Effect of nociceptin on insulin release in normal and diabetic rat pancreas

Perioperative changes of serum orphanin in diabetic patients and its relationship with sympathetic nervous system

The occurrence of cardiovascular events in diabetic patients during the perioperative period is related to the activation of sympathetic nerves. Basic research shows that serum nociceptin/orphanin FQ (N/OFQ) levels in diabetic neuropathy rats increased, and N/OFQ reduces the release of norepinephrine (NE). We hypothesize that N/OFQ will affect the sympathetic nervous system during perioperative myocardium of diabetic patients. 66 patients with unilateral knee arthroplasty were divided into diabetes group (D group) and non-diabetes group (N group). Measured blood glucose, serum NE, N/OFQ concentrations at the 30 min before anesthesia (T0), 1 h after surgery (T1), 24 h after surgery (T2) and the cardiac troponinI (cTnI) concentration at T0 and T2. Compared with N group, the concentration of blood glucose, N/OFQ and cTnI in D group was higher and the NE was lower at T0 (P < 0.05). At T1, the blood glucose, N/OFQ, NE concentrations of D group increased, only the blood glucose increased in N group (P < 0.05). Serum N/OFQ of D group from T0 to T1 was correlated with the change trend of blood glucose, NE concentration from T0 to T1 and cTnI from T0 to T2(r = 0.386, P = 0.027; r = 0.350, P = 0.046; r = 0.363, P = 0.038). The outcomes demonstrated that the preoperative serum N/OFQ concentration in diabetic patients was increased, and the increase in N/OFQ concentration during the operation was related to the increase in NE and cTnI concentrations, perioperative N/OFQ may mediate myocardial injury through sympathetic nervous system.

Histamine H3 receptor antagonists - Roles in neurological and endocrine diseases and diabetes mellitus

Human histamine H3 receptor (H3R) was initially described in the brain of rat in 1983 and cloned in 1999. It can be found in the human brain and functions as a regulator of histamine synthesis and release. H3 receptors are predominantly resident in the presynaptic region of neurons containing histamine, where they modulate the synthesis and release of histamine (autoreceptor) or other neurotransmitters such as dopamine, norepinephrine, gamma-aminobutyric acid (GABA), glutamate, acetylcholine and serotonin (all heteroreceptors). The human histamine H3 receptor has twenty isoforms of which eight are functional. H3 receptor expression is seen in the cerebral cortex, neurons of the basal ganglia and hippocampus, which are important for process of cognition, sleep and homoeostatic regulation. In addition, histamine H3R antagonists stimulate insulin release, through inducing the release of acetylcholine and cause significant reduction in total body weight and triglycerides in obese subjects by causing a feeling of satiety in the hypothalamus. The ability of histamine H3R antagonist to reduce diabetes-induced hyperglycaemia is comparable to that of metformin. It is reasonable therefore, to claim that H3 receptor antagonists may play an important role in the therapy of disorders of cognition, the ability to sleep, oxidative stress, inflammation and anomaly of glucose homoeostasis. A large number of H3R antagonists are being developed by pharmaceutical companies and university research centres. As examples of these new drugs, this review will discuss a number of drugs, including the first histamine H3R receptor antagonist produced.

Diabetes Mellitus Alters the Immuno-Expression of Neuronal Nitric Oxide Synthase in the Rat Pancreas

Nitric oxide is generated from nitric oxide synthase following hyperglycemia-induced oxidative stress during the course of diabetes mellitus (DM). We examined the temporal immuno-expression of neuronal nitric oxide synthase (nNOS) in the pancreas of diabetic and non-diabetic rats using immunohistochemical, immunofluorescence and western blot techniques 12 h, 24 h, 1 week, 2 weeks, 1, 8 and 15 months after induction of DM. nNOS co-localized with pancreatic beta cells but disappears 12 h after the onset of DM. In contrast, the nNOS content of pancreatic nerves increased significantly (p < 0.001) 24 h after the induction of DM, and decreased sharply thereafter. However, nNOS-positive ganglion cells were observed even 15 months post-diabetes. ROS increased by more than 100% two months after the onset of DM compared to non-diabetic control but was significantly (p < 0.000001) reduced at 9 months after the induction of DM. The pancreatic content of GSH increased significantly (p < 0.02) after 9 months of DM. Although, TBARS content was significantly (p < 0.009; p < 0.002) lower in aged (9 months) non-diabetic and DM rats, TBARS rate was markedly (p < 0.02) higher 9 months after the induction of DM when compared to younger age group. In conclusion, nNOS is present in pancreatic beta cell, but disappears 12 h after the onset of diabetes. In contrast, the tissue level of nNOS of pancreatic nerves increased in the first week of diabetes, followed by a sharp reduction. nNOS may play important roles in the metabolism of pancreatic beta cell.

