Cross state-dependent memory retrieval between tramadol and ethanol: involvement of dorsal hippocampal GABAA receptors.

RATIONALE: Tramadol and ethanol, as psychoactive agents, are often abused. Discovering the molecular pathways of drug-induced memory creation may contribute to preventing drug addiction and relapse. OBJECTIVE: The tramadol- and ethanol-induced state-dependent memory (SDM) and cross-SDM retrieval between tramadol and ethanol were examined in this study. Moreover, because of the confirmed involvement of GABAA receptors and GABAergic neurotransmission in memory retrieval impairment, we assessed cross-SDM retrieval between tramadol and ethanol with a specific emphasis on the role of the GABAA receptors. The first hypothesis of this study was the presence of cross-SDM between tramadol and ethanol, and the second hypothesis was related to possible role of GABAA receptors in memory retrieval impairment within the dorsal hippocampus. The cannulae were inserted into the hippocampal CA1 area of NMRI mice, and a step-down inhibitory avoidance test was used to evaluate state dependence and memory recovery. RESULTS: The post-training and/or pre-test administration of tramadol (2.5 and 5 mg/kg, i.p.) and/or ethanol (0.5 and 1 g/kg, i.p.) induced amnesia, which was restored after the administration of the drugs 24 h later during the pre-test period, proposing ethanol and tramadol SDM. The pre-test injection of ethanol (0.25 and 0.5 g/kg, i.p.) with tramadol at an ineffective dose (1.25 mg/kg) enhanced tramadol SDM. Moreover, tramadol injection (1.25 and 2.5 mg/kg) with ethanol at the ineffective dose (0.25 g/kg) promoted ethanol SDM. Furthermore, the pre-test intra-CA1 injection of bicuculline (0.0625, 0.125, and 0.25 µg/mouse), a GABAA receptor antagonist, 5 min before the injection of tramadol (5 mg/kg) or ethanol (1 g/kg) inhibited tramadol- and ethanol-induced SDM dose-dependently. CONCLUSION: The findings strongly confirmed cross-SDM between tramadol and ethanol and the critical role of dorsal hippocampal GABAA receptors in the cross-SDM between tramadol and ethanol.

Therapeutic potential of melatonin in targeting molecular pathways of organ fibrosis.

Fibrosis, the excessive deposition of fibrous connective tissue in an organ in response to injury, is a pathological condition affecting many individuals worldwide. Fibrosis causes the failure of tissue function and is largely irreversible as the disease progresses. Pharmacologic treatment options for organ fibrosis are limited, but studies suggest that antioxidants, particularly melatonin, can aid in preventing and controlling fibrotic damage to the organs. Melatonin, an indole nocturnally released from the pineal gland, is commonly used to regulate circadian and seasonal biological rhythms and is indicated for treating sleep disorders. While it is often effective in treating sleep disorders, melatonin's anti-inflammatory and antioxidant properties also make it a promising molecule for treating other disorders such as organ fibrosis. Melatonin ameliorates the necrotic and apoptotic changes that lead to fibrosis in various organs including the heart, liver, lung, and kidney. Moreover, melatonin reduces the infiltration of inflammatory cells during fibrosis development. This article outlines the protective effects of melatonin against fibrosis, including its safety and potential therapeutic effects. The goal of this article is to provide a summary of data accumulated to date and to encourage further experimentation with melatonin and increase its use as an anti-fibrotic agent in clinical settings.

Dorsal hippocampal CA1 NMDA receptors mediate the interactive effects of quetiapine and lithium on memory retention in male rats.

Objectives: Lithium and quetiapine are administered simultaneously as a treatment for bipolar disorder. The concurrent use of these two drugs has been observed to affect the neurobiological mechanisms underlying learning and memory. To clarify the precise mechanisms involved, we evaluated the possible role of the dorsal hippocampal CA1 NMDA receptors in the interactive effects of lithium and quetiapine in memory consolidation. Materials and Methods: The dorsal hippocampal CA1 regions of adult male Wistar rats were bilaterally cannulated, and a single-trial step-through inhibitory avoidance apparatus was used to assess memory consolidation. Results: Post-training administration of certain doses of lithium (20, 30, and 40 mg/kg, IP) diminished memory consolidation. Post-training administration of higher doses of quetiapine (5, 10, and 20 mg/kg, IP) augmented memory consolidation. Post-training administration of certain doses of quetiapine (2.5, 5, 10, and 20 mg/kg) dose-dependently restored lithium-induced memory impairment. Post-training microinjection of ineffective doses of the NMDA (10-5 and 10-4 µg/rat, intra-CA1) plus an ineffective dose of quetiapine (2.5 mg/kg) restored the lithium-induced memory impairment. Post-training microinjection of ineffective doses of the noncompetitive NMDA receptor antagonist, MK-801 (0.0625 and 0.0125 µg/rat, intra-CA1), diminished the quetiapine-induced (10 mg/kg) memory improvement in lithium-induced memory impairment. Conclusion: These findings suggest a functional interaction between lithium and quetiapine through hippocampal CA1 NMDA receptor mechanisms in memory consolidation.

