symptoms and disease severity. Considering that cognitive deficits are truly disabling because they may resist to common antidepressant treatments and, as a result, persist during stages of clinical remission, vitamin d supplementation, by minimizing cognitive dysfunction, could be a good strategy to reduce the risk of relapses and to improve patients’ functioning and quality of life.Disclosure of InterestNone Declared

Epigenetic embedding of childhood adversity: mitochondrial metabolism and neurobiology of stress-related CNS diseases.

This invited article ad memoriam of Bruce McEwen discusses emerging epigenetic mechanisms underlying the long and winding road from adverse childhood experiences to adult physiology and brain functions. The conceptual framework that we pursue suggest multidimensional biological pathways for the rapid regulation of neuroplasticity that utilize rapid non-genomic mechanisms of epigenetic programming of gene expression and modulation of metabolic function via mitochondrial metabolism. The current article also highlights how applying computational tools can foster the translation of basic neuroscience discoveries for the development of novel treatment models for mental illnesses, such as depression to slow the clinical manifestation of Alzheimer's disease. Citing an expression that many of us heard from Bruce, while "It is not possible to roll back the clock," deeper understanding of the biological pathways and mechanisms through which stress produces a lifelong vulnerability to altered mitochondrial metabolism can provide a path for compensatory neuroplasticity. The newest findings emerging from this mechanistic framework are among the latest topics we had the good fortune to discuss with Bruce the day before his sudden illness when walking to a restaurant in a surprisingly warm evening that preluded the snowstorm on December 18th, 2019. With this article, we wish to celebrate Bruce's untouched love for Neuroscience.

Rapid non-genomic actions of 25(OH)D3: state of the art

Over recent years, the secosteroid hormone calcitriol (1α,25(OH)2D3) has been attracting growing attention due to its essential role in calcium absorption and bone mineralization. This hormone elicits these functions through genomic and non-genomic mechanisms. In the former case, the interaction of 1α,25(OH)2D3 with vitamin D receptor (VDR) results in the transcription of genes involved in the regulation of calcium homeostasis. Compared with their genomic counterparts, non-transcriptional effects, on the other hand, occur rapidly and are not subject to the effects of transcription and protein synthesis inhibitors; they have also been shown to be responsible for the multiple actions of vitamin D. The direct precursor metabolite of 1α,25(OH)2D3, calcifediol (25(OH)D3), which also exhibits anti-proliferative and gene regulatory properties, was recently described as an agonistic ligand of VDR, albeit with lower affinity than 1α,25(OH)2D3. This mini-review attempts to offer an overview of the non-genomic actions of calcifediol and the possible mechanisms underlying the generation of these rapid responses. Insights into the rapid non-genomic mechanisms of 25(OH)D3 could help to increase knowledge of the vitamin D endocrine system, and thus result in the identification of novel therapeutic strategies able to regulate non-genomic actions, which could prove crucial in 25(OH)D3 deficiency-related disorders.

The cortisol switch between vulnerability and resilience.

In concert with neuropeptides and transmitters, the end products of the hypothalamus-pituitary-adrenal (HPA) axis, the glucocorticoid hormones cortisol and corticosterone (CORT), promote resilience: i.e., the ability to cope with threats, adversity, and trauma. To exert this protective action, CORT activates mineralocorticoid receptors (MR) and glucocorticoid receptors (GR) that operate in a complementary manner -as an on/off switch- to coordinate circadian events, stress-coping, and adaptation. The evolutionary older limbic MR facilitates contextual memory retrieval and supports an on-switch in the selection of stress-coping styles at a low cost. The rise in circulating CORT concentration after stress subsequently activates a GR-mediated off-switch underlying recovery of homeostasis by providing the energy for restraining the primary stress reactions and promoting cognitive control over emotional reactivity. GR activation facilitates contextual memory storage of the experience to enable future stress-coping. Such complementary MR-GR-mediated actions involve rapid non-genomic and slower gene-mediated mechanisms; they are time-dependent, conditional, and sexually dimorphic, and depend on genetic background and prior experience. If coping fails, GR activation impairs cognitive control and promotes emotional arousal which eventually may compromise resilience. Such breakdown of resilience involves a transition to a chronic stress construct, where information processing is crashed; it leads to an imbalanced MR-GR switch and hence increased vulnerability. Novel MR-GR modulators are becoming available that may reset a dysregulated stress response system to reinstate the cognitive flexibility required for resilience.

