The effect of norepinephrine on insulin secretion and glucose effectiveness in non-insulin-dependent diabetes

Fasting for 48 h induced similar glucose intolerance in both sexes despite greater perceived stress and decreased estradiol levels in females

PURPOSE

The purpose of this study was to compare the effects of fasting for 48 h on the evoked insulin and glucose responses in males and females, and to explore factors such as stress and estrogen levels that might influence these responses.

METHODS

Healthy, nonobese male (n = 14) and female (n = 14) subjects underwent 48-h fasting trial. Changes in glucose tolerance and insulin levels in response to the oral glucose tolerance test, subjectively perceived stress and catecholamine concentrations were measured in all participants. Estrogen levels were also measured in the female participants during the 48-h fast.

RESULTS

Glucose area under the curve (AUC) values increased similarly in both sexes after 48-h fasting (P < 0.05), but females displayed a greater rise in insulin AUC values than males (P < 0.05). Fasting increased plasma epinephrine concentrations in both sexes (P < 0.05), whereas plasma norepinephrine concentrations and subjective stress increased only in females (P < 0.05). Plasma 17-β-estradiol concentrations in females decreased after fasting (P < 0.05).

CONCLUSION

Fasting for 48 h induced a similar glucose intolerance in females and males, despite decreased 17-β-estradiol levels and greater psychological and physiological stress in females. These differences represent a plausible explanation for the gender-based differences observed in insulin responses.

TRIAL REGISTRATION

Retrospectively registered on ClinicalTrials.gov (NCT05545943) in September 19, 2022.

Sustained chemogenetic activation of locus coeruleus norepinephrine neurons promotes dopaminergic neuron survival in synucleinopathy

Dopaminergic neuron degeneration in the midbrain plays a pivotal role in motor symptoms associated with Parkinson's disease. However, non-motor symptoms of Parkinson's disease and post-mortem histopathology confirm dysfunction in other brain areas, including the locus coeruleus and its associated neurotransmitter norepinephrine. Here, we investigate the role of central norepinephrine-producing neurons in Parkinson's disease by chronically stimulating catecholaminergic neurons in the locus coeruleus using chemogenetic manipulation. We show that norepinephrine neurons send complex axonal projections to the dopaminergic neurons in the substantia nigra, confirming physical communication between these regions. Furthermore, we demonstrate that increased activity of norepinephrine neurons is protective against dopaminergic neuronal depletion in human α-syn A53T missense mutation over-expressing mice and prevents motor dysfunction in these mice. Remarkably, elevated norepinephrine neurons action fails to alleviate α-synuclein aggregation and microgliosis in the substantia nigra suggesting the presence of an alternate neuroprotective mechanism. The beneficial effects of high norepinephrine neuron activity might be attributed to the action of norepinephrine on dopaminergic neurons, as recombinant norepinephrine treatment increased primary dopaminergic neuron cultures survival and neurite sprouting. Collectively, our results suggest a neuroprotective mechanism where noradrenergic neurons activity preserves the integrity of dopaminergic neurons, which prevents synucleinopathy-dependent loss of these cells.

Potential Therapeutic Targeting Neurotransmitter Receptors in Diabetes

Neurotransmitters are signaling molecules secreted by neurons to coordinate communication and proper function among different sections in the central neural system (CNS) by binding with different receptors. Some neurotransmitters as well as their receptors are found in pancreatic islets and are involved in the regulation of glucose homeostasis. Neurotransmitters can act with their receptors in pancreatic islets to stimulate or inhibit the secretion of insulin (β cell), glucagon (α cell) or somatostatin (δ cell). Neurotransmitter receptors are either G-protein coupled receptors or ligand-gated channels, their effects on blood glucose are mainly decided by the number and location of them in islets. Dysfunction of neurotransmitters receptors in islets is involved in the development of β cell dysfunction and type 2 diabetes (T2D).Therapies targeting different transmitter systems have great potential in the prevention and treatment of T2D and other metabolic diseases.

