Memory deficits in a juvenile rat model of type 1 diabetes are due to excess 11ß-HSD1 activity, which is upregulated by high glucose concentrations rather than insulin deficiency.

AIMS/HYPOTHESIS: Children with diabetes may display cognitive alterations although vascular disorders have not yet appeared. Variations in glucose levels together with relative insulin deficiency in treated type 1 diabetes have been reported to impact brain function indirectly through dysregulation of the hypothalamus-pituitary-adrenal axis. We have recently shown that enhancement of glucocorticoid levels in children with type 1 diabetes is dependent not only on glucocorticoid secretion but also on glucocorticoid tissue concentrations, which is linked to 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) activity. Hypothalamus-pituitary-adrenal axis dysfunction and memory alteration were further dissected in a juvenile rat model of diabetes showing that excess 11ß-HSD1 activity within the hippocampus is associated with hippocampal-dependent memory deficits. Here, to investigate the causal relationships between diabetes, 11ß-HSD1 activity and hippocampus-dependent memory deficits, we evaluated the beneficial effect of 11ß-HSD1 inhibition on hippocampal-related memory in juvenile diabetic rats. We also examined whether diabetes-associated enhancement of hippocampal 11ß-HSD1 activity is due to an increase in brain glucose concentrations and/or a decrease in insulin signalling. METHODS: Diabetes was induced in juvenile rats by daily i.p. injection of streptozotocin for 2 consecutive days. Inhibition of 11ß-HSD1 was obtained by administrating the compound UE2316 twice daily by gavage for 3 weeks, after which hippocampal-dependent object location memory was assessed. Hippocampal 11ß-HSD1 activity was estimated by the ratio of corticosterone/dehydrocorticosterone measured by LC/MS. Regulation of 11ß-HSD1 activity in response to changes in glucose or insulin levels was determined ex vivo on acute brain hippocampal slices. The insulin regulation of 11ß-HSD1 was further examined in vivo using virally mediated knockdown of insulin receptor expression specifically in the hippocampus. RESULTS: Our data show that inhibiting 11ß-HSD1 activity prevents hippocampal-related memory deficits in diabetic juvenile rats. A significant increase (53.0±9.9%) in hippocampal 11ß-HSD1 activity was found in hippocampal slices incubated in high glucose conditions (13.9 mmol/l) vs normal glucose conditions (2.8 mmol/l) without insulin. However, 11ß-HSD1 activity was not affected by variations in insulin concentration either in the hippocampal slices or after a decrease in hippocampal insulin receptor expression. CONCLUSIONS/INTERPRETATION: Together, these data demonstrate that an increase in 11ß-HSD1 activity contributes to memory deficits observed in juvenile diabetic rats and that an excess of hippocampal 11ß-HSD1 activity stems from high glucose levels rather than insulin deficiency. 11ß-HSD1 might be a therapeutic target for treating cognitive impairments associated with diabetes.

Reshaping circadian metabolism in the suprachiasmatic nucleus and prefrontal cortex by nutritional challenge.

Food is a powerful entrainment cue for circadian clocks in peripheral tissues, and changes in the composition of nutrients have been demonstrated to metabolically reprogram peripheral clocks. However, how food challenges may influence circadian metabolism of the master clock in the suprachiasmatic nucleus (SCN) or in other brain areas is poorly understood. Using high-throughput metabolomics, we studied the circadian metabolome profiles of the SCN and medial prefrontal cortex (mPFC) in lean mice compared with mice challenged with a high-fat diet (HFD). Both the mPFC and the SCN displayed a robust cyclic metabolism, with a strikingly high sensitivity to HFD perturbation in an area-specific manner. The phase and amplitude of oscillations were drastically different between the SCN and mPFC, and the metabolic pathways impacted by HFD were remarkably region-dependent. Furthermore, HFD induced a significant increase in the number of cycling metabolites exclusively in the SCN, revealing an unsuspected susceptibility of the master clock to food stress.

Dietary vitamin A supplementation prevents early obesogenic diet-induced microbiota, neuronal and cognitive alterations.

