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.

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.

LC-MSMS assays of urinary cortisol, a comparison between four in-house assays.

BACKGROUND: Twenty-four hour urinary free cortisol (UFC) determination can be used for screening and follow-up of Cushing syndrome (CS). As immunoassay methods lack specificity for UFC measurement, the use of high-performance liquid chromatography coupled to mass spectrometer (LC-MSMS) is recommended. The aim of our study was to compare UFC results using four LC-MSMS methods performed in four independent laboratories in order to evaluate interlaboratory agreement. METHODS: Frozen aliquots of 24-h urine samples (78 healthy volunteers and 20 patients with CS) were sent to four different laboratories for analysis. Following liquid-liquid or solid-liquid extraction, UFC were determined using four different LC-MSMS assay. RESULTS: UFC intra- and interassays variation coefficients were lower than 10% for each centre. External quality control results were not significantly different. UFC normal ranges (established from healthy volunteers) were 17-126, 15-134, 12-118 and 27-157 nmol/day, respectively. Classification of UFC from healthy volunteers and patients with CS using a 95th percentile threshold was similar. However, for extreme UFC values (<50 or >270 nmol/day), negative or positive bias was noted. CONCLUSIONS: Even for highly specific methods such as LC-MSMS, variations of results can be found depending on analytical process. Validation of LC-MSMS methods including determination of the reference range is essential.

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.

Urinary glucocorticoid metabolites: biomarkers to classify adrenal incidentalomas?

OBJECTIVE: Total urinary cortisol metabolites represent cortisol production and metabolism. We hypothesized that to assay metabolites could add some information to the one provided by a sole cortisol assay. DESIGN AND PATIENTS: We set up an inexpensive multiplex mass spectrometry assay to quantify cortisol metabolites. We investigated 43 patients with benign secreting (AT+) or silent (AT-) adrenal tumours compared to 48 lean (Nl) or 143 obese (Ob) subjects, and to 26 patients with a Cushing's disease (CD). The initial investigation included immunoreactive quantification of urinary free cortisol (UFC). RESULTS: Cortisol metabolites were overexcreted in CD but not in Ob subjects. Nl and Ob were thus pooled in a control population (Ctl). Cortisol, tetrahydrocortisol (THF) and tetrahydrocortisone (THE) excretions were significantly increased in AT compared to Ctl subjects, whereas immunoreactive UFC was similar. A logistic regression retaining cortisol, THF, and α- and ß-cortolone as significant analytes allowed the construction of a receiver-operating characteristics (ROC) curve significantly better than the curve generated by cortisol alone (area under the curve (AUC) 0·927 vs 0·729, respectively; P < 0·0001). More importantly, although there was no significant difference between Ctl vs AT- subjects for cortisol metabolites, a logistic regression retaining cortisol, allo-THF, and α- and ß-cortolone as significant analytes generated a ROC curve performing significantly better than cortisol alone (AUC 0·910 vs 0·635, respectively; P < 0·0001). CONCLUSION: Cortisol metabolite excretion is modified in AT, including AT-, patients even without modification of UFC. Clinical usefulness of these biomarkers has to be investigated in prospective studies following up patients with AT.

Different methods to estimate serum free cortisol: a comparison during cortisol tetracosactide testing.

BACKGROUND: Serum cortisol is routinely quantified by immunoassays. In intensive care units serum free cortisol (FC) determination has been described as a better indicator of survival than total cortisol (TC). To estimate FC different methods are available including saliva sampling. We compared five methods to estimate FC, before and after an ACTH stimulating test in patients suspected of adrenal insufficiency. METHOD: Serum and saliva was collected from 130 patients from the Endocrine Department of a university hospital before and after tetracosactide injection for TC determination. FC was estimated: after serum ultrafiltration, quadratic (Coolens') or cubic (Dorin's) equations, using TC/cortisol-binding globulin concentrations ratio or using cortisol concentration determination in saliva. RESULTS: FC concentrations obtained by different techniques were significantly correlated and Passing-Bablok regressions showed no deviation from linearity between salFC and filtFC or quadFC. Using the routine assumption that the patients were correctly diagnosed using a post-tetracosactide TC threshold of 550 nmol/L the FC methods generating the best ROC curves were salFC and filtFC or cubFC 30 min after tetracosactide injection. CONCLUSIONS: FC concentrations obtained by different techniques are significantly but not similarly correlated with TC. As, salFC and filtFC are more convenient to perform than methods involving CBG assays and are better correlated to TC during tetracosactide tests they may be preferred as FC surrogate assays.