Prevalence of comorbidities in patients with multiple sclerosis using administrative data from 2007 to 2016 in Iran.

BACKGROUND: Research interest in the impact of comorbidities in MS has been expanding. Based on studies, certain comorbidities are more prevalent in MS population such as depression, anxiety, hypertension and hypercholesterolemia, diabetes, and hypothyroidism. OBJECTIVE: This study aims to describe the prevalence of comorbidities in MS population based on the health insurance claims data. METHOD: This retrospective database analysis was conducted using patient-level medicinal and pharmacy claims data from a leading insurance group (Iranian health insurance) in 2007-2016. MS population was identified based on their Disease Modifying Therapies prescribed by a neurologist (qualified to diagnose MS). Comorbidities in MS and non-MS population were assessed by their prescriptions. Crude and age-standardized prevalence rate (ASPR) of coverage of comorbidities in different age and sex groups and their odds ratio versus non-MS population were assessed. RESULTS: The most common comorbidities were depression (15.50%) and anxiety (10.1%). Hypercholesterolemia, diabetes, hypertension, and hypothyroidism were prevalent in 6%, 3.6%, 3.5%, and 2.7% respectively. Anxiety and depression were more prevalent in middle age group (45-65 years old). But other comorbidities were more prevalent in older age groups. All comorbidities were more prevalent in female except hypertension in patients ≥45 years old. The odds of all comorbidities were higher for male patients with MS rather than their parallel age group in non-MS patients. These also applied for female patients with MS 18-44 years old (except hypertension). CONCLUSION: Using claims data, the prevalence of taking treatment for selected comorbidities in MS population and their association with sex and age, can guide patients, healthcare providers, and policy makers to help improve MS patients' wellbeing.

The prevalence and predictors of herb-drug interactions among Iranian cancer patients during chemotherapy courses.

BACKGROUND: The concurrent usage of herbal medicines with conventional therapies is an important concern in cancer treatment which can lead to unexpected consequences like herb-drug interactions. This study aimed to determine the prevalence of potential herb-drug interactions and to predict factors associated with herb-drug interactions for cancer patients. METHODS: This cross-sectional study was conducted among a convenience sample of 315 cancer patients referring to the oncology clinics of Kerman city in 2018. Data were collected via comprehensive face-to-face interviews and medical chart reviews. A drug interaction checker was used to determine herb-drug interactions. The information of patients was compared based on herb-drug interactions using bivariable logistic regression models, and predictors were determined by the multivariable logistic regression model. All analyses were performed by Stata software version 16. RESULTS: Of 262 patients (83.2% of the patients) who used herbal medicines, 209 patients [79.8% (95% Confidence Intervals (CI): 75.2 - 85.1)] had potential herb-drug interactions. Chamomile was the most popular herbal medicine (n = 163, 78.0%), and minor and moderate herb-drug interactions were caused by green tea (n = 34, 16.3%) and peppermint (n = 78, 37.5%). The number of chemotherapeutic agents (OR: 1.92, 95% CI: 1.43-2.58; P-value < 0.0001) and the experienced of pain during chemotherapy courses (OR = 2.22, 95%CI:1.00-4.94; P-value = 0.04) were some of the predictors of herb-drug interactions among cancer patients. CONCLUSION: Herbal medicine use during chemotherapy was found prevalent among cancer patients; of them, the experience of potential herb-drug interactions was highly frequent. Oncologists and clinical pharmacologists are recommended to take into account challenges associated with herb-drug interactions in their routine practices, particularly during chemotherapy among these patients.

The apelin/APJ signaling system and cytoprotection: Role of its cross-talk with kappa opioid receptor.