BACKGROUND: Early consumption of obesogenic diets, rich in saturated fat and added sugar, is associated with a plethora of biological dysfunctions, at both peripheral and brain levels. Obesity is also linked to decreased vitamin A bioavailability, an essential molecule for brain plasticity and memory function. METHODS: Here we investigated in mice whether dietary vitamin A supplementation (VAS) could prevent some of the metabolic, microbiota, neuronal and cognitive alterations induced by obesogenic, high-fat and high-sugar diet (HFSD) exposure from weaning to adulthood, i.e. covering periadolescent period. RESULTS: As expected, VAS was effective in enhancing peripheral vitamin A levels as well as hippocampal retinoic acid levels, the active metabolite of vitamin A, regardless of the diet. VAS attenuated HFSD-induced excessive weight gain, without affecting metabolic changes, and prevented alterations of gut microbiota α-diversity. In HFSD-fed mice, VAS prevented recognition memory deficits but had no effect on aversive memory enhancement. Interestingly, VAS alleviated both HFSD-induced higher neuronal activation and lower glucocorticoid receptor phosphorylation in the hippocampus after training. CONCLUSION: Dietary VAS was protective against the deleterious effects of early obesogenic diet consumption on hippocampal function, possibly through modulation of the gut-brain axis.

Sexual Dimorphism in Glucocorticoid Stress Response.

Chronic stress is encountered in our everyday life and is thought to contribute to a number of diseases. Many of these stress-related disorders display a sex bias. Because glucocorticoid hormones are the main biological mediator of chronic stress, researchers have been interested in understanding the sexual dimorphism in glucocorticoid stress response to better explain the sex bias in stress-related diseases. Although not yet demonstrated for glucocorticoid regulation, sex chromosomes do influence sex-specific biology as soon as conception. Then a transient rise in testosterone start to shape the male brain during the prenatal period differently to the female brain. These organizational effects are completed just before puberty. The cerebral regions implicated in glucocorticoid regulation at rest and after stress are thereby impacted in a sex-specific manner. After puberty, the high levels of all gonadal hormones will interact with glucocorticoid hormones in specific crosstalk through their respective nuclear receptors. In addition, stress occurring early in life, in particular during the prenatal period and in adolescence will prime in the long-term glucocorticoid stress response through epigenetic mechanisms, again in a sex-specific manner. Altogether, various molecular mechanisms explain sex-specific glucocorticoid stress responses that do not exclude important gender effects in humans.

The Stress-Induced Transcription Factor NR4A1 Adjusts Mitochondrial Function and Synapse Number in Prefrontal Cortex.

The energetic costs of behavioral chronic stress are unlikely to be sustainable without neuronal plasticity. Mitochondria have the capacity to handle synaptic activity up to a limit before energetic depletion occurs. Protective mechanisms driven by the induction of neuronal genes likely evolved to buffer the consequences of chronic stress on excitatory neurons in prefrontal cortex (PFC), as this circuitry is vulnerable to excitotoxic insults. Little is known about the genes involved in mitochondrial adaptation to the buildup of chronic stress. Using combinations of genetic manipulations and stress for analyzing structural, transcriptional, mitochondrial, and behavioral outcomes, we characterized NR4A1 as a stress-inducible modifier of mitochondrial energetic competence and dendritic spine number in PFC. NR4A1 acted as a transcription factor for changing the expression of target genes previously involved in mitochondrial uncoupling, AMP-activated protein kinase activation, and synaptic growth. Maintenance of NR4A1 activity by chronic stress played a critical role in the regressive synaptic organization in PFC of mouse models of stress (male only). Knockdown, dominant-negative approach, and knockout of Nr4a1 in mice and rats (male only) protected pyramidal neurons against the adverse effects of chronic stress. In human PFC tissues of men and women, high levels of the transcriptionally active NR4A1 correlated with measures of synaptic loss and cognitive impairment. In the context of chronic stress, prolonged expression and activity of NR4A1 may lead to responses of mitochondria and synaptic connectivity that do not match environmental demand, resulting in circuit malfunction between PFC and other brain regions, constituting a pathological feature across disorders.SIGNIFICANCE STATEMENT The bioenergetic cost of chronic stress is too high to be sustainable by pyramidal prefrontal neurons. Cellular checkpoints have evolved to adjust the responses of mitochondria and synapses to the buildup of chronic stress. NR4A1 plays such a role by controlling the energetic competence of mitochondria with respect to synapse number. As an immediate-early gene, Nr4a1 promotes neuronal plasticity, but sustained expression or activity can be detrimental. NR4A1 expression and activity is sustained by chronic stress in animal models and in human studies of neuropathologies sensitive to the buildup of chronic stress. Therefore, antagonism of NR4A1 is a promising avenue for preventing the regressive synaptic reorganization in cortical systems in the context of chronic stress.