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.

Acute Effect of a Saffron Extract (Safr'InsideTM) and Its Main Volatile Compound on the Stress Response in Healthy Young Men: A Randomized, Double Blind, Placebo-Controlled, Crossover Study.

According to animal studies, saffron and its main volatile compound safranal may reduce biological and behavioral signs of acute stress. However, little is known about its impact in humans. This study investigated the acute effect of a saffron extract and safranal on the biological and psychological stress responses in healthy men experiencing a laboratory stress procedure. In this double-blind, placebo-controlled, randomized, cross-over study, 19 volunteers aged 18-25 received a single dose of 30 mg saffron extract (Safr'InsideTM), 0.06 mg synthetic safranal, or a placebo on three visits separated by a 28-day washout. Thirteen minutes after administration, participants were exposed to the Maastricht acute stress test (MAST). Salivary cortisol and cortisone were collected from 15 min before the MAST (and pre-dose), 3 min before the MAST, and then 15, 30, 45, 60, and 75 min after the MAST, and stress and anxiety were measured using visual analogic scales. Compared to the placebo, stress and anxiety were significantly toned down after Safranal and Safr'InsideTM administration and coupled with a delay in the times to peak salivary cortisol and cortisone concentrations (p < 0.05). Safr'InsideTM and its volatile compound seem to improve psychological stress response in healthy men after exposure to a lab-based stressor and may modulate the biological stress response.

Evidence of Persistent Mild Hypercortisolism in Patients Medically Treated for Cushing Disease: the Haircush Study.

CONTEXT: Cortisol-lowering drugs may not restore a normal cortisol secretion in Cushing disease (CD). OBJECTIVE: This work aimed to assess the long-term cortisol exposure in medically treated CD patients using hair-cortisol (HF) and hair-cortisone (HE) measurement. METHODS: This multicenter prospective study included 3 groups of female patients: CushMed = 16 treated with a stable cortisol-lowering drug dosage and normal urinary free cortisol (UFC); CushSurg = 13 cured by pituitary surgery; CushBla = 15 receiving stable recommended doses of hydrocortisone following bilateral adrenalectomy. Patients were evaluated for 3 months with their usual treatments. Two late-night saliva and 24-hour urine samples were collected monthly in CushMed, and at study end in CushSurg and CushBla patients. A 3-cm hair sample was collected at study end from all patients. Main outcome measures included clinical score and centralized measurement of UFC, late-night salivary cortisol (LNSF), late-night salivary cortisone (LNSE), HE, HF. RESULTS: Despite having almost all UFCs normalized, CushMed patients exhibited increased HE as compared to CushSurg controls (P = .003). CushMed patients also had increased clinical score (P = .001), UFC (P = .03), LNSF, LNSE (P = .0001), and variability in the latter parameters (P = .004). CushBla patients had increased HF and HE, contrasting with LNSEs similar to CushSurg patients. Six of 15 CushMed patients exhibited increased HE concentrations and had increased antihypertensive drug dosage compared to CushMed patients with normal HE (P = .05). CONCLUSION: Despite normalized UFCs, a subset of medically treated CD patients displays an altered circadian rhythm of serum cortisol. A single HE measurement identifies chronic mild persistent hypercortisolism and could replace multiple saliva analyzes to monitor medical treatments in CD patients once UFC is normalized.

Impact of the reference values on the clinically-relevant cut-offs. The example of cortisol testing in children.