Noradrenergic fibers are associated with beta-cell dedifferentiation and impaired beta-cell function in humans

AIMS/HYPOTHESIS

Type 2 diabetes (T2D) is characterized by a progressive loss of beta-cell function, and the "disappearance" of beta-cells in T2D may also be caused by the process of beta -cell dedifferentiation. Since noradrenergic innervation inhibits insulin secretion and density of noradrenergic fibers is increased in type 2 diabetes mouse models, we aimed to study the relation between islet innervation, dedifferentiation and beta-cell function in humans.

METHODS

Using immunohistochemistry and electron microscopy, we analyzed pancreata from organ donors and from patients undergoing pancreatic surgery. In the latter, a pre-surgical detailed metabolic characterization by oral glucose tolerance test (OGTT) and hyperglycemic clamp was performed before surgery, thus obtaining in vivo functional parameters of beta-cell function and insulin secretion.

RESULTS

The islets of diabetic subjects were 3 times more innervated than controls (0.91 ± 0.21 vs 0.32 ± 0.10, n.fibers/islet; p = 0.01), and directly correlated with the dedifferentiation score (r = 0.39; p = 0.03). In vivo functional parameters of insulin secretion, assessed by hyperglycemic clamp, negatively correlated with the increase in fibers [beta-cell Glucose Sensitivity (r = -0.84; p = 0.01), incremental second-phase insulin secretion (r = -0.84, p = 0.03) and arginine-stimulated insulin secretion (r = -0.76, p = 0.04)]. Moreover, we observed a progressive increase in fibers, paralleling worsening glucose tolerance (from NGT through IGT to T2D).

CONCLUSIONS/INTERPRETATION

Noradrenergic fibers are significantly increased in the islets of diabetic subjects and this positively correlates with beta-cell dedifferentiation score. The correlation between in vivo insulin secretion parameters and the density of pancreatic noradrenergic fibers suggests a significant involvement of these fibers in the pathogenesis of the disease, and indirectly, in the islet dedifferentiation process.

Norepinephrine protects against apoptosis of mesenchymal stem cells induced by high glucose

In diabetes, the number of bone mesenchymal stem cells (MSCs) decreases and their differentiation is impaired. However, the exact mechanism is unclear. Patients with diabetes often experience sympathetic nerve injury. Norepinephrine (NE), a major mediator of the sympathetic nervous system, influences rat MSC migration in culture and in vivo. The present study aimed to investigate the effect of NE on MSCs under high glucose conditions; therefore MSCs were treated with high glucose and NE. High glucose-induced MSCs apoptosis, which was reversed by NE. To verify the effect of NE, mice underwent sympathectomy and were used to establish a diabetic model. Diabetic mice with sympathectomy had a higher apoptosis rate and higher levels of reactive oxygen species in their bone marrow-derived cells than diabetic mice without sympathectomy. High glucose inhibited p-AKT production and B-Cell CLL/Lymphoma 2 expression, and promoted BAX and caspase-3 expression. NE reversed these effects of high glucose. An AKT inhibitor enhanced the effects of high glucose. Thus, NE had a protective effect on MSC apoptosis induced by high glucose, possibly via the AKT/BCL-2 pathway.

The Effects of Mental Stress on Non-insulin-dependent Diabetes: Determining the Relationship Between Catecholamine and Adrenergic Signals from Stress, Anxiety, and Depression on the Physiological Changes in the Pancreatic Hormone Secretion