Corticosteroid-Binding Globulin Deficiency Specifically Impairs Contextual and Recognition Memory Consolidation in Male Mice.

BACKGROUND/AIMS: Glucocorticoids are essential in modulating memory processes of emotionally arousing experiences and we have shown that corticosteroid-binding globulin (CBG) influences glucocorticoid delivery to the brain. Here, we investigated the role of CBG in contextual and recognition long-term memory according to stress intensity. METHOD: We used adult male mice totally deficient in CBG (Cbg KO) or brain-specific Cbg KO (CbgCamk KO) to examine their performance in contextual fear conditioning (CFC) and au-ditory fear conditioning, both at short (1 h) and long-term (24 h). Long-term memory in Cbg KO was further analyzed in conditioned odor aversion and in novel object recognition task (NORT) with different paradigms, that is, with and without prior habituation to the context, with a mild or strong stressor applied during consolidation. In the NORT experiments, total and free glucocorticoid levels were measured during consolidation. RESULTS: Impaired memory was observed in the Cbg KO but not in the CbgCamk KO in the CFC and the NORT without habituation when tested 24 h later. However, Cbg KO displayed normal behavior in the NORT with previous habituation and in the NORT with a mild stressor. In condition of the NORT with a strong stressor, Cbg KO retained good 24 h memory performance while controls were impaired. Total and free glucocorticoids levels were always higher in controls than in Cbg KO except in NORT with mild stressor where free glucocorticoids were equivalent to controls. CONCLUSIONS: These data indicate that circulating but not brain CBG influences contextual and recognition long-term memory in relation with glucocorticoid levels.

Deletion of the miR-379/miR-410 gene cluster at the imprinted Dlk1-Dio3 locus enhances anxiety-related behaviour.

The brain-specific miR-379/miR-410 gene cluster at the imprinted Dlk1-Dio3 domain is implicated in several aspects of brain development and function, particularly in fine-tuning the dendritic outgrowth and spine remodelling of hippocampal neurons. Whether it might influence behaviour and memory-related processes has not yet been explored at the whole organism level. We previously reported that constitutive deletion of the miR-379/miR-410 gene cluster affects metabolic adaptation in neonatal mice. Here, we examined the role of this cluster in adult brain functions by subjecting mice with the constitutive deletion to a battery of behavioural and cognitive tests. We found that the lack of miR-379/miR-410 expression is associated with abnormal emotional responses, as demonstrated by increased anxiety-related behaviour in unfamiliar environments. In contrast, spontaneous exploration, general locomotion, mood levels and sociability remained unaltered. Surprisingly, miR-379/miR-410-deficient mice also showed normal learning and spatial (or contextual) memory abilities in hippocampus-dependent tasks involving neuronal plasticity. Taken together, the imprinted miR-379/miR-410 gene cluster thus emerges as a novel regulator of the two main post-natal physiological processes previously associated with imprinted, protein-coding genes: behaviour and energy homeostasis.

Retinoic acid increases glucocorticoid receptor phosphorylation via cyclin-dependent kinase 5.