BACKGROUND: After modification of our routine cortisol assay, we questioned the reference ranges for basal and stimulated cortisol plasma concentration in children. METHODS: We retrospectively addressed the relevance of using the manufacturer's normal reference range for basal cortisol and investigated its response to glucagon-betaxolol testing. RESULTS: Basal morning cortisol was 260 (98-604) nmol/L [manufacturer's normal range (185-624) nmol/L: 26% subjects had "low" basal cortisol]. Upon testing cortisol increased to 502 (117-856) nmol/L. If a recently described 100% specificity threshold (403 nmol/L) is used it would amount to 31% adrenal insufficient children in apparently unaffected children. Basal and stimulated cortisol obtained with our prior radioimmunoassay (RIA) in a sub-group of subjects were lower: 411 (187-1061) and 770 (329-1542) nmol/L. Using the 403 nmol/L threshold with the radioimmunoassay would result in only 5% adrenal insufficient children. CONCLUSIONS: This shows again that laboratories have to advertise the need to establish reference values for given populations, both for basal or stimulated hormone levels. Failure to apply this rule will elicit false-positive and more critically, false-negative results.

Adrenal BORDeAux reGistry: Bordeaux single-center study of hypertensive patients with primary hyperaldosteronism.

BACKGROUND: Primary aldosteronism is responsible for a major cardiovascular risk that can be avoided by specific treatment. A better characterization of the hypertensive population with primary aldosteronism would not only improve the overall diagnosis but also allows a better selection of patients requiring adrenal vein sampling (AVS). METHODS: Creation of a prospective single-center Bordeaux ABORDAGE study of hypertensive patients with primary aldosteronism who underwent AVS. Primary aldosteronism was diagnosed according to the recommendations of the SFE/SFHTA. Peripheral and central blood pressure measurements were performed with mercury sphygmomanometer, SphygmoCor applanation tonometer and ambulatory blood pressure measurement. An adrenal computed tomography and an unstimulated AVS were performed in each patient. RESULTS: One hundred and eighty-eight patients were included in our study. They were mostly men (61.7%), with a mean age of 48.7 ±â€Š10.5 years, BMI of 29.7 ±â€Š5 kg/ m2 and duration of hypertension of 101.5 ±â€Š84 months. AVS was selective in 82.3% of patients and lateralization was concordant with CT in only 35.4% of patients. Lateralized secretion was significantly associated with a marked biological primary aldosteronism and hypertension. In multivariate analysis, no variable specifically differentiated patients with aldosterone lateralization. CONCLUSION: The ABORDAGE population description is consistent with the data found in the literature. These characteristics are ultimately those expected in essential hypertension population, which therefore, could explain part of the underdiagnosis of primary aldosteronism. Only AVS is able to predict the lateralization of secretion with a post adrenalectomy recovery of about 90% in case of lateralization. The generalization of AVS would, therefore, increase the proportion of patients with primary aldosteronism cured.

[About a case of macro-FSH analytical interference]. / Une grosse FSH qui trompe énormément : à propos d'un cas de macro-FSH.

An 18-year-old woman was referred by her GP to the endocrinology department of the University Hospital of Bordeaux on suspicion of premature ovarian failure because of a disorder of the menstrual cycle and pathological results of biological exploration of the gonadotropic axis. Repeatedly-found elevated concentrations of FSH contrasted with a normal concentration of LH leading to a hypothesis of ovarian failure. However, different investigations favoured an analytical interference. The presence of heterophilic antibodies or anti-mouse antibodies (HAMA) was unlikely but, finally, a complex combining FSH and autoantibody (called macro-FSH) was evidenced.

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.

Hair cortisol and cortisone measurements for the diagnosis of overt and mild Cushing's syndrome.