Nociceptin Increases Antioxidant Expression in the Kidney, Liver and Brain of Diabetic Rats

Simple Summary

Nociceptin (NC) is a small peptide implicated in the physiology of pain, learning and memory. Here we investigated the role of NC in the induction of antioxidants in the kidney, liver, and the brain of diabetic rats using morphological and biochemical methods. Normal and diabetic animals were treated with NC for 5 days. Catalase (CAT) was expressed in the kidney, liver, and the neurons of the brain. Although CAT was markedly (p < 0.05) lower in the tubules of the kidney of normal and diabetic animals after NC treatment, NC significantly (p < 0.001) increased the presence of CAT in the liver and brain of diabetic rats. Superoxide dismutase (SOD) was observed in kidney tubules, hepatocytes, and neurons of the brain. Treatment with NC markedly (p < 0.001) increased the level of SOD in hepatocytes and neurons of the brain. Glutathione reductase (GRED) was seen in the convoluted tubules of the kidney, hepatocytes and neurons of the brain. Treatment with NC markedly increased (p < 0.001) the expression of GRED in kidney tubules, hepatocytes and neurons of the brain. In conclusion, NC can help diabetic patients mitigate the effects of oxidative stress by its ability to induce endogenous antioxidants.

Abstract

Nociceptin (NC) consists of 17 amino acids (aa) and takes part in the processing of learning and memory. The role of NC in the induction of endogenous antioxidants in still unclear. We examined the effect of NC on the expression of endogenous antioxidants in kidney, liver, cerebral cortex (CC), and hippocampus after the onset of diabetes mellitus, using enzyme-linked immunosorbent assay and immunohistochemistry. Exogenous NC (aa chain 1–17; 10 µg/kg body weight) was given intraperitoneally to normal and diabetic rats for 5 days. Our results showed that catalase (CAT) is present in the proximal (PCT) and distal (DCT) convoluted tubules of kidney, hepatocytes, and neurons of CC and hippocampus. The expression of CAT was significantly (p < 0.05) reduced in the kidney of normal and diabetic rats after treatment with NC. However, NC markedly (p < 0.001) increased the expression CAT in the liver and neurons of CC of diabetic rats. Superoxide dismutase (SOD) is widely distributed in the PCT and DCT of kidney, hepatocytes, and neurons of CC and hippocampus. NC significantly (p < 0.001) increased the expression of SOD in hepatocytes and neurons of CC and the hippocampus but not in the kidney. Glutathione reductase (GRED) was observed in kidney tubules, hepatocytes and neurons of the brain. NC markedly increased (p < 0.001) the expression of GRED in PCT and DCT cells of the kidney and hepatocytes of liver and neurons of CC. In conclusion, NC is a strong inducer of CAT, SOD, and GRED expression in the kidney, liver and brain of diabetic rats.

Anti-diabetic Effect of Acridocarpus Orientalis

Background:

Acridocarpus orientalis (AO) is a medicinal herb indigenous to tropical and subtropical Africa, Arabian Peninsula, and New Caledonia with reported anti-inflammatory and antioxidant properties.

Objective:

To determine whether AO has any beneficial effects on diabetes-induced metabolic parameters in rats.

Materials and Methods:

Diabetes mellitus was induced in male Wistar rats by streptozotocin. Diabetic rats were treated with three doses of AO extract (50, 100, and 200 mg/kg BW) for 30 days. Kidney, liver, and pancreatic tissue samples were processed for histopathology to determine the effect of AO on the cells of these organs. The effect of AO on pancreatic islet cells and serum insulin levels was also examined using immunohistochemistry and enzyme-linked immunosorbent assay techniques, respectively.

Results:

AO (100 mg/kg BW) caused a marked reduction in blood glucose levels in diabetic rats compared to diabetic control on day 10 of the study. Moreover, AO (200 mg/kg BW) increased the number of insulin-positive cells with a concomitant reduction in the number of glucagon-immunoreactive cells in pancreatic islets. AO (100 mg/kg) also increased the serum level of superoxide dismutase significantly. Although the administration of AO was able to significantly decrease the diabetes-associated increases in serum creatinine and bilirubin levels, it had no effect on blood urea nitrogen, serum aspartate, or alanine aminotransferase levels. Histopathological examination showed that AO has no toxic effect on the structure of the pancreas, liver, and kidney.

Conclusion:

Our findings showed that AO could alleviate some complications of diabetes mellitus.

Endogenous Opiates and Behavior: 2018

This paper is the forty-first consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2018 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (2), the roles of these opioid peptides and receptors in pain and analgesia in animals (3) and humans (4), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (5), opioid peptide and receptor involvement in tolerance and dependence (6), stress and social status (7), learning and memory (8), eating and drinking (9), drug abuse and alcohol (10), sexual activity and hormones, pregnancy, development and endocrinology (11), mental illness and mood (12), seizures and neurologic disorders (13), electrical-related activity and neurophysiology (14), general activity and locomotion (15), gastrointestinal, renal and hepatic functions (16), cardiovascular responses (17), respiration and thermoregulation (18), and immunological responses (19).