Glucocorticoid receptor (GR) function is modulated by phosphorylation. As retinoic acid (RA) can activate some cytoplasmic kinases able to phosphorylate GR, we investigated whether RA could modulate GR phosphorylation in neuronal cells in a context of long-term glucocorticoid exposure. A 4-day treatment of dexamethasone (Dex) plus RA, showed that RA potentiated the (Dex)-induced phosphorylation on GR Serine 220 (pSer220GR) in the nucleus of a hippocampal HT22 cell line. This treatment increased the cytoplasmic ratio of p35/p25 proteins, which are major CDK5 cofactors. Roscovitine, a pharmacological CDK5 inhibitor, or a siRNA against CDK5 prevented RA potentiation of GR phosphorylation. Furthermore, roscovitine counter-acted the effect of RA on GR sensitive target proteins such as BDNF or tissue-transglutaminase. These data help understanding the interaction between RA- and glucocorticoid-signalling pathways, both of which have strong influences on the adult brain.

Stress and glucocorticoid regulation of NR4A genes in mice.

The NR4A nuclear receptors subgroup, comprising Nur77 (NR4A1), Nurr1 (NR4A2), and Nor1 (NR4A3), are orphan receptors induced by a variety of signals, including stress. These receptors are described as early response genes and in vitro studies have shown that they take part in regulation of the hypothalamic-pituitary-adrenal (HPA) axis, the major stress-responsive neuroendocrine system. This study analyzes further the interweaving of NR4A receptors with the HPA axis at rest and after a restraint stress in vivo in mice. We show that each NR4A member has a similar mRNA expression pattern and low levels of expression at rest except, in particular in hippocampus for Nurr1 and in adrenals for Nur77. After restraint stress, mRNA expression of each NR4A is markedly induced in adrenals and pituitary and significantly in hypothalamus. In higher cerebral regions, such as cortex, hippocampus, and amygdala, induction of NR4A mRNA elicited by stress was very moderate or undetected. The influence of glucocorticoids on NR4A mRNA expression was analyzed by comparing wild-type and Cbg k.o. mice used as a model of glucocorticoid hyposignaling. Nur77 mRNA and protein expression and a downstream Nur77 target gene were found to be affected in the hypothalamus and pituitary of the Cbg k.o. mice but not in hippocampus and cortex. These results further support a physiological role of NR4A orphan receptors in the glucocorticoid response to stress.

Effect of a high-fat--high-fructose diet, stress and cinnamon on central expression of genes related to immune system, hypothalamic-pituitary-adrenocortical axis function and cerebral plasticity in rats.

The intake of a high-fat/high-fructose (HF/HFr) diet is described to be deleterious to cognitive performances, possibly via the induction of inflammatory factors. An excess of glucocorticoids is also known to exert negative effects on cerebral plasticity. In the present study, we assessed the effects of an unbalanced diet on circulating and central markers of inflammation and glucocorticoid activity, as well as their reversal by dietary cinnamon (CN) supplementation. A group of male Wistar rats were subjected to an immune challenge with acute lipopolysaccharide under a HF/HFr or a standard diet. Another group of Wistar rats were fed either a HF/HFr or a control diet for 12 weeks, with or without CN supplementation, and with or without restraint stress (Str) application before being killed. We evaluated the effects of such regimens on inflammation parameters in the periphery and brain and on the expression of actors of brain plasticity. To assess hypothalamic-pituitary-adrenocortical axis activity, we measured the plasma concentrations of corticosterone and the expression of central corticotrophin-releasing hormone, mineralocorticoid receptor, glucocorticoid receptor and 11ß-hydroxysteroid dehydrogenase. We found that the HF/HFr diet induced the expression of cytokines in the brain, but only after an immune challenge. Furthermore, we observed the negative effects of Str on the plasma concentrations of corticosterone and neuroplasticity markers in rats fed the control diet but not in those fed the HF/HFr diet. Additionally, we found that CN supplementation exerted beneficial effects under the control diet, but that its effects were blunted or even reversed under the HF/HFr diet. CN supplementation could be beneficial under a standard diet. [corrected].

Retinoids and glucocorticoids target common genes in hippocampal HT22 cells.