Non-insulin-dependent diabetes or type II diabetes is prevalent around the world. A high-fat diet and chronic inactivity are often responsible for this chronic ailment. However, it is suspected that a high level of stress can also exacerbate diabetes. High anxiety can result in the release of sympathetic hormones that can elevate both cortisol and glucose levels, decrease insulin release, or affect the sensitivity and resistant of the insulin hormone. We have analyzed three research articles to see how stress and anxiety can affect non-insulin-dependent diabetes. In the first article, we selected participants with type II diabetes and injected them with saline or norepinephrine. The results indicated that participants with norepinephrine had experienced a decrease in glucose disposal and reduction in insulin secretion rate. Our second article utilizes African-American adults with type II diabetes. We provide them with a survey to determine how stress, anxiety, and depression can affect adherence to lifestyle modifications such as exercise and eating a proper diet. We find that subjects with higher stress levels tend to have lower compliance with their lifestyle regimes. Our third article focuses on female participants and divides them into two categories which are high chronic stress (HCS) and low chronic stress (LCS). We use an MRI to observe their brain activity while they stare at a picture of high-caloric type food. Our results indicate that there are different responses in various brain structure activities between subjects with HCS and LCS group. With these analyses, it can improve on the way healthcare providers can consult with their patients who have exacerbated type II diabetes despite proper medication and lifestyle modification.

Antidepressant continuation in pregnancy and risk of gestational diabetes

PURPOSE

Previous studies observed modestly higher risk of gestational diabetes (GDM) associated with antidepressant use in pregnancy, potentially due to confounding by indication. We assessed the association of antidepressant continuation in pregnancy with GDM, as well as blood glucose levels, after accounting for confounding.

METHODS

We conducted a retrospective cohort study of singleton live births from 2001 to 2014 to women enrolled in Kaiser Permanente Washington, an integrated health care delivery system, utilizing electronic health data and linked Washington State birth records. We required that women have ≥1 antidepressant prescription fills ≤6 months before pregnancy. Women with an antidepressant fill during pregnancy were categorized as "continuers" (n = 1634); those without a fill were "discontinuers" (n = 1211). We calculated relative risks (RRs) for GDM and mean differences in screening blood glucose levels using generalized estimating equations with inverse probability of treatment weighting to account for baseline characteristics, including mental health conditions and indicators of mental health severity.

RESULTS

Compared with discontinuers, antidepressant continuers had comparable risk of GDM (RR: 1.10; 95% confidence interval [CI], 0.84-1.44) and blood glucose levels (mean difference: 2.3 mg/dL; 95% CI, -1.5 to 6.1 mg/dL). We observed generally similar results for specific antidepressants, with the potential exceptions of risk of GDM associated with sertraline (RR: 1.30; 95% CI, 0.90-1.88) and venlafaxine (RR: 1.52; 95% CI, 0.87-2.68), but neither association was statistically significant.

CONCLUSIONS

Our study suggests that overall, women who continue antidepressants in pregnancy are not at increased risk for GDM or higher blood glucose, although further study may be warranted for sertraline and venlafaxine.

Diabetes hospitalizations and deaths in a cohort of treatment-seeking illicit drug users

Background:

Studies on diabetes among illicit drug users are scarce in Finland. This study aimed to describe hospitalization and death due to diabetes among treatment-seeking illicit drug users.

Methods:

Information of 4817 treatment-seeking drug users (3365 men and 1452 women) aged 11–65 years (mean 24.5 years) was linked to the Finnish national hospital discharge register and the national death registry to identify those clients who were hospitalized or died from diabetes mellitus during 1997–2013.

Results:

Fifty-three persons (42 men and 11 women) had primary diagnoses of diabetes, with a total of 146 hospitalizations (121 among men and 25 among women). The total length of stay among men (1183 days) far exceeded those of women (138 days). Overall, type 1 diabetes was the main contributor to hospitalizations (67%, n = 98/146). The proportion of Type 1 diabetes with complications was 31% in men (n = 37/121) and 44% in women (n = 11/25). All cases of deaths due to diabetes (n = 7) occurred in men.

Conclusion:

Diabetes hospitalizations were mainly due to Type 1 diabetes. Longer length of hospital stay was observed in men, and all diabetes deaths occurred among men. Male drug users and drug users in general would require more support to reduce morbidity and mortality due to diabetes.

