Mitochondrial impairments contribute to spatial learning and memory dysfunction induced by chronic tramadol administration in rat: Protective effect of physical exercise

Neuroprotective potential of solanesol against tramadol induced zebrafish model of Parkinson's disease: insights from neurobehavioral, molecular, and neurochemical evidence

Parkinson's disease (PD) is a prevalent neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and subsequent depletion of dopamine in the striatum. Solanesol, an alcohol that acts as a precursor to coenzyme Q10, possesses potential applications in managing neurological disorders with antioxidant, anti-inflammatory, and neuromodulatory potential. In this study, a zebrafish model was employed to investigate the effects of solanesol in tramadol induced PD like symptoms. Zebrafish were administered tramadol injections (50 mg/kg) over a 20-day period. Solanesol was administered at doses of 25, 50, and 100 mg/kg, three hours prior to tramadol administration from day 11 to day 20. Behavioral tests assessing motor coordination were conducted on a weekly basis using open field and novel diving tank apparatus. On day 21, the zebrafish were euthanized, and brain tissues were examined for markers of oxidative stress, inflammation, and neurotransmitters level. Chronic tramadol treatment resulted in motor impairment, reduced antioxidant enzyme levels, enhanced release of proinflammatory cytokines in the striatum, and disrupted neurotransmitter balance. However, solanesol administration mitigated these effects and exhibited a neuroprotective effect against neurodegenerative alterations in the zebrafish model of PD. This was evident through improvements in behavior, modulation of biochemical markers, attenuation of neuroinflammation, restoration of neurotransmitters level, and enhancement of mitochondrial activity. The histopathological study also confirmed that solanesol dose dependently restored neuronal cell density which confirmed its neuroprotective potential. Further investigations are required to elucidate the underlying mechanisms of solanesol neuroprotective effects and evaluate its efficacy in human patients.

Effects of moderate intensity training and lithium on spatial learning and memory in a rat model: The role of SIRT3 and PGC1-α expression levels and brain-derived neurotropic factor

In this study we investigated the potential synergistic effects of moderate interval training (MIT) and lithium on spatial learning and memory. Forty-two male Wistar males were classified into six groups including I: Control, II: 10 mg/kg/day IP lithium (Li10), III: MIT, IV: Li10 + MIT, V: 40 mg/kg/day IP lithium (Li40), and VI: Li40 + MIT. Then, the rats underwent Morris Water Maze (MWM) test to assess their spatial memory and learning ability. Brain-derived neurotrophic factor (BDNF) density was measured by enzyme-linked immunosorbent assay (ELISA), and the expression of PGC1 and SIRT3 were assessed via qRT-PCR. The results show that MIT improves both memory and spatial learning; but lithium alone, does not cause this. Additionally, those exposed to a combination of exercise and lithium also had improved spatial learning and memory. Finally, we observed a positive role of BDNF protein, and PGC1 gene on the effects of exercise and lithium.

Maintenance of mitochondrial function by sinapic acid protects against tramadol-induced toxicity in isolated mitochondria obtained from rat brain

It is reported that tramadol can induce neurotoxic effects with the production of DNA damage, mitochondrial dysfunction, and oxidative stress. The current study aimed to evaluate the potential role of mitochondrial impairment in the pathogenesis of tramadol-induced neurotoxicity, and protective effect of sinapic acid (SA) against it in isolated mitochondria from rat brain. Mitochondria were isolated and were incubated with toxic concentrations (100 μM) of tramadol and then cotreated with tramadol + SA (10, 50, and 100 μM). Biomarkers of mitochondrial toxicity including succinate dehydrogenases (SDH) activity, reactive oxygen species (ROS), lipid peroxidation (LPO), mitochondrial membrane potential (MMP), GSH depletion, and mitochondrial swelling were assessed. Our results showed a significant decrease in SDH activity, and a significant increase in ROS, LPO, GSH depletion, MMP collapse, and mitochondrial swelling was detected in tramadol group. We observed that 50 and 100 μM SA cotreatment for 1 h efficiently ameliorated tramadol-caused damage in mitochondrial dysfunction, accumulation of ROS, LPO, GSH depletion, depolarization of mitochondrial membrane potential, and mitochondrial swelling. These data suggest that mitochondrial impairment and oxidative stress are mechanisms involved in the pathogenesis of tramadol-induced neurotoxicity. Also, results indicate that SA antagonizes against tramadol-induced mitochondrial toxicity and suggest SA may be a preventive/therapeutic agent for tramadol-induced neurotoxicity complications.