Vitamin A metabolite retinoic acid (RA) plays a major role in the aging adult brain plasticity. Conversely, chronic excess of glucocorticoids (GC) elicits some deleterious effects in the hippocampus. We questioned here the involvement of RA and GC in the expression of target proteins in hippocampal neurons. We investigated proteins involved either in the signaling pathways [RA receptor ß (RARß) and glucocorticoid receptor (GR)] or in neuron differentiation and plasticity [tissue transglutaminase 2 (tTG) and brain-derived neurotrophic factor (BDNF)] in a hippocampal cell line, HT22. We applied RA and/or dexamethasone (Dex) as activators of the pathways and investigated mRNA and protein expression of their receptors and of tTG and BDNF as well as tTG activity and BDNF secretion. Our results confirm the involvement of RA- and GC-dependent pathways and their interaction in our neuronal cell model. First, both pathways regulate the transcription and expression of own and reciprocal receptors: RA and Dex increased RARß and decreased GR expressions. Second, Dex reduces the expression of tTG when associated with RA despite stimulating its expression when used alone. Importantly, when they are combined, RA counteracts the deleterious effect of glucocorticoids on BDNF regulation and thus may improve neuronal plasticity under stress conditions. In conclusion, GC and RA both interact through regulations of the two receptors, RARß and GR. Furthermore, they both act, synergistically or oppositely, on other target proteins critical for neuronal plasticity, tTG and BDNF.

Intrinsic expression of transcortin in neural cells of the mouse brain: a histochemical and molecular study.

Corticosteroid binding globulin (CBG, transcortin) has been shown to be expressed in the brain of rat and human species. In this study, we examined the CBG brain expression and cDNA structure in mice, comparing wild-type (Cbg(+/+)) and Cbg knockout mice (Cbg(-/-), obtained by genetic disruption of the SerpinA6 alias Cbg gene). We used double immunofluorescence labeling with specific neuronal and glial markers to analyze the cellular localization of CBG in various regions of the mouse brain. In wild-type (Cbg(+/+)) mice, we found CBG immunoreactivity in neuronal perikarya of the magnocellular hypothalamic nuclei, amygdala, hippocampus, cerebral cortex, cerebellum and pituitary. A portion of glial cells (astrocytes, oligodendrocytes) contained CBG immunoreactivity, including some of the ependymal cells and choroid plexus cells. No CBG immunoreactivity was detected in Cbg(-/-) brain tissues. Using RT-PCR, we showed that the full-length Cbg mRNA is present in those regions, indicating an intrinsic expression of the steroid-binding globulin. Furthermore, sequencing analysis showed that Cbg cDNA obtained from the mouse hypothalamus was homologous to Cbg cDNA obtained from the liver. Finally, we have evaluated the relative levels of CBG expression in various brain regions and in the liver by quantitative PCR. We found that brain levels of Cbg mRNA are low compared with the liver but significantly higher than in CBG-deficient mice. Although derived from the same gene as liver CBG, brain CBG protein may play a specific or complementary role that requires the production and analysis of brain-specific Cbg knockout models.

Structural basis of glucocorticoid receptor signaling bias.

Dissociation between the healthy and toxic effects of cortisol, a major stress-responding hormone has been a widely used strategy to develop anti-inflammatory glucocorticoids with fewer side effects. Such strategy falls short when treating brain disorders as timing and activity state within large-scale neuronal networks determine the physiological and behavioral specificity of cortisol response. Advances in structural molecular dynamics posit the bases for engineering glucocorticoids with precision bias for select downstream signaling pathways. Design of allosteric and/or cooperative control for the glucocorticoid receptor could help promote the beneficial and reduce the deleterious effects of cortisol on brain and behavior in disease conditions.

Strain-specific changes in nucleus accumbens transcriptome and motivation for palatable food reward in mice exposed to maternal separation.