Does GPER Really Function as a G Protein-Coupled Estrogen Receptor in vivo?

Estrogen can elicit pleiotropic cellular responses via a diversity of estrogen receptors (ERs)—mediated genomic and rapid non-genomic mechanisms. Unlike the genomic responses, where the classical nuclear ERα and ERβ act as transcriptional factors following estrogen binding to regulate gene transcription in estrogen target tissues, the non-genomic cellular responses to estrogen are believed to start at the plasma membrane, leading to rapid activation of second messengers-triggered cytoplasmic signal transduction cascades. The recently acknowledged ER, GPR30 or GPER, was discovered in human breast cancer cells two decades ago and subsequently in many other cells. Since its discovery, it has been claimed that estrogen, ER antagonist fulvestrant, as well as some estrogenic compounds can directly bind to GPER, and therefore initiate the non-genomic cellular responses. Various recently developed genetic tools as well as chemical ligands greatly facilitated research aimed at determining the physiological roles of GPER in different tissues. However, there is still lack of evidence that GPER plays a significant role in mediating endogenous estrogen action in vivo. This review summarizes current knowledge about GPER, including its tissue expression and cellular localization, with emphasis on the research findings elucidating its role in health and disease. Understanding the role of GPER in estrogen signaling will provide opportunities for the development of new therapeutic strategies to strengthen the benefits of estrogen while limiting the potential side effects.

Glucocorticoids in Graves’ orbitopathy: mechanisms of action and clinical application

Background:Graves’ orbitopathy (GO) is the most frequent extrathyroidal manifestation of the autoimmune Graves’ disease. GO significantly impacts quality of life and has a psycho-social morbidity. Inflammation and swelling of the orbital tissue often leads to proptosis, diplopia, and decrease of visual acuity. Due to the inflammatory background of the disease, glucocorticoids (GC) have been used as a first-line treatment for decades.Methods:PubMed and MeSH database were searched for original articles, clinical trials, reviews, and meta-analyses published between 1 January 2000 and 31 March 2020 and pertaining to both the mechanism of action and immunological effects of GC as well as to the treatment of GO by GC. The publications were evaluated according to their setting and study design.Results:GC act through genomic (trans-activation and trans-repression) and rapid non-genomic mechanisms. GC in general, and the intravenous (IV) administration of GC in particular, markedly decrease the activity and number of the most potent antigen-presenting dendritic cells. According to the internationally acknowledged European Thyroid Association Guidelines for the management of GO, weekly IVGC application over 12 weeks is recommended as first-line treatment for patients with active and severe GO. The daily and cumulative dose should be tailored according to clinical severity, for example, 4.5 g of IV methylprednisolone for the inflammatory component versus 7.5 g in the presence of diplopia and severe proptosis. Fast and significant improvements in orbital symptoms and signs are noted in 65–70% of patients. Long-term experience over decades, and worldwide availability at low cost, underline the clinical and therapeutic relevance of GC. Adverse events are rarely severe, dose-dependent, and usually reversible, hence easy to handle by medical investigators. Oral GC application on a daily basis is characterized by high bioavailability but reduced efficacy and increased toxicity.Conclusion:IVGC still represents the standard of care in active/severe GO. Innovative biologicals, like monoclonal antibodies targeting the thyrotropin/Insulin-like growth factor-1 receptors or pro-inflammatory cytokines (e.g., Interleukin-6) should be compared with standard GC treatment with respect to short- and long-term efficacy, safety, costs, and global availability.