Adrenergic and noradrenergic regulation of poultry behavior and production

Norepinephrine and epinephrine (noradrenaline and adrenaline) are integral in maintaining behavioral and physiological homeostasis during both aversive and rewarding events. They regulate the response to stressful stimuli through direct activation of adrenergic receptors in the central and sympathetic nervous systems, hormonal activity and through the interaction of the brain, gut, and microbiome. The multiple functions of these catecholamines work synergistically to prepare an individual for a "fight or flight" response. However, hyper-reactivity of this system can lead to increased fearfulness and aggression, decreased health and productivity, and a reduction in overall well-being. Behaviors, such as aggression and certain fear-related behaviors, are a serious problem in the poultry industry that can lead to injury and cannibalism. For decades, catecholamines have been used as a measure of stress in animals. However, few studies have specifically targeted the adrenergic systems as means to reduce behaviors that are damaging or maladapted to their rearing environments and improve animal well-being. This article attempts to address our current understanding of specific, adrenergic-regulated behaviors that impact chicken well-being and production.

An Experimental Analysis of the Catecholamines in Hyperglycemia and Acidosis-Induced Rat Brain

Hyperglycemia and acidosis are the hallmarks of diabetes. Since these factors play an important role in diabetic complications, we have studied the brain catecholamine levels in hyperglycemic and acidotic conditions per se. Experimentally induced hyperglycemia and acidosis are accompanied by significant alterations in the catecholamine levels in discrete areas of the brain. We and others have shown that chronic or acute diabetes in animals, as well as in humans results in altered neurotransmitter levels. In the present study, hyperglycemia maintained by daily external administration of glucose for thirty days showed increased level of dopamine in striatum and hippocampus, elevation of norepinephrine in hippocampus, and increased level of epinephrine in hypothalamus, midbrain and pons medulla. The ammonium chloride induced acidosis demonstrated significant elevation of dopamine in midbrain and significant increase of norepinephrine in hypothalamus and midbrain, and increased level of epinephrine in hypothalamus, pons medulla and cerebral cortex. On the other hand, sodium acetoacetate induced acidosis did not show any significant change in the level of catecholamines in any of the areas studied. In conclusion, the changes in catecholamine levels observed in experimentally induced hyperglycemic as well as in acidotic conditions are closely related to the changes observed in spontaneous or alloxan or streptozotocin diabetic animals, thereby suggesting that these conditions may be responsible for the changes observed in diabetic animals.

Managing young people with Type 1 diabetes in a 'rave' new world: metabolic complications of substance abuse in Type 1 diabetes

The taxing transition from adolescence towards adulthood intensifies the impact of a chronic illness such as Type 1 diabetes. It is not uncommon for young people with Type 1 diabetes to use recreational drugs for emotional relief to escape the day-to-day burden of chronic disease. Despite increasing use, especially in the setting of 'rave' parties, there is professional lack of understanding of the impact of recreational drug use on glycaemia and metabolic complications. The current review describes the prevalence of substance abuse in Type 1 diabetes and the acute impact of designer drugs on its management. We propose a practical approach to improve care of young people with Type 1 diabetes using designer drugs.

Application of the intravenous glucose tolerance test and the minimal model to patients with insulinoma: insulin sensitivity (Si) and glucose effectiveness (Sg) before and after surgical excision

BACKGROUND

The unmodified frequently sampled intravenous glucose tolerance test (FSIGT) has not previously been used to assess insulin/glucose kinetics in patients with insulinoma.

OBJECTIVE

To measure insulin sensitivity (Si) and glucose effectiveness (Sg) by means of the FSIGT in patients with insulinoma, before and after surgical removal of the tumour.

SUBJECTS AND METHODS

FSIGTs were performed in five patients, before and approximately 3 months post-surgery, and in 11 controls. Si and Sg were estimated using Minimal Model computer analysis of dynamic glucose and insulin data.

RESULTS

Si was lower in insulinoma patients before, compared with after surgery (3.37 +/- 0.62 vs. 6.24 +/- 1.09 SE [x10(-4)] min(-1)microU(-1) ml, P < 0.05). Sg was similar in patients pre- and post-surgery (3.0 +/- 0.67 vs. 2.4 +/- 0.6 [x10(-2)] min(-1), NS).