Introduction: In humans, adversity in childhood exerts enduring effects on brain and increases the vulnerability to psychiatric diseases. It also leads to a higher risk of eating disorders and obesity. Maternal separation (MS) in mice has been used as a proxy of stress during infancy. We hypothesized that MS in mice affects motivation to obtain palatable food in adulthood and changes gene expression in reward system. Methods: Male and female pups from C57Bl/6J and C3H/HeN mice strains were subjected to a daily MS protocol from postnatal day (PND) 2 to PND14. At adulthood, their motivation for palatable food reward was assessed in operant cages. Results: Compared to control mice, male and female C3H/HeN mice exposed to MS increased their instrumental response for palatable food, especially when the effort required to obtain the reward was high. Importantly, this effect is shown in animals fed ad libitum. Transcriptional analysis revealed 375 genes differentially expressed in the nucleus accumbens of male MS C3H/HeN mice compared to the control group, some of these being associated with the regulation of the reward system (e.g., Gnas, Pnoc). Interestingly, C57Bl/6J mice exposed to MS did not show alterations in their motivation to obtain a palatable reward, nor significant changes in gene expression in the nucleus accumbens. Conclusion: MS produces long-lasting changes in motivation for palatable food in C3H/HeN mice, but has no impact in C57Bl/6J mice. These behavioral alterations are accompanied by drastic changes in gene expression in the nucleus accumbens, a key structure in the regulation of motivational processes.

[Overview of acute and chronic stress responses]. / Le stress dans tous ses états.

The psychobiological concept of stress built up over the years since the 1930s. The understanding of the neurobiological mechanisms involved has progressed remarkably during the past years. This article provides an overview of the recent data opposing acute and chronic stress. The former is an adaptative response of the organism to cope with the fluctuations of the environment and thereby is essential for survival. By contrast, chronic stress is deleterious and leads to various disease states in vulnerable individuals. Its adverse effects on the brain and the body result from a dysregulation of the stress system with various origins and mechanisms which we will discuss in this review.

Diabetes and associated cognitive disorders: Role of the Hypothalamic-Pituitary Adrenal axis.

Both diabetes types, types 1 and 2, are associated with cognitive impairments. Each period of life is concerned, and this is an increasing public health problem. Animal models have been developed to investigate the biological actors involved in such impairments. Many levels of the brain function (structure, volume, neurogenesis, neurotransmission, behavior) are involved. In this review, we detailed the part potentially played by the Hypothalamic-Pituitary Adrenal axis in these dysfunctions. Notably, regulating glucocorticoid levels, their receptors and their bioavailability appear to be relevant for future research studies, and treatment development.

Microbiota and stress: a loop that impacts memory.

Chronic stress and the gut microbiota appear to comprise a feed-forward loop, which contributes to the development of depressive disorders. Evidence suggests that memory can also be impaired by either chronic stress or microbiota imbalance. However, it remains to be established whether these could be a part of an integrated loop model and be responsible for memory impairments. To shed light on this, we used a two-pronged approach in Japanese quail: first stress-induced alterations in gut microbiota were characterized, then we tested whether this altered microbiota could affect brain and memory function when transferred to a germ-free host. The cecal microbiota of chronically stressed quails was found to be significantly different from that of unstressed individuals with lower α and ß diversities and increased Bacteroidetes abundance largely represented by the Alistipes genus, a well-known stress target in rodents and humans. The transfer of this altered microbiota into germ-free quails decreased their spatial and cue-based memory abilities as previously demonstrated in the stressed donors. The recipients also displayed increased anxiety-like behavior, reduced basal plasma corticosterone levels and differential gene expression in the brain. Furthermore, cecal microbiota transfer from a chronically stressed individual was sufficient to mimic the adverse impact of chronic stress on memory in recipient hosts and this action may be related to the Alistipes genus. Our results provide evidence of a feed-forward loop system linking the microbiota-gut-brain axis to stress and memory function and suggest that maintaining a healthy microbiota could help alleviate memory impairments linked to chronic stress.

Combined Gene Expression and Chromatin Immunoprecipitation From a Single Mouse Hippocampus.

All neuronal cells hold the same genetic information but vary by their structural and functional plasticity depending on the brain area and environmental influences. Such variability involves specific gene regulation, which is driven by transcription factors (TFs). In the field of neuroscience, epigenetics is the main mechanism that has been investigated to understand the dynamic modulation of gene expression by behavioral responses, stress responses, memory processes, etc. Nowadays, gene expression analyzed by real-time quantitative PCR and TF binding estimated by chromatin immunoprecipitation (ChIP) enables one to dissect this regulation. Because of the wide range of transgenic models, as well as cost-effective aspects, mouse models are widely used neuroscience. Thus, we have set up a protocol that allows extraction of both RNA for gene expression analysis and chromatin for ChIP experiment from a single mouse hippocampus. Using such protocols, information regarding gene expression and regulatory molecular mechanisms from the same animal can be integrated and correlated with neurobiological and behavioral outcomes. © 2021 Wiley Periodicals LLC. Basic Protocol 1: Hippocampus isolation from mouse brain Basic Protocol 2: RNA extraction and gene expression analysis from a mouse half hippocampus Basic Protocol 3: ChIP from one hemisphere side mouse hippocampus.