Genomic sequence analyses of classical and non-classical lamprey progesterone receptor genes and the inference of homologous gene evolution in metazoans

BackgroundNuclear progesterone receptor (nPR) is an evolutionary innovation in vertebrates that mediates genomic responses to progesterone. Vertebrates also respond to progesterone via membrane progesterone receptors (mPRs) or membrane associated progesterone receptors (MAPRs) through rapid nongenomic mechanisms. Lampreys are extant agnathan vertebrates, residing at the evolutionary juncture where vertebrates diverged from invertebrates. A survey of the progesterone receptor (PR) gene sequences in lamprey genomes would inform PR gene evolutionary events during the transition from invertebrates to vertebrates.ResultsIn this study, we annotated sequences of one nPR, four mPR (β, γ, δ and ε) and four MAPR genes from genomes of two lamprey species (Petromyzon marinus and Lethenteron japonicum). To infer the origin and evolutionary history of PR genes, we constructed phylogenetic trees of PR homologous sequences across representative species of metazoans. Phylogenetic analyses revealed that the mPRγ gene first appeared in non-bilaterians, and the mPRβ gene likely arose from a duplication of mPRγ. On the other hand, the mPRγ gene gave rise to the mPRδ and ε genes much later in the vertebrate lineage. In addition, the mPRα gene first appeared in cartilaginous fishes, likely derived from duplication of mPRβ after the agnathan-gnathostome divergence. All known MAPR genes were present in the lamprey genomes. Progesterone receptor membrane component 1 (PGRMC1), neudesin and neuferricin genes probably evolved in parallel in non-bilaterians, whereas two copies of PGRMC genes probably derived from duplication of ancestral PGRMC1 sequence and appeared before the speciation of lampreys.ConclusionsNon-classical mPR and MAPR genes first evolved in non-bilaterians and classical nPR genes evolved later in basal vertebrates. Sequence repertoires for membrane progesterone receptor genes in vertebrates likely originated from an ancestral metazoan sequence and expanded via several duplication events.

Neurosteroids: current perspective in therapy of neuropsychiatric disorders

Neurosteroids are natural or synthetic steroid derivatives which act locally in brain by modulating neuronal excitability. The objective of this study is to analyze available literature on classification, biosynthesis and mechanism of action, and therapeutic potential of neurosteroids. A review of literature pertaining to neurosteroids published from inception to 2018 was carried on data bases like PUBMED, Google Scholar and Science Direct. The search terms used were neurosteroids, neuro-active steroids, ganaxolone and GABA-A receptor modulators. Review of literature suggests neurosteroids are powerful neuro-modulators, involving rapid non-genomic and non-hormone receptor mechanisms. They are classified based on structure as pregnane, androstane and sulphated neurosteroids, and based on function as excitatory or inhibitory neurosteroids. They act via GABAA receptor (primarily), rho- GABA (ρGABA), NMDA-glutamate and sigma receptor modulation. The inhibitory neurosteroids demonstrate sedative, anxiolytic and anticonvulsant actions, whereas the excitatory agents produce memory enhancing and anxiogenic effects. They show efficacy in various CNS and psychiatric conditions like epilepsy, anxiety, depression, learning and memory disorders and substance abuse. Endogenous neurosteroids have limited clinical use due to low bioavailability, lack of specificity and unwanted effects. Hence, synthetic agents like alphaxalone, ganaxolone, sepranolone and brexanolone which have better bioavailability and specificity, are being investigated in various phases of clinical trials. Neurosteroids are novel endogenous compounds with neuro-modulatory function and show promising effects in therapy of various neurological and psychiatric conditions. Further studies that prove their long term efficacy and safety may revolutionize the clinical approach to therapy of these conditions.