Apelin, a regulatory peptide, is an endogenous ligand of the apelin receptor (APJ), which belongs to the G protein-coupled receptor family. The peptide and its receptor are distributed in animal and human tissues, including the cardiovascular and central nervous systems, and studies indicate that apelin signaling could play a role in cytoprotection of cells where it is found. Apelin activity may be modulated by interactions of the APJ receptor with other receptors that result in heteromerization. The interaction of the APJ with other receptor systems increases the signaling repertoire of apelin, thereby allowing it to exert a widened degree of control over cellular physiological functions. This article reviews studies which provide evidence for the physiological importance of APJ/Kappa opioid receptor (KOR) heterodimers in several critical cellular processes, including cell proliferation, and results are discussed that support a role of this peptide and the APJ receptor in functioning of the cardiovascular, gastrointestinal and central nervous systems under normal conditions and pathology, as well as novel signal transduction characteristics resulting following the interaction of APJ and KOR. A better understanding of the cellular protective actions of apelin, and the physiological outcomes from interaction of its receptor with other receptor types could lead to new pharmaceutical targets for various diseases affecting among other organs, the heart, the gastrointestinal system and the brain.

Melatonin effect on platelets and coagulation: Implications for a prophylactic indication in COVID-19.

Severe COVID-19 is associated with the dynamic changes in coagulation parameters. Coagulopathy is considered as a major extra-pulmonary risk factor for severity and mortality of COVID-19; patients with elevated levels of coagulation biomarkers have poorer in-hospital outcomes. Oxidative stress, alterations in the activity of cytochrome P450 enzymes, development of the cytokine storm and inflammation, endothelial dysfunction, angiotensin-converting enzyme 2 (ACE2) enzyme malfunction and renin-angiotensin system (RAS) imbalance are among other mechanisms suggested to be involved in the coagulopathy induced by severe acute respiratory syndrome coronavirus (SARS-CoV-2). The activity and function of coagulation factors are reported to have a circadian component. Melatonin, a multipotential neurohormone secreted by the pineal gland exclusively at night, regulates the cytokine system and the coagulation cascade in infections such as those caused by coronaviruses. Herein, we review the mechanisms and beneficial effects of melatonin against coagulopathy induced by SARS-CoV-2 infection.

Cross state-dependent memory retrieval between cannabinoid CB1 and serotonergic 5-HT1A receptor agonists in the mouse dorsal hippocampus.

Understanding the neurobiological mechanisms of drug-related learning and memory formation may help the treatment of cognitive disorders. Dysfunction of the cannabinoid and serotonergic systems has been demonstrated in learning and memory disorders. The present paper investigates the phenomenon called state-dependent memory (SDM) induced by ACPA (a selective cannabinoid CB1 receptor agonist) and 8-OH-DPAT (a nonselective 5-HT1A receptor agonist) with special focus on the role of the 5-HT1A receptor in the effects of both ACPA and 8-OH-DPAT SDM and cross state-dependent memory retrieval between ACPA and 8-OH-DPAT in a step-down inhibitory avoidance task. The dorsal hippocampal CA1 regions of adult male NMRI mice were bilaterally cannulated, and all drugs were microinjected into the intended injection sites. A single-trial step-down inhibitory avoidance task was used to assess memory retrieval and state-dependence. Post-training and/or pre-test microinjections of ACPA (1 and 2 ng/mouse) and 8-OH-DPAT (0.5 and 1 µg/mouse) dose-dependently induced amnesia. Pre-test administration of the same doses of ACPA and 8-OH-DPAT reversed the post-training ACPA- and 8-OH-DPAT-induced amnesia, respectively. This phenomenon has been named SDM. 8-OH-DPAT (1 µg/mouse) reversed the amnesia induced by ACPA (0.5, 1, and 2 ng/mouse) and induced ACPA SDM. ACPA (2 ng/mouse) reversed the amnesia induced by 8-OH-DPAT (0.25, 0.5, and 1 µg/mouse) and induced 8-OH-DPAT SDM. Pre-test administration of a 5-HT1A receptor antagonist, (S)-WAY 100,135 (0.25 and 0.5 µg/mouse), 5 min before ACPA and 8-OH-DPAT dose-dependently inhibited ACPA- and 8-OH-DPAT-induced SDM, respectively. The present study results demonstrated ACPA- and 8-OH-DPAT- induced SDM. Overall, the data revealed that dorsal hippocampal 5-HT1A receptor mechanisms play a pivotal role in modulating cross state-dependent memory retrieval between ACPA and 8-OH-DPAT.

Hippocampal and prefrontal cortical NMDA receptors mediate the interactive effects of olanzapine and lithium in memory retention in rats: the involvement of CAMKII-CREB signaling pathways.