Altered Cortisol Metabolism Increases Nocturnal Cortisol Bioavailability in Prepubertal Children With Type 1 Diabetes Mellitus.

Objective: Disturbances in the activity of the hypothalamus-pituitary-adrenal axis could lead to functional alterations in the brain of diabetes patients. In a later perspective of investigating the link between the activity of the hypothalamus-pituitary-adrenal axis and the developing brain in children with diabetes, we assessed here nocturnal cortisol metabolism in prepubertal children with type 1 diabetes mellitus (T1DM). Methods: Prepubertal patients (aged 6-12 years) diagnosed with T1DM at least 1 year previously were recruited, along with matched controls. Nocturnal urine samples were collected, with saliva samples taken at awakening and 30 minutes after awakening. All samples were collected at home over 5 consecutive days with no detectable nocturnal hypoglycaemia. The State-Trait Anxiety Inventory (trait scale only) and Child Depression Inventory were also completed. Glucocorticoid metabolites in the urine, salivary cortisol (sF) and cortisone (sE) were measured by liquid chromatography-tandem mass spectrometry. Metabolic data were analysed by logistic regression, adjusting for sex, age, BMI and trait anxiety score. Results: Urine glucocorticoid metabolites were significantly lower in T1DM patients compared to controls. 11ß-hydroxysteroid dehydrogenase type 1 activity was significantly higher, while 11ß-hydroxysteroid dehydrogenase type 2, 5(α+ß)-reductase and 5α-reductase levels were all lower, in T1DM patients compared to controls. There was a significant group difference in delta sE level but not in delta sF level between the time of awakening and 30 minutes thereafter. Conclusions: Our findings suggest that altered nocturnal cortisol metabolism and morning HPA axis hyperactivity in children with T1DM leads to greater cortisol bioavailability and lower cortisol production as a compensatory effect. This altered nocturnal glucocorticoid metabolism when cortisol production is physiologically reduced and this HPA axis hyperactivity question their impact on brain functioning.

Transcriptomic signaling pathways involved in a naturalistic model of inflammation-related depression and its remission.

This study aimed at identifying molecular biomarkers of inflammation-related depression in order to improve diagnosis and treatment. For this, we performed whole-genome expression profiling from peripheral blood in a naturalistic model of inflammation-associated major depressive disorder (MDD) represented by comorbid depression in obese patients. We took advantage of the marked reduction of depressive symptoms and inflammation following bariatric surgery to test the robustness of the identified biomarkers. Depression was assessed during a clinical interview using Mini-International Neuropsychiatric Interview and the 10-item, clinician-administered, Montgomery-Asberg Depression Rating Scale. From a cohort of 100 massively obese patients, we selected 33 of them for transcriptomic analysis. Twenty-four of them were again analyzed 4-12 months after bariatric surgery. We conducted differential gene expression analyses before and after surgery in unmedicated MDD and non-depressed obese subjects. We found that TP53 (Tumor Protein 53), GR (Glucocorticoid Receptor), and NFκB (Nuclear Factor kappa B) pathways were the most discriminating pathways associated with inflammation-related MDD. These signaling pathways were processed in composite z-scores of gene expression that were used as biomarkers in regression analyses. Results showed that these transcriptomic biomarkers highly predicted depressive symptom intensity at baseline and their remission after bariatric surgery. While inflammation was present in all patients, GR signaling over-activation was found only in depressed ones where it may further increase inflammatory and apoptosis pathways. In conclusion, using an original model of inflammation-related depression and its remission without antidepressants, we provide molecular predictors of inflammation-related MDD and new insights in the molecular pathways involved.