Comparative Study of the Effects of Acute In Vitro and Short‐term In Vivo Treatments with 3, 5, 3′ Triiodo‐L‐Thyronine on Contractile Responsiveness of Isolated Rat Thoracic Aorta

This work was aimed to study comparatively the influences of acute in vitro and short‐term in vivo treatments with 3, 5, 3′ triiodo‐L‐thyronine (T3) on the contractile responsiveness of isolated rat thoracic aortas. Previous studies have reported that T3 through nongenomic and genomic mechanisms can elicit endothelium‐dependent and ‐independent, nitric oxide (NO)‐mediated, depression of vascular tone. Short‐term in vivo treatment (hyperthyroidism) was established by subcutaneous injections of T3 (500 mg/kg/day) for 3 days (T33d); while control rats received vehicle (alkaline saline solution) for 3 days (V3d). T33d treatment was sufficient to cause both significant weight loss and elevation of T3 serum levels in the rat. In endothelium‐intact aortic rings contracted with phenylephrine, in vitro application of increasing cumulative concentrations of T3, each 30 minutes (0.01, 0.1, 1 and 10 mM), did not alter the contractile tone compared to vehicle treated tissues. Likewise, in vitro treatment with T3 (0.1, 1 and 10 mM for 30 min or 2 hs) did not modify the relaxant responses induced by either acetylcholine or sodium nitroprusside, in that order, in endothelium‐intact and ‐denuded aortic rings contracted with phenylephrine. (In aortic rings with and without endothelium, phenylephrine‐induced precontractions were not modified by preceding exposure to T3 compared to their corresponding vehicle‐treated tissues.) The concentration‐dependent contractions caused by phenylephrine and angiotensin II in aortic rings with endothelium, remained unchanged in the presence of T3 (0.1, 1 and 10 mM) applied 30 min or 2 h before. On the other hand, T33d treatment significantly decreased the contractile responses induced by phenylephrine and angiotensin II in aortic rings with and without endothelium, related to their respective controls. The absence of endothelium or the addition of the NO synthase inhibitor, L‐NAME, in the presence of endothelium (100 mM), independently, enhanced the contractile responses to phenylephrine in aortic rings of T33d and V3d rats. However, the contractile responses to phenylephrine remained similarly depressed in endothelium‐denuded and endothelium‐intact L‐NAME‐treated aortas of T33d compared to V3d rats. In conclusion, T3 applied in vitro does not alter the development of active tone in the endothelium‐intact and ‐denuded thoracic aortas, which rules out a direct action, by a rapid non‐genomic mechanism, of this hormone in smooth muscle and endothelial cells. On the other hand, short‐term in vivo administration of T3 depressed contractile responsiveness of the thoracic aorta, independently of endothelium and NO (whether of endothelial or muscle origin). It remains to elucidate if the T3‐induced depression of aortic contractility is due to direct hormonal effects or is secondary to a hyperdynamic cardiovascular state in hyperthyroid rats.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Brief Report: Low-Dose Hydrocortisone Has Acute Enhancing Effects on Verbal Learning in HIV-Infected Men.

Glucocorticoids are released in response to stress and alter cognition and brain function through both rapid nongenomic and slow genomic mechanisms. Administration of glucocorticoids in the form of hydrocortisone enhances aspects of learning and memory in individuals with PTSD but impairs these abilities in healthy individuals. We examine the time-dependent effects of glucocorticoids on cognition in HIV-infected men. In a double-blind placebo-controlled crossover study, we examined the time-dependent effects of a single low dose of hydrocortisone [10 mg; low-dose hydrocortisone (LDH)] on cognition in 45 HIV-infected men. Participants were randomized to receive either LDH or placebo and one month later, were given the opposite treatment. At each intervention session, cognition was assessed 30 minutes (assessing nongenomic effects) and 4 hours (assessing genomic effects) after pill administration. Self-reported stress/anxiety and cortisol/cytokines in saliva were measured throughout each session. Compared with placebo, LDH doubled salivary cortisol levels. Cortisol returned to baseline 4 hours postadministration. At the 30-minute assessment, LDH enhanced verbal learning compared with placebo. Greater increases in cortisol were associated with greater enhancements in verbal learning. LDH did not affect subjective stress/anxiety or any other cognitive outcomes at the 30-minute or 4-hour time point. The rapid effects of LDH on verbal learning suggests a nongenomic mechanism by which glucocorticoids can enhance cognition in HIV-infected men. The nonenduring nature of this enhancement may limit its clinical utility but provides insight into mechanisms underlying the effects of acute glucocorticoids on learning.