RATIONALE: Treatment of bipolar disorder (BPD) with lithium and olanzapine concurrent administration is a major medicine issue with the elusive neurobiological mechanisms underlying the cognitive function. OBJECTIVE: To clarify the precise mechanisms involved, the possible role of the hippocampus (HPC) and prefrontal cortical (PFC) NMDA receptors and CAMKII-CREB signaling pathway in the interactive effects of lithium and olanzapine in memory consolidation was evaluated. The dorsal hippocampal CA1 regions of adult male Wistar rats were bilaterally cannulated and a step-through inhibitory avoidance apparatus was used to assess memory consolidation. The changes in p-CAMKII/CAMKII and p-CREB/CREB ratio in the HPC and the PFC were measured by Western blot analysis. RESULTS: Post-training administration of lithium (20, 30, and 40 mg/kg, i.p.) dose-dependently decreased memory consolidation whereas post-training administration olanzapine (2 and 5 mg/kg, i.p.) increased memory consolidation. Post-training administration of certain doses of olanzapine (1, 2, and 5 mg/kg, i.p.) dose-dependently improved lithium-induced memory impairment. Post-training administration of ineffective doses of the NMDA (10-5 and 10-4 µg/rat, intra-CA1) plus an ineffective dose of olanzapine (1 mg/kg, i.p.) dose-dependently improved the lithium-induced memory impairment. Post-training microinjection of ineffective doses of the NMDA (10-5 and 10-4 µg/rat, intra-CA1) dose-dependently potentiated the memory improvement induced by olanzapine (1 mg/kg, i.p.) on lithium-induced memory impairment which was associated with the enhancement of the levels of p-CAMKII and p-CREB in the HPC and the PFC. Post-training microinjection of ineffective doses of the noncompetitive NMDA receptor antagonist, MK-801 (0.0625 and 0.0125 µg/rat, intra-CA1), dose-dependently decreased the memory improvement induced by olanzapine (5 mg/kg, i.p.) on lithium-induced memory impairment which was related to the reduced levels of HPC and PFC CAMKII-CREB. CONCLUSION: The results strongly revealed that there is a functional interaction among lithium and olanzapine through the HPC and the PFC NMDA receptor mechanism in memory consolidation which is mediated with the CAMKII-CREB signaling pathway.

Cross state-dependency of learning between tramadol and MK-801 in the mouse dorsal hippocampus: involvement of nitric oxide (NO) signaling pathway.

RATIONALE: Tramadol, an atypical µ-opioid receptor agonist, as a psychoactive drug, is frequently abused by human beings. Understanding the neurobiological mechanisms of drug-associated learning and memory formation may help prevent drug addiction and relapse. Previous study revealed that dorsal hippocampus (CA1) plays a crucial role in the retrieval of tramadol-associated memory and that its role depends on the expression of CA1 N-methyl-D-aspartate (NMDA) receptors (Jafari-Sabet et al. Can J Physiol Pharmacol 96:45-50, 2018). OBJECTIVE: To clarify the exact mechanisms involved, the activation of CA1 nitric oxide (NO) signaling pathway by L-arginine (a nitric oxide precursor) on the interaction between tramadol and MK-801 in memory retrieval was examined. The dorsal hippocampal CA1 regions of adult male NMRI mice were bilaterally cannulated and a single-trial step-down inhibitory avoidance apparatus was used for the assessment of memory retrieval. RESULTS: Post-training and/or pre-test microinjection of tramadol (0.5 and 1 µg/mouse) and/or a non-competitive NMDA receptor antagonist, MK-801 (0.25 and 0.5 µg/mouse), induced amnesia which were reversed when the same doses of the drugs were administered 24 h later in a pre-test session, suggesting tramadol state-dependent learning (SDL) and MK-801 SDL. The amnesia induced by post-training microinjection of tramadol (1 µg/mouse) was reversed by pre-test microinjection of MK-801 (0.25 and 0.5 µg/mouse). Pre-test microinjection of MK-801 (0.125 and 0.25 µg/mouse) with an ineffective dose of tramadol (0.25 µg/mouse) potentiated tramadol SDL. The amnesia induced by post-training microinjection of MK-801 (0.5 µg/mouse) was reversed by pre-test microinjection of tramadol (0.5 and 1 µg/mouse). Pre-test microinjection of tramadol (0.25 and 0.5 µg/mouse) with an ineffective dose of MK-801 (0.125 µg/mouse) potentiated MK-801 SDL. Pre-test microinjection of ineffective doses of L-arginine (0.125, 025, and 0.5 µg/mouse) improved amnesia induced by the co-administration of tramadol and MK-801. Pre-test microinjection of L-arginine (0.125, 025, and 0.5 µg/mouse) could not reverse amnesia induced by post-training microinjection of tramadol while same doses of L-arginine improved MK-801 response on tramadol SDL. CONCLUSION: The results strongly propose that activation of CA1 NO signaling pathway has a pivotal role in cross SDL among tramadol and MK-801.

A role for Leu118 of loop E in agonist binding to the alpha 7 nicotinic acetylcholine receptor.

Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels mediating fast cholinergic synaptic transmission in the brain and at neuromuscular junctions. We used the structure of the acetylcholine binding protein from Lymnaea stagnalis to model the chicken alpha7 agonist-binding domain. The initial models and a preliminary docking study suggested that position Leu118 may play an important role in determining agonist actions on alpha7. A prediction from these in silico studies, that L118E and L118D would retain binding to acetylcholine but L118K and L118R would not, was confirmed in electrophysiological studies on functional recombinant mutant receptors expressed in Xenopus laevis oocytes. The functional studies also demonstrated that residues at position 118 have a dramatic effect on the actions of imidacloprid (a partial agonist of wild-type alpha7 receptors) and its des-nitro derivative. Molecular dynamics simulations confirmed that Leu118 can strongly influence agonist binding and that the model was robust in terms of its prediction for acetylcholine binding. Together, the results indicate a role for Leu118 in influencing agonist actions on alpha7 nAChRs.

Molecular dynamics studies of AChBP with nicotine and carbamylcholine: the role of water in the binding pocket.

The acetylcholine-binding protein (AChBP) is homologous to the ligand-binding domain of the nicotinic acetylcholine receptor (nAChR) and other members of the Cys-loop family of neurotransmitter receptors. The high-resolution X-ray structures of AChBP mean it has been used as a model from which to understand agonist and antagonist binding to nAChRs. We present here a molecular dynamics (MD) study of AChBP with nicotine and carbamylcholine bound. Our results suggest that the ligand imposes rigidity on the binding pocket residues. The simulations also suggest that the protein undergoes breathing motions with respect to the five-fold axis, a motion that has been postulated to be related to gating in the nAChR. We analyzed the behaviour of the water molecules in and around the binding site and found that they occupied five distinct sites within the binding pocket. Water occupied these sites in the absence of ligand, but the presence of ligand increased the probability that a water molecule would be found in these sites. Finally, we demonstrate how the positions of these waters might be used in the design of new ligands by comparing the positions of these sites with other recent structures.

The alpha7 nicotinic acetylcholine receptor: molecular modelling, electrostatics, and energetics.

The structure of a homopentameric alpha7 nicotinic acetylcholine receptor is modelled by combining structural information from two sources: the X-ray structure of a water soluble acetylcholine binding protein from Lymnea stagnalis, and the electron microscopy derived structure of the transmembrane domain of the Torpedo nicotinic receptor. The alpha7 nicotinic receptor model is generated by simultaneously optimising: (i) chain connectivity, (ii) avoidance of stereochemically unfavourable contacts, and (iii) contact between the beta1-beta2 and M2-M3 loops that have been suggested to be involved in transmission of conformational change between the extracellular and transmembrane domains. A Gaussian network model was used to predict patterns of residue mobility in the alpha7 model. The results of these calculations suggested a flexibility gradient along the transmembrane domain, with the extracellular end of the domain more flexible that the intracellular end. Poisson-Boltzmann (PB) energy calculations and atomistic (molecular dynamics) simulations were used to estimate the free energy profile of a Na+ ion as a function of position along the axis of the pore-lining M2 helix bundle of the transmembrane domain. Both types of calculation suggested a significant energy barrier to exist in the centre of the (closed) pore, consistent with a "hydrophobic gating" model. Estimations of the PB energy profile as a function of ionic strength suggest a role of the extracellular domain in determining the cation selectivity of the alpha7 nicotinic receptor. These studies illustrate how molecular models of members of the nicotinic receptor superfamily of channels may be used to study structure-function relationships.

In silico proteome analysis to facilitate proteomics experiments using mass spectrometry.

Proteomics experiments typically involve protein or peptide separation steps coupled to the identification of many hundreds to thousands of peptides by mass spectrometry. Development of methodology and instrumentation in this field is proceeding rapidly, and effective software is needed to link the different stages of proteomic analysis. We have developed an application, proteogest, written in Perl that generates descriptive and statistical analyses of the biophysical properties of multiple (e.g. thousands) protein sequences submitted by the user, for instance protein sequences inferred from the complete genome sequence of a model organism. The application also carries out in silico proteolytic digestion of the submitted proteomes, or subsets thereof, and the distribution of biophysical properties of the resulting peptides is presented. proteogest is customizable, the user being able to select many options, for instance the cleavage pattern of the digestion treatment or the presence of modifications to specific amino acid residues. We show how proteogest can be used to compare the proteomes and digested proteome products of model organisms, to examine the added complexity generated by modification of residues, and to facilitate the design of proteomics experiments for optimal representation of component proteins.