CONCLUSIONS

Insulin sensitivity improves after excision of an insulinoma. Glucose effectiveness is not influenced by chronic hyperinsulinaemia and hypoglycaemia.

An acute hyperglycemia or acidosis-induced changes of indolamines level correlates with PKC-alpha expression in rat brain

Hyperglycemia and ketoacidosis are the two most serious factors in acute metabolic complications of both type 1 and type 2 diabetes. Dysfunction of the central nervous system is a well-documented complication of diabetes. We and others have previously reported that acute or chronic diabetes in animal's results in altered brain neurotransmitter levels. In this study, we investigated the effects of acute (7 days) glucose-induced hyperglycemia and sodium acetoacetate (NaAcAc) or ammonium chloride (NH4Cl) induced acidosis on the level of indolamines (5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA)) as well as PKC-alpha expression/activity in discrete areas of rat brain. Glucose-induced (500 mg/kg, bw) hyperglycemic ( approximately 249 mg%) rats showed significant (p<0.05) increase in 5-HT levels in mid brain (MB), pons medulla (PM) and cerebellum (CB), respectively. 5-HIAA level increased in hippocampus (HC) (p<0.05) as compared to control. The rats treated with sodium acetoacetate (NaAcAc) for 7 days (60 mg/kg, bw) showed significant decrease (p<0.05) of 5-HT level in hypothalamus (HT). Whereas, the 5-HIAA level increased in MB (p<0.05). Similarly, the PKC-alpha expression as well as the enzyme activity showed significant increase in HC, MB, PM and CB under glucose-induced hyperglycemia and that changes correlated the changes of indolamines, suggesting that the hyperglycemia may be the major metabolic disorder in diabetic complications.

Involvement of Ca2+/calmodulin-dependent protein kinase II in the modulation of indolamines in diabetic and hyperglycemic rats

Hyperglycemia and acidosis are the key factors in diabetic complications. It has been shown that acute or chronic diabetes alters serotonin levels in brain. However, the mechanism of hyperglycemia- or acidosis-induced changes in serotonin levels remains poorly understood. Because Ca2+-dependent protein kinases play a major role in the regulation of serotonin synthesis and release, we investigated the effect of diabetes, hyperglycemia, and acidosis on the level of indolamines [5-hydroxytryptamine (5-HT) and/or 5-hydroxyindoleacetic acid (5-HIAA)] and Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) enzyme activity or protein expression in different brain regions. Alloxan-induced (45 mg/kg bw) diabetic rats (30 days) showed increased level of 5-HT in striatum (ST; 183%), midbrain (MB; 199%), pons medulla (PM; 151%), cerebellum (CB; 214%), and cerebral cortex (CCX; 162%) compared with control (P < 0.05), and these changes were reversed after insulin administration. Rats treated with glucose (500 mg/kg bw) for 30 days showed a 146%, 183%, 208%, and 177% (P < 0.05) increase in 5-HT levels in ST, PM, CB, and CCX, respectively. 5-HIAA level increased in hippocampus (HC; 172%) and in MB (145%; P < 0.05). In addition, rats treated with sodium acetoacetate (NaAcAc) for 30 days (60 mg/kg bw) showed significant increases (P < 0.05) of 5-HT level in ST (152%) and MB (174%). However, the levels of 5-HIAA increased only in MB (151%, P < 0.05). Rats treated with NH4Cl, which induced acidosis (150 mg/kg bw), showed an increased level of 5-HT only in HC (165%, P < 0.05). The increased activity and protein expression of CaMKII in ST, MB, PM, CB, and CCX under diabetic conditions were correlated with the levels of indolamines changes during diabetic, hyperglycemic, or acidotic conditions. These results suggest that CaMKII may be involved in the regulation of indolamines in diabetic animals.

Atypical antipsychotic agents and increased risk of diabetes: class action or differential action?