Rapid permissive action of dexamethasone on the regulation of blood pressure in a rat model of septic shock.

Glucocorticoids (GCs) play a vital role in the regulation of blood pressure by their permissive effects in potentiating vasoactive responses to catecholamines through glucocorticoid receptors. GCs achieve this function by controlling vascular smooth muscle tone. Clinically, low to moderate doses of GCs are generally used in the treatment of septic shock in recent years. GCs are now known to have both genomic and non-genomic effects. While genomic effects of GCs were well studied, few non-genomic effects were reported, much less the non-genomic mechanisms. One of the most important characters of their non-genomic effects is short latency. The aim of this study was to determine whether GCs can rapidly regulate blood pressure by their permissive action on norepinephrine (NE). Adrenalectomized rats were subjected to cecal ligation and puncture to induce septic shock. The septic rats displayed a significant decrease in the blood pressure response to NE. Dexamethasone (DEX) rapidly restores this hyporeactivity to NE in adrenalectomized septic rats. Further studies showed that DEX potentiates the NE-induced shrinkage and actin cytoskeleton rearrangement of single cell from mesenteric arteries in a short time. These findings suggest that GCs probably exert their permissive actions on the pressure response to NE through rapid non-genomic mechanisms. In this article, we found that as an adjunctive therapy for septic shock, the use of GCs may involve a rapid permissive action, and non-genomic effects of GCs may be involved in these processes.

Pioglitazone rapidly reduces neuropathic pain through astrocyte and nongenomic PPARγ mechanisms

Repeated administration of peroxisome proliferator-activated receptor gamma (PPARγ) agonists reduces neuropathic pain-like behavior and associated changes in glial activation in the spinal cord dorsal horn. As PPARγ is a nuclear receptor, sustained changes in gene expression are widely believed to be the mechanism of pain reduction. However, we recently reported that a single intrathecal (i.t.) injection of pioglitazone, a PPARγ agonist, reduced hyperalgesia within 30 minutes, a time frame that is typically less than that required for genomic mechanisms. To determine the very rapid antihyperalgesic actions of PPARγ activation, we administered pioglitazone to rats with spared nerve injury and evaluated hyperalgesia. Pioglitazone inhibited hyperalgesia within 5 minutes of injection, consistent with a nongenomic mechanism. Systemic or i.t. administration of GW9662, a PPARγ antagonist, inhibited the antihyperalgesic actions of intraperitoneal or i.t. pioglitazone, suggesting a spinal PPARγ-dependent mechanism. To further address the contribution of nongenomic mechanisms, we blocked new protein synthesis in the spinal cord with anisomycin. When coadministered intrathecally, anisomycin did not change pioglitazone antihyperalgesia at an early 7.5-minute time point, further supporting a rapid nongenomic mechanism. At later time points, anisomycin reduced pioglitazone antihyperalgesia, suggesting delayed recruitment of genomic mechanisms. Pioglitazone reduction of spared nerve injury-induced increases in GFAP expression occurred more rapidly than expected, within 60 minutes. We are the first to show that activation of spinal PPARγ rapidly reduces neuropathic pain independent of canonical genomic activity. We conclude that acute pioglitazone inhibits neuropathic pain in part by reducing astrocyte activation and through both genomic and nongenomic PPARγ mechanisms.

