Fentanyl inhibits glucose-stimulated insulin release from β-cells in rat pancreatic islets

Fentanyl overdose: Temporal effects and prognostic factors in SKH1 mice

Fentanyl exposure and overdose are growing concerns in public health and occupational safety. This study aimed to establish parameters of fentanyl lethality in SKH1 mice for future overdose research. Lethality was determined using the up-down procedure, with subjects monitored post-administration using pulse oximetry (5 min) and then whole-body plethysmography (40 min). Following the determination of subcutaneous dose-response, [18F]Fluorodeoxyglucose positron emission tomography (18 F-FDG PET) was performed after LD10 fentanyl at 40 min, 6 h, 24 h or 7 days post-dose. LD10 and LD50 were observed to be 110 and 135 mg/kg, respectively, and consistent with four-parameter logistic fit values of 111.2 and 134.6 mg/kg (r2  = 0.9996). Overdose (LD10 or greater) yielded three distinct cardiovascular groups: survival, non-survival with blood oxygen saturation (SpO2) minimum ≥37% and non-survival with SpO2 <37%. Breaths per minute, minute volume and inspiratory quotient were significantly different between surviving and non-surviving animals for up to 40 min post-injection. 18 F-FDG PET revealed decreased glucose uptake in the heart, lungs and brain for up to 24 h. These findings provide critical insights into fentanyl lethality in SKH1 mice, including non-invasive respiratory effects and organ-specific impacts that are invaluable for future translational studies investigating the temporal effects of fentanyl overdose.

Interindividual variability in diabetic patients’ response to opium poppy: an overview of impressive factors

Diabetic patients always seek alternative treatments to lower their blood glucose level efficiently, because antidiabetic drugs produce adverse effects and many patients experience reduced response after a treatment period. Opium poppy ( Papaver somniferum) is frequently consumed by diabetic patients for reduction of blood glucose level. Scientific studies found controversial results in the investigation of the blood glucose-lowering effects of opium poppy. In this regard, we explored the antidiabetic effect of opium poppy more closely. The antidiabetic or antihyperglycemic effect of P. somniferum alkaloids were reviewed. Next, opioid receptors and their role in diabetes were explored. In the final part origins of interindividual variabilities in opioid receptors and metabolizing enzymes’ functions including genetic and epigenetic factors were reviewed.

Choice of anesthesia and data analysis method strongly increases sensitivity of 18F-FDG PET imaging during experimental epileptogenesis

Purpose

Alterations in brain glucose metabolism detected by 2-deoxy-2-[¹⁸F]-fluoro-D-glucose (¹⁸F-FDG) positron emission tomography (PET) may serve as an early predictive biomarker and treatment target for epileptogenesis. Here, we aimed to investigate changes in cerebral glucose metabolism before induction of epileptogenesis, during epileptogenesis as well as during chronic epilepsy. As anesthesia is usually unavoidable for preclinical PET imaging and influences the distribution of the radiotracer, four different protocols were compared.

Procedures

We investigated ¹⁸F-FDG uptake phase in conscious rats followed by a static scan as well as dynamic scans under continuous isoflurane, medetomidine-midazolam-fentanyl (MMF), or propofol anesthesia. Furthermore, we applied different analysis approaches: atlas-based regional analysis, statistical parametric mapping, and kinetic analysis.

Results

At baseline and compared to uptake in conscious rats, isoflurane and propofol anesthesia resulted in decreased cortical ¹⁸F-FDG uptake while MMF anesthesia led to a globally decreased tracer uptake. During epileptogenesis, MMF anesthesia was clearly best distinctive for visualization of prominently increased glucometabolism in epilepsy-related brain areas. Kinetic modeling further increased sensitivity, particularly for continuous isoflurane anesthesia. During chronic epilepsy, hypometabolism affecting more or less the whole brain was detectable with all protocols.

Conclusion

This study reveals evaluation of anesthesia protocols for preclinical ¹⁸F-FDG PET imaging as a critical step in the study design. Together with an appropriate data analysis workflow, the chosen anesthesia protocol may uncover otherwise concealed disease-associated regional glucometabolic changes.

The adenosine, adrenergic and opioid pathways in the regulation of insulin secretion, beta cell proliferation and regeneration

Insulin, a key hormone produced by pancreatic beta cells precisely regulates glucose metabolism in vertebrates. In type 1 diabetes, the beta cell mass is destroyed, a process triggered by a combination of environmental and genetic factors. This ultimately results in absolute insulin deficiency and dysregulated glucose metabolism resulting in a number of detrimental pathophysiological effects. The traditional focus of treating type 1 diabetes has been to control blood sugar levels through the administration of exogenous insulin. Newer approaches aim to replace the beta cell mass through pancreatic or islet transplantation. Type 2 diabetes results from a relative insulin deficiency for the prevailing insulin resistance. Treatments are generally aimed at reducing insulin resistance and/or augmenting insulin secretion and the use of insulin itself is often required. It is increasingly being recognized that the beta cell mass is dynamic and increases insulin secretion in response to beta cell mitogens and stress signals to maintain glycemia within a very narrow physiological range. This review critically discusses the role of adrenergic, adenosine and opioid pathways and their interrelationship in insulin secretion, beta cell proliferation and regeneration.