Exogenous Ghrelin Increases Plasma Insulin Level in Diabetic Rats

Ghrelin, a 28-amino acid peptide, is a strong growth hormone secretagogue and a regulator of food intake. In addition, ghrelin is thought to play a role in insulin secretion and in glucose homeostasis. A lot of contradictory data have been reported in the literature regarding the co-localization of ghrelin with other hormones in the islet of Langerhans, its role in insulin secretion and attenuation of type 2 diabetes mellitus. In this study, we investigate the effect of chronic ghrelin treatment on glucose, body weight and insulin level in normal and streptozotocin-induced diabetic male Wistar rats. We have also examined the distribution pattern and co-localization of ghrelin with insulin in pancreatic islet cells using immunohistochemistry and immune-electron microscopy and the ability of ghrelin to stimulate insulin release from the CRL11065 beta cell line. Control, non-diabetic groups received intraperitoneal injection of normal saline, while treated groups received intraperitoneal injection of 5 µg/kg body weight of ghrelin (amino acid chain 24–51) on a daily basis for a duration of four weeks. Our results show that the administration of ghrelin increases the number of insulin-secreting beta cells and serum insulin level in both normal and diabetic rats. We also demonstrated that ghrelin co-localizes with insulin in pancreatic islet cells and that the pattern of ghrelin distribution is altered after the onset of diabetes. Moreover, ghrelin at a dose of 10⁻⁶ M and 10⁻¹² M increased insulin release from the CRL11065 beta cell line. In summary, ghrelin co-localizes with insulin in the secretory granules of pancreatic beta cells and enhances insulin production.

Methionine enkephalin (MENK) regulates the immune pathogenesis of type 2 diabetes mellitus via the IL-33/ST2 pathway

The incidence and mortality of type 2 diabetes mellitus (T2DM) rank among the top ten worldwide. Emerging studies indicate pathological roles for the immune system in inflammation, insulin resistance and islet β-cell damage in subjects with T2DM. Methionine enkephalin (MENK) is present in endocrine cells of the pancreas and has been suggested to be an important mediator between the immune and neuroendocrine systems. Therefore, it may play a role in modulating insulin secretion from islet cells. Since little is known about the effect of MENK on T2DM, therefore it was the aim of this study to characterize the role and possible mechanism of action of MENK on plasma glucose and serum insulin levels in T2DM rats and INS-1 cells in vivo and in vitro. MENK significantly decreased the plasma glucose level and increased the serum insulin concentration in T2DM rats. It also increased the serum levels of the cytokines IL-5 and IL-10, while decreased TNF-α and IL-2 levels. We further confirmed that MENK regulated glucose metabolism by upregulating opioid receptor expression and modulating the IL-33/ST2 and MyD88-TRAF6-NF-κB p65 signaling pathways. Based on these results, an intraperitoneal injection of MENK represents a potentially new approach for T2DM.

Effect of berberine on the HPA-axis pathway and skeletal muscle GLUT4 in type 2 diabetes mellitus rats

PURPOSE

Activation of the hypothalamus-pituitary-adrenal (HPA) axis pathway is closely related to insulin resistance (IR), glucose, and lipid metabolism disorders in type 2 diabetes mellitus (T2DM). Berberine (BBR) has effect on regulating disorder of glucose and lipid metabolism in T2DM. In fact, activation of the HPA axis pathway is closely related to IR, glucose, and lipid metabolism disorders in T2DM. Here, we investigated whether the therapeutic effect of BBR on T2DM rats is acted through the HPA axis pathway.

METHODS

In this research, we investigated the effects of BBR on the HPA-axis pathway-related indicators and expression of skeletal muscle glucose transporter 4 (GLUT4) in the high-fat diet and streptozotocin-induced T2DM rats, and identify its possible mechanism of improving IR in T2DM.

RESULTS

BBR significantly reduced fasting blood glucose, total cholesterol, and low-density lipoprotein cholesterol in model rats. It also improved the abnormalities of the high-density lipoprotein cholesterol, the insulin resistance index, the insulin sensitivity index, glucagon, and insulin levels. BBR decreased levels of hypothalamic Orexin-A, the OX2R receptor, the corticotropin-releasing hormone, the pituitary and the plasma adrenocorticotropic hormone, as well as serum and urine corticosterone. At the same time, BBR increased mRNA and protein expressions of GLUT4 in skeletal muscles of model rats as well.

CONCLUSION

Those results suggested that BBR can exert inhibition on the HPA-axis and increased skeletal muscle expression of GLUT4 proteins, which may be one of the important mechanisms in BBR to improve IR and regulating glucose and lipid metabolism in T2DM rats.