Molecular actions of 17β-estradiol and progesterone and their relationship with cellular signaling pathways

SEX STEROIDS: 17β-estradiol and progesterone play a major role in modulation of reproductive functions of the organism and participate in regulation of a broad spectrum of cellular processes in target cells via their specific receptors. Our understanding of molecular mechanisms of sex steroid action has significantly developed over the last years. Apart from the well-established effect of sex steroids on regulation of gene expression, some rapid nongenomic mechanisms have been identified, which are involved in modulation of the activity of several cellular, membrane-bound and cytoplasmic regulatory proteins. 17β-estradiol and progesterone regulate several signal transduction pathways, which involve activation of enzymes such as mitogen-activated protein kinases (MAPK), phosphatidylinositol 3-kinase and tyrosine kinases. Biological effects of sex steroids action constitute a complex interplay of genomic and nongenomic mechanisms, and depend on the physiological and genetic context of the target cell. Understanding the molecular mechanisms of sex steroids action is therefore important and may broaden our knowledge about their role in both physiological and pathological processes. This review provides a comprehensive insight into the molecular actions of 17β-estradiol and progesterone, aiming to present the role of these sex steroids in regulation of cellular signaling pathways.

Enhanced oxidative stress/DAPK3/Akt/ERK signaling accounts for estrogen exacerbation of cardiac dysfunction caused by ethanol in male rats (652.20)

We have previously shown that acute ethanol reduces blood pressure (BP) and cardiac output in female, but not in male, rats. Because these effects of ethanol were estrogen (E2)‐dependent, we investigated whether E2 treatment of male rats uncovers a hypotensive effect for ethanol, and whether left ventricular (LV) dysfunction, due to oxidative damage, contributes to the ethanol‐E2 hemodynamic interaction. The effect of ethanol (0.5, 1 or 1.5 g/kg; i.v.) on BP, LV function, and oxidative stress markers in male rats treated with E2 (1 μg/kg i.v.) or the vehicle were investigated. While ethanol had no effect on BP in vehicle‐treated rats, it caused dose‐related falls in BP in E2‐pretreated rats. This was associated with (i) compromised myocardial function as suggested by the reductions in LV developed pressure (LVDP), end diastolic pressure (LVEDP), and rate of rise in LV pressure (LV dP/dtmax), and (ii) oxidative damage as evidenced by the increases in LV generation of reactive oxygen species, protein expression of the malondialdehyde adducts, and phosphorylated death‐associated protein kinase‐3 (DAPK3), Akt, and ERK1/2. Together, E2 propagates LV dysfunction and hypotension in response to ethanol in male rats via facilitation of the myocardial oxidative stress/lipid peroxidation/DAPK3/Akt/ERK1/2 cascade. Because E2 was administered acutely, its effects are likely to involve rapid nongenomic mechanisms. Grant Funding Source: Supported by NIAAA [2R01 AA014441‐07].

Making memories of stressful events: a journey along epigenetic, gene transcription, and signaling pathways.

Strong psychologically stressful events are known to have a long-lasting impact on behavior. The consolidation of such, largely adaptive, behavioral responses to stressful events involves changes in gene expression in limbic brain regions such as the hippocampus and amygdala. However, the underlying molecular mechanisms were until recently unresolved. More than a decade ago, we started to investigate the role of glucocorticoid hormones in signaling and epigenetic mechanisms participating in the effects of stress on gene transcription in hippocampal neurons. We discovered a novel, rapid non-genomic mechanism in which glucocorticoids via glucocorticoid receptors facilitate signaling of the ERK-MAPK signaling pathway to the downstream nuclear kinases MSK1 and Elk-1 in dentate gyrus granule neurons. Activation of this signaling pathway results in serine10 (S10) phosphorylation and lysine14 (K14) acetylation at histone H3 (H3S10p-K14ac), leading to the induction of the immediate-early genes c-Fos and Egr-1. In addition, we found a role of the DNA methylation status of gene promoters. A series of studies showed that these molecular mechanisms play a critical role in the long-lasting consolidation of behavioral responses in the forced swim test and Morris water maze. Furthermore, an important role of GABA was found in controlling the epigenetic and gene transcriptional responses to psychological stress. Thus, psychologically stressful events evoke a long-term impact on behavior through changes in hippocampal function brought about by distinct glutamatergic and glucocorticoid-driven changes in epigenetic regulation of gene transcription, which are modulated by (local) GABAergic interneurons and limbic afferent inputs. These epigenetic processes may play an important role in the etiology of stress-related mental disorders such as major depressive and anxiety disorders like post-traumatic stress disorder.