Comparison of Physiological Parameters and Anaesthesia Specific Observations during Isoflurane, Ketamine-Xylazine or Medetomidine-Midazolam-Fentanyl Anaesthesia in Male Guinea Pigs

Guinea pigs (GPs) are difficult to anaesthetize successfully, the choices for anaesthesia are limited and physiological parameters are likely to be influenced substantially under anaesthesia. We implanted blood pressure radio-telemetry devices into 16 male GPs and subjected them to anaesthesia with ketamine-xylazine (KX), medetomidine-midazolam-fentanyl (MMF) or isoflurane (Iso, plus atropine premedication) in a randomized order with a 7 day interval between anaesthesias. Each anaesthesia lasted 40min, after which Iso was discontinued, MMF was fully antagonized with atipamezole-flumazenil-naloxone and KX was partially antagonized with atipamezole. Hemodynamics were recorded continuously for at least 240min after induction and the GPs were monitored for respiratory rate, reflex responses and specific observations until regaining of their righting reflex (RR). Blood for glucose testing was taken from the ear at 7.5, 20 and 40min during anaesthesia. Recovery time was short with MMF and Iso but long for KX. MMF induced only a transient blood pressure drop after antagonization, whereas Iso caused a marked hypotension during maintenance and KX led to moderate hypotension after antagonization. MMF and Iso produced tolerable heart rate changes, but KX led to long term post-anaesthetic bradycardia. Hypothermia occurred with all anaesthesias, but the GPs returned to normothermia the fastest under MMF, followed shortly by Iso. KX, however, caused a profound and prolonged hypothermia. The respiration was depressed with all anaesthesias, substantially with MMF (-41%) and KX (-52%) and severe during Iso maintenance (-71%). Blood glucose with MMF and KX increased throughout the anaesthesia, but the values remained within reference values with all anaesthetics. The reflex responses character and strength varied between the anaesthetics. In conclusion, MMF is the anaesthetic of choice and Iso may be used for short, non-painful procedures. We advise against the use of KX in GPs.

Effects of testosterone replacement on metabolic and inflammatory markers in men with opioid-induced androgen deficiency

OBJECTIVE

Symptomatic androgen deficiency is common in patients taking opioid analgesics, and testosterone replacement in these men improves libido, quality of life and body composition. However, the effects of testosterone replacement on metabolic and inflammatory markers in this setting have not been evaluated. This is important as opiate use itself has been associated with metabolic abnormalities. The objective of this investigation was to determine the effects of testosterone administration on metabolic and inflammatory markers in adult men with opioid-induced androgen deficiency.

METHODS

Sixty-four nondiabetic men aged 18 to 64 years using opioid analgesics for chronic noncancer pain with total testosterone levels <12 nmol/l were randomized to 14 weeks of transdermal testosterone gel or placebo gel daily. Total testosterone levels were measured by liquid chromatography mass spectrometry, and free testosterone was calculated using the law-of-mass-action equation. Metabolic parameters, inflammatory markers and oral glucose tolerance test (OGTT) were evaluated at baseline and 14 weeks.

RESULTS

Baseline characteristics were similar between the two groups. Testosterone concentrations increased from 7·7 ± 3·0 to 27 ± 19 nmol/l in the testosterone group, but did not meaningfully change in placebo group. Mean changes in metabolic and inflammatory markers during intervention did not differ significantly between groups and were not related to changes in on-treatment serum testosterone concentrations. Glucose and insulin response to the 75 g OGTT also did not differ between groups.

CONCLUSION

In this 14-week trial, testosterone administration in men with opioid-induced androgen deficiency was not associated with worsening of metabolic and inflammatory markers.

The effect of time and temperature on viability and performance of Langerhans islets separated from Balb/c mouse after death

Background:

Tissue transplantation plays a pivotal role in the treatment of diseases. Pancreatic beta cell transplantation is the best way to obtain normal blood glucose in patients with diabetes type 1. However, it is not clear how long endocrine pancreas cells can be used for transplantation after the donor's death. The present study was conducted to analyze the performance and viability of pancreatic islet cells after death.

Materials and Methods:

Pancreas was separated from Balb/c mice at different times (0, 1, 4, 6, 12, and 24 h after death) at temperatures of 4°C and 23°C, and was cultured in Roswell_Park_Memorial_Institute (RPMI) 1640. Insulin shock, MTT assay, aldehyde fuchsin staining, dithizone staining, and florescence microscopy methods were applied to analyze the performance of beta cells, cell viability, islets’ diagnosis, islet cells’ diagnosis, and viable and necrotic cells diagnosis, respectively.

Results:

Islets of Langerhans and beta cells were diagnosed. By increasing the temperature and time, the viability and performance of beta cells decreased significantly (P < 0.05).

Conclusion:

The best condition for keeping the islets of Langerhans in terms of viability and performance is 4 h after death at temperature of 4°C.