Assessing the Effects of Opioids on Pathological Memory by a Computational Model

Medication Exposure and Risk of Dementia and Alzheimer's Disease

Alzheimer's disease (AD), a complex neurodegenerative disease (ND), is the most predominant cause of dementia among the elderly. Generally, elderly people have multiple chronic health conditions, like hypertension, arthritis, diabetes, insomnia, bowel problems, and depression. Although prescribed medications have beneficial therapeutic compositions, some may have side effects that could hinder cognitive function or worsen cognitive decline. Hence, we should evaluate those medications to guarantee their safety. In the present mechanistic review, we discussed frequently used categories of medication (analgesics, anticholinergics, benzodiazepines, proton pump inhibitors, and statins), concerning their possible involvement in increasing AD and dementia risks. This review summarized the results of various observational studies, meta-analyses, randomized case-control studies, and systematic reviews. As the results were contradictory, it was difficult to ascertain the clear associations between medication usage and increased risks of dementia or AD. The blood-based biomarkers (BBMs) offer a low-cost and accessible alternative for early diagnosis of AD. Systematic reviews combined with meta-analysis would be crucial tools for accurately assessing and summarizing the efficacy of health interventions, yet randomized clinical trials have always been the best way to help with clinical care decisions. Thus, an open discussion is necessary to help individuals determine whether the advantages of utilizing medications outweigh the possible drawbacks.

Investigating the Cocaine-induced Reduction of Potassium Current on the Generation of Action Potentials Using a Computational Model

Introduction

Drugs of abuse, such as cocaine, affect different brain regions and lead to pathological memories. These abnormal memories may occur due to changes in synaptic transmissions or variations in synaptic properties of neurons. It has been shown that cocaine inhibits delayed rectifying potassium currents in affected brain regions and can create pathological memories.This study investigates how the change in the conductance of delayed rectifying potassium channels can affect the produced action potentials using a computational model.

Methods

We present a computational model with different channels and receptors, including sodium, potassium, calcium, NMDARs, and AMPARs, which can produce burst-type action potentials. In the simulations, by changing the delayed rectifying potassium conductance bifurcation diagram is calculated.

Results

By decreasing the potassium current for a fixed stimulatory signal, burst-type action potentials can be generated. In the following and with a further reduction of potassium conductance, produced action potentials exhibit non-linear and even chaotic behaviors.

Conclusion

Results show that for a specific range of potassium conductance, a chaotic regime emerges in produced action potentials. These chaotic oscillations may play a role in inducing abnormal memories.

Highlights

Cocaine consumption reduces the potassium current in affected cells.Decreasing the potassium currents elicits burst action potentials.Produced bursts might have chaotic behaviors.Chaotic oscillations might be related to the toxic effects of cocaine.

Plain Language Summary

Drugs of abuse such as cocaine can manipulate brain circuits and may form some pathological memories. These memories can lead to long-term addiction. Furthermore, these drugs also can have toxic effects on the cells. Researchers are looking for the mechanisms that can lead to abnormal memories and toxic effects of drugs. It seems that an efficient mechanism that can be used by drugs of abuse is the manipulation of potassium currents in the affected cells. Here, in a computational model, we have shown that changes in the conductance of delayed rectifying potassium channels can lead to nonlinear and even chaotic behaviors in the produced action potentials. These behaviors might have a role in drug toxic effects.

Endogenous opiates and behavior: 2019

This paper is the forty-second consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2019 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 (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).