Stress and decision making: A few minutes make all the difference

Stress has been shown to impair decision making. However the temporal development of this phenomenon remains poorly understood. We speculated that the rapid stress induced increase in norepinephrine and the delayed increase in cortisol might exert opposing effects on decision making under risk. Therefore, three different experimental groups underwent the Trier Social Stress Test (TSST) and performed the Game of Dice Task (GDT) at different time points in relation to the stressor, which lasted approximately 18min. The first group performed the GDT 5min after stress onset, the second and third group performed the GDT either 18 or 28min after TSST onset. Decision-making performance of the control group was measured after a respective resting time. Results confirmed a rapid activation of the sympathetic nervous system and a somewhat slower response of the hypothalamic pituitary adrenal axis. In the GDT an improvement of decision-making performance in the 5 and 18min stress groups compared to controls and the 28min stress group occurred. Descriptively, decision making of the 28min after stress group was more risky than decision making of the control group. Our findings are in line with the idea that a moderate increase in catecholamines enhances decision-making performance, while elevated cortisol concentrations may negatively affect decision making presumably via rapid nongenomic mechanisms.

Non-genomic action of beclomethasone dipropionate on bronchoconstriction caused by leukotriene C4 in precision cut lung slices in the horse

BackgroundGlucocorticoids have been proven to be effective in the therapy of recurrent airway obstruction (RAO) in horses via systemic as well as local (inhalative) administration. Elective analysis of the effects of this drug on bronchoconstriction in viable lung tissue offers an insight into the mechanism of action of the inflammatory cascade occurring during RAO which is still unclear. The mechanism of action of steroids in treatment of RAO is thought to be induced through classical genomic pathways. We aimed at electively studying the effects of the glucocorticoid beclomethasone dipropionate on equine precision-cut lung slices (PCLS).PCLS were used to analyze ex-vivo effects of beclomethasone on inhibiting bronchoconstriction in the horse. The inhibiting effect was measured through instillation of a known mediator of inflammation and bronchoconstriction, leukotriene C4. For this, the accessory lobes of 13 horses subjected to euthanasia for reasons unrelated to the respiratory apparatus were used to obtain viable lung slices.ResultsAfter 30 minutes of PCLS incubation, beclomethasone showed to significantly inhibit the contraction of the bronchioles after instillation with leukotriene C4. The EC50 values of the two contraction curves (LTC4 with and without BDP) differed significantly from each other (p = 0.002). The possibility of a non-genomic rapid mechanism of action seems likely since transcriptional activities require a longer lag period.ConclusionsIn human neuroendocrinology, high levels of glucocorticoids have been proven to function via a non-genomic mechanism of membrane receptors. The concentration of beclomethasone used on the lung slices in our study can be considered as high. This allows speculation about similar rapid non-genomic mechanisms of high-dosage inhaled glucocorticoids in the lower airways of horses. However, further assessment on a molecular basis is needed to confirm this.