Atypical antipsychotic (AAP) agents are useful in treating patients with schizophrenia and other psychosis. Their advantages are the low incidence of extrapyramidal side effects, and possible amelioration of negative, cognitive and mood symptoms. Occurrence of diabetes after AAP drug administration is of concern as patients do not often recognise their symptoms, physicians may fail to diagnose early, with consequent morbidity and mortality. The symptoms of psychosis, including lack of insight and motivation, may decrease the ability of schizophrenic patients to communicate potential health problems. Whether or not AAP drugs induce diabetes and, if they do, if it is a class action or a differential action, is often debated. Clinical evidence on AAP drug-induced diabetes is mounting. With their discontinuation, the diabetes often dissipates, but reappears when they are started again, thereby implicating the AAP drugs in the development of diabetes. There is still dispute regarding the differential effect of the various AAP drugs in their ability to produce diabetes. Although not scientifically proven, available evidence seems to indicate that clozapine and olanzapine may have a higher propensity to induce diabetes compared with other AAP drugs.

Effects of pharmacological doses of 2-deoxyglucose on plasma catecholamines and glucose levels in patients with schizophrenia

RATIONALE

Several lines of evidence suggest that the pathophysiology of schizophrenia may be associated with altered noradrenergic and glucoregulatory function.

OBJECTIVE

The aim of this study was to investigate these alterations during a perturbed homeostatic state.

METHODS

Fifteen patients with schizophrenia and 13 healthy individuals were given a glucose deprivation challenge through administration of pharmacological doses of 2-deoxyglucose (2DG; 40 mg/kg), and their plasma was assayed over the next 60 min for concentrations of norepinephrine (NE), the intraneuronal NE metabolite dihydroxyphenylglycol (DHPG), epinephrine and glucose.

RESULTS

2DG induced significant increases in plasma NE, epinephrine and glucose levels in both groups with significantly greater NE and glucose increments in patients than in controls. For DHPG, 2DG produced increases in patients and decreases in the control subjects. NE responses correlated positively and significantly with the DHPG and glucose responses in schizophrenics, but not in controls.

CONCLUSIONS

These findings suggest that patients with schizophrenia have exaggerated NE and glucose responses to an acute metabolic perturbation.

Treatment of depression in comorbid medical illness

The rate of comorbid depression and medical illness varies from 10 to 40%. Over the years, there has been a paucity of studies completed despite the importance of knowing which antidepressants are the most effective and safest to use in comorbid states. In this review, focus is placed on disorders in these important areas: cardiovascular disease, neurological disorders, diabetes mellitus and cancer. Cardiovascular disease complications can be related in many cases to platelet clumping produced by medications; reductions in morbidity can be achieved by reducing platelet adhesiveness. Specific results have shown sertraline administration to be safe in the post myocardial infarction (MI) state. This is a time of depression-induced increases of 200-300% in mortality. Evidence for safe administration of bupropion, as well as the selective serotonin re-uptake inhibitors (SSRIs) fluoxetine and paroxetine, is also available. The appearance of major depression and diabetes mellitus has been successfully treated with fluoxetine, sertraline and nortriptyline (NTI), however, NTI may lead to a worsening of glucose indices due to its noradrenergic specificity. Regarding neurologic disorders, there is controlled data showing the safety and efficacy of citalopram, sertraline and fluoxetine in post stroke depression. Parkinson's disease has been associated frequently with depression, as might be expected from its characteristic dopamine deficient state. For perhaps the same reason, the agents that can block re-uptake of dopamine i.e., tricyclic antidepressants (TCAs), have been effective in comorborbid depression with Parkinson's disease. In dementia, there is a paucity of information on new agents. However, double-blind data seems to show efficacy for sertraline, paroxetine and citalopram. There are few studies of cancer-related depression treated in a controlled fashion with antidepressants; imipramine, amitriptyline, fluoxetine, paroxetine, mirtazapine and mianserin (not available in the USA) all have support from some published studies.