OBJECTIVE: Hair cortisol (HF) and cortisone (HE) measurements reflect tissular exposure to cortisol over months and are increased in overt Cushing's syndrome (CS). No data is available in mild CS. We compared the diagnostic performance of HF and HE between patients with overt or mild CS. DESIGN: Single centre retrospective study. METHODS: HF&HE were measured by LC-MS/MS in 48 consecutive adult females with Cushing's disease (CD), ectopic ACTH syndrome, secreting adenomas and carcinomas, and adrenal incidentalomas. All had impaired dexamethasone suppression tests. Overt CS (n = 25) was diagnosed in front of specific symptoms, a mean UFC (>1.5 ULN) and increased midnight serum cortisol or salivary cortisol. Mild CS (n = 23) was diagnosed in patients lacking specific symptoms and displaying at least one additional biological abnormality including mildly increased UFC (≤1.5 ULN), increased midnight serum cortisol or salivary cortisol and suppressed plasma ACTH in patients with adrenal tumours. In this study, 84 healthy subjects and obese patients served as controls. RESULTS: HF and HE showed roughly similar performance in overt CS (92 and 100% sensitivity, 91 and 99% specificity, respectively). HF and HE were lower in mild CS but higher than in controls (P < 0.01). HE was correlated with midnight serum cortisol (P < 0.02) and volume of adrenal incidentalomas (P < 0.04) but not with UFC. HF and HE had 59% and 68% sensitivity, and 79 and 94% specificity, respectively, for the diagnosis of mild CS. Contrary to UFC, both HF and HE were in the range of overt CS in 11/23 patients with mild CS. Patients with mild CS and increased HE required more antihypertensive treatments and showed worser lipid profiles than patients with normal HE. CONCLUSIONS: HF and HE measurement performed better in overt than in mild CS but is a useful adjunct to diagnose mild CS and to identify adrenocortical incidentalomas responsible for excessive cortisol exposure.

What do you need to know about mass spectrometry? A brief guide for endocrinologists.

In routine hormonology, liquid chromatography mass spectrometry (LCMS) is now an established technique for androgen, urinary cortisol and metanephrine assay. It has the undeniable advantage of great analytical specificity, but with sensitivity that clearly depends on financial investment in a very high-end spectrometer. We describe the general principles of LCMS and the routine applications so far developed in hormonology. The purpose is to familiarise endocrinologists with the techniques under development and their pros and cons.

[What to do in the event of a suspicion of analytical interference during an immunoassay?] / Conduite à tenir devant une suspicion d'interférence analytique lors d'un immunodosage.

Identifying analytical interference is a challenge for the medical biologist in providing advice to the prescriber. Indeed, these analytical interferences often have deleterious consequences on the care of patients. Understanding their mechanisms and mastering corrective procedures is essential to limit these management errors. Faced with the many questions from clinicians in current practice, we propose an algorithm for managing a sample when interference is suspected.

Effects of Saffron Extract Supplementation on Mood, Well-Being, and Response to a Psychosocial Stressor in Healthy Adults: A Randomized, Double-Blind, Parallel Group, Clinical Trial.

Anxiety, stress, and low mood are closely related and may contribute to depressive symptoms. Among non-pharmacological solutions to improve subclinical mood symptoms and resilience to stress, natural products such as saffron-identified as promising following preliminary beneficial effects in major depressive disorder-represent a relevant strategy. This study aimed to assess the efficacy of 8 weeks' supplementation with 30 mg standardized saffron extract on emotional well-being in healthy adults with subclinical feelings of low mood and anxiety and/or stress and evaluate the acute effect of saffron in response to a lab-based psychosocial stressor. The study adopted a double-blind, randomized, parallel groups design in which 56 healthy male and female individuals (18-54 years) received either a saffron extract or a placebo for 8 weeks. Chronic effects of saffron on subjective anxiety, stress, and depressive feelings were assessed using a questionnaire battery [including Profile of Mood State-2, (POMS)] and acute effects in response to a lab-based psychosocial stressor were measured through psychological and physiological parameters. Urinary crocetin levels were quantified. Participants who received the saffron extract reported reduced depression scores and improved social relationships at the end of the study. Urinary crocetin levels increased significantly with saffron supplementation and were correlated with change in depression scores. The typical stress-induced decrease in heart rate variability (HRV) during exposure to the stressor was attenuated following acute saffron intake. Saffron extract appears to improve subclinical depressive symptoms in healthy individuals and may contribute to increased resilience against the development of stress-related psychiatric disorders. Clinical trials number: NCT03639831.

Disruption of gap junctions attenuates acute myeloid leukemia chemoresistance induced by bone marrow mesenchymal stromal cells.