Peroxisome-proliferator-activated receptor gamma (PPARγ) is required for modulating endothelial inflammatory response through a nongenomic mechanism

Besides their well-known anti-diabetic effects, the peroxisome-proliferator-activated receptor γ (PPARγ) thiazolidinedione ligands (TZD) have been suggested to also display anti-inflammatory properties. The receptor role in mediating such effects is far from being elucidated. Here, we demonstrated that PPARγ is necessary for TZD to interfere with TNFα and IFNγ inflammatory activity in human endothelial cells. Different PPARγ ligands similarly inhibit cytokinic stimulation of IFNγ-inducible-protein-of-10-kDa (IP10) secretion in a dose-dependent manner and prevent the induced phosphorylation/activation of extracellular-signaling-regulated-kinases (ERK1/2). To further confirm the PPARγ role in mediating both rapid and long term anti-inflammatory effects of its ligands, we evaluated RGZ inhibitory action in PPARγ-silenced and -overexpressing cells. PPARγ-silencing results in a reversion of RGZ inhibitory activity on cyto/chemokine secretions and rapid ERK phosphorylation. Conversely, receptor overexpression significantly increases RGZ inhibitory activity. Finally, PPARγ-overexpression results in a reduction of ERK1/2 phosphorylation and inflammatory secretions in response to TNFα and IFNγ even in the absence of RGZ, suggesting a restraining effect controlled by endogenous ligands.In conclusion, our data provide the first evidence that PPARγ is involved in the anti-inflammatory action of TZD in endothelial cells, not only by modulating cyto/chemokine secretions but also by restraining ERK activation through a novel rapid nongenomic mechanism.

The platelet as a model system for the acute actions of nuclear receptors

Platelets are circulating cell fragments which play a critical role in thrombosis, and whose activity is associated with the progress of cardiovascular diseases, diabetes, inflammation, and cancer cell metastasis. Recently, a number of nuclear receptors have been found present in human platelets, including the receptors for sex steroids, and glucocorticoids, along with peroxisome proliferator-activated receptors (PPAR)s and retinoid X receptors (RXR)s. Although the platelet contains no nucleus, selective ligands for these receptors activate their respective platelet nuclear receptors and regulate platelet aggregation and activation. The human platelet, because of its abundance and accessibility therefore represents an excellent model system to study the rapid non-genomic mechanism of nuclear receptors. Moreover, since targeting platelets is a major clinical therapeutic area, analysis of platelet nuclear receptors may provide clues for new drug targets as well as provide important information regarding the physiological roles of nuclear receptors in the circulation.

Estrogen exerts concentration-dependent pro-and anti-hypertrophic effects on adult cultured ventricular myocytes. Role of NHE-1 in estrogen-induced hypertrophy

Estrogen has been shown to protect the heart and attenuate myocardial hypertrophy and left ventricular remodelling through as yet to be defined mechanisms. In the present study we examined concentration-dependent effects of estrogen on hypertrophy of adult rat cardiomyocytes, potential underlying mechanisms related to intracellular pH (pH i) and possible sex-dependent responses. Cardiomyocytes were isolated from adult male and female Sprague–Dawley rats and used immediately for pH i determinations or cultured and subsequently treated for 24 h with 17β-estradiol to assess hypertrophic responses. Fluorometric measurements with the pH i-sensitive dye BCECF demonstrated that at 1 pM 17β-estradiol increased pH i (+ 0.05 pH units in females and + 0.12 pH units in males, P < 0.05) by a rapid non-genomic mechanism that was blocked by the sodium-hydrogen exchange isoform 1 (NHE-1) specific inhibitor AVE-4890 (AVE, 5 μM). Treatment with 1 pM 17β-estradiol for 24 h increased cell size (females: 20%, P < 0.05; males: 29%, P < 0.05) and ANP expression (females: 414%, P < 0.05; males: 497%, P < 0.05) in a NHE-1-, and ERK1/2 MAPK-dependent manner. At 1 nM, 17β-estradiol decreased pH i (females: − 0.24 pH units, P < 0.05; males: − 0.07 pH units, P < 0.05) which was also prevented by AVE, although at this concentration the hormone had no direct hypertrophic effect but instead prevented hypertrophy induced by phenylephrine. Our results show that low levels of estrogen produce cardiomyocyte hypertrophy through ERK/NHE-1 activation and intracellular alkalinization whereas an antihypertrophic effect is seen at high concentrations. These effects may further our understanding of the role of estrogen in heart disease particularly associated with hypertrophy.