The bone marrow (BM) niche impacts the progression of acute myeloid leukemia (AML) by favoring the chemoresistance of AML cells. Intimate interactions between leukemic cells and BM mesenchymal stromal cells (BM-MSCs) play key roles in this process. Direct intercellular communications between hematopoietic cells and BM-MSCs involve connexins, components of gap junctions. We postulated that blocking gap junction assembly could modify cell-cell interactions in the leukemic niche and consequently the chemoresistance. The comparison of BM-MSCs from AML patients and healthy donors revealed a specific profile of connexins in BM-MSCs of the leukemic niche and the effects of carbenoxolone (CBX), a gap junction disruptor, were evaluated on AML cells. CBX presents an antileukemic effect without affecting normal BM-CD34+ progenitor cells. The proapoptotic effect of CBX on AML cells is in line with the extinction of energy metabolism. CBX acts synergistically with cytarabine (Ara-C) in vitro and in vivo. Coculture experiments of AML cells with BM-MSCs revealed that CBX neutralizes the protective effect of the niche against the Ara-C-induced apoptosis of leukemic cells. Altogether, these results suggest that CBX could be of therapeutic interest to reduce the chemoresistance favored by the leukemic niche, by targeting gap junctions, without affecting normal hematopoiesis.

Correction: Disruption of gap junctions attenuates acute myeloid leukemia chemoresistance induced by bone marrow mesenchymal stromal cells.

The original version of this Article omitted the following from the Acknowledgements: This research was also supported by grants to KZ (UL and L-CNRS). This has now been corrected in both the PDF and HTML versions of the Article.

Insulin treatment partially prevents cognitive and hippocampal alterations as well as glucocorticoid dysregulation in early-onset insulin-deficient diabetic rats.

The diagnosis of Type 1 Diabetes (T1D) in ever younger children led us to question the impact of insulin deficiency or chronic hyperglycemia on cerebral development and memory performances. Here, we sought abnormalities in these traits in a model of streptozotocin-induced diabetes in juvenile rats treated or not by insulin. We made the assumption that such alterations would be related, at least in part, to excessive glucocorticoid exposition in hippocampal neurons. We have compared 3 groups of juvenile rats: controls, untreated diabetics and insulin-treated diabetics. Diabetes was induced by streptozotocin (65 mg/kg IP/day, 2 consecutive days), at postnatal days 21 and 22 and a subcutaneous pellet delivering 2 U of insulin/day was implanted in treated diabetic rats 3 days later. Three weeks after diabetes induction, cognitive performances (Y maze, object location and recognition tests), in vivo brain structure (brain volume and water diffusion by structural magnetic resonance imaging), and hippocampal neurogenesis (immunohistochemical labeling) measurements were undertaken. Corticosterone levels were evaluated in plasma under basal and stress conditions, and within hippocampus together with 11ß-dehydrocorticosterone to assess 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) activity. The comparison of the three experimental groups revealed that, compared to controls, untreated diabetic rats showed decreased cognitive performances in Y-maze and object location test (p < 0.05), decreased brain and hippocampal microstructure (p < 0.05), and decreased maturation and survival of hippocampal newborn neurons (p < 0.05). These alterations were associated with increased plasma corticosterone at the baseline nadir of its secretion (p < 0.001) and during the recovery phase following a restraint stress (p < 0.001), as well as increased hippocampal corticosterone levels (p < 0.01) and 11ß-HSD1 activity (p < 0.05). As untreated diabetic rats, insulin-treated diabetic rats displayed decreased brain volume and water diffusion (p < 0.05 compared to controls) and intermediate memory performances and hippocampal neurogenesis (p value not significant compared to either controls or untreated diabetics). Moreover, they were similar to controls for basal plasma and hippocampal corticosterone and 11ß-HSD1 activity but show increased plasma corticosterone during the recovery phase following a restraint stress similar to untreated diabetics (p < 0.001 compared to controls). Thus, insulin did not completely prevent several hippocampal-dependent behavioral and structural alterations induced by diabetes in juvenile rats which may relate to the higher cognitive difficulties encountered in T1D children compared to non-diabetic controls. Although insulin restored basal corticosterone and 11ß-HSD1 activity (in hippocampus and plasma), the negative feedback regulation of corticosterone secretion after stress was still impaired in insulin-treated diabetic rats. Further characterization of insulin control on glucocorticoid regulation and availability within hippocampus is awaited.