Di (2-ethylhexyl) phthalate alters neurobehavioral responses and oxidative status, architecture, and GFAP and BDNF signaling in juvenile rat's brain: Protective role of Coenzyme10

Di-(2-ethylhexyl) phthalate (DEHP), a phthalate plasticizer, is widely spread in the environment, presenting hazards to human health and food safety. Hence, this study examined the probable preventive role of coenzyme10 (CQ10) (10 mg/kg.b.wt) against DEHP (500 mg/kg.wt) - induced neurotoxic and neurobehavioral impacts in juvenile (34 ± 1.01g and 3 weeks old) male Sprague Dawley rats in 35-days oral dosing trial. The results indicated that CQ10 significantly protected against DEHP-induced memory impairment, anxiety, depression, spatial learning disorders, and repetitive/stereotypic-like behavior. Besides, the DEHP-induced depletion in dopamine and gamma amino butyric acid levels was significantly restored by CQ10. Moreover, CQ10 significantly protected against the exhaustion of CAT, GPx, SOD, GSH, and GSH/GSSG ratio, as well as the increase in malondialdehyde, Caspas-3, interleukin-6, and tumor necrosis factor-alpha brain content accompanying with DEHP exposure. Furthermore, CQ10 significantly protected the brain from the DEHP-induced neurodegenerative alterations. Also, the increased immunoexpression of brain-derived neurotrophic factor, not glial fibrillary acidic protein, in the cerebral, hippocampal, and cerebellar brain tissues due to DEHP exposure was alleviated with CQ10. This study's findings provide conclusive evidence that CQ10 has the potential to be used as an efficient natural protective agent against the neurobehavioral and neurotoxic consequences of DEHP.

Exercise before pregnancy exerts protective effect on prenatal stress-induced impairment of memory, neurogenesis, and mitochondrial function in offspring

Stress during pregnancy has a negative effect on the fetus. However, maternal exercise has a positive effect on the cognitive function of the fetus and alleviates the negative effects of stress. This study aimed to demonstrate whether exercise before pregnancy has a protective effect on prenatal stress-induced impairment of memory, neurogenesis and mitochondrial function in mice offspring. In this experiment, immunohistochemistry, Western blot, measurement of mitochondria oxygen respiration, and behavior tests were performed. Spatial memory and short-term memory of the offspring from the prenatal stress with exercise were increased compared to the offspring from the prenatal stress. The numbers of doublecortin-positive and 5-bromo-2'-deoxyuridine-positive cells in the hippocampal dentate gyrus of the offspring from the prenatal stress with exercise were higher compared to the offspring from the prenatal stress. The expressions of brain-derived neurotrophic factor, postsynaptic density 95 kDa, and synaptophysin in the hippocampus of the offspring from the prenatal stress with exercise were enhanced compared to the offspring from the prenatal stress. Oxygen consumption of the offspring from the prenatal stress with exercise were higher compared to the offspring from the prenatal stress. Exercise before pregnancy alleviated prenatal stress-induced impairment of memory, neurogenesis, and mitochondrial function. Therefore, exercise before pregnancy may have a protective effect against prenatal stress of the offspring.

Role of apoptosis and autophagy in mediating tramadol-induced neurodegeneration in the rat hippocampus

BACKGROUND

Tramadol (TRA) is an analgesic prescribed for treating mild to moderate pains, the abuse of which has increased in recent years. Chronic tramadol consumption produces neurotoxicity, although the mechanisms are unclear. The present study investigated the involvement of apoptosis and autophagy signaling pathways and the mitochondrial system in TRA-induced neurotoxicity.

MATERIALS AND METHODS

Sixty adult male Wistar rats were divided into five groups that received standard saline or TRA in doses of 25, 50, 75, 100, or 150 mg/kg intraperitoneally for 21 days. On the 22nd day, the Open Field Test (OFT) was conducted. Jun N-Terminal Kinase (JNK), B-cell lymphoma-2 (Bcl-2), Beclin1, and Bcl-2-like protein 4 (Bax) proteins and tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) were measured in rat hippocampal tissue.

RESULTS

TRA at doses 75, 100, and 150 mg/kg caused locomotor dysfunction in rats and increased total and phosphorylated forms of JNK and Beclin-1, Bax, and Caspase-3. TRA at the three higher doses also increased the phosphorylated (inactive) form of Bcl-2 level while decreasing the unphosphorylated (active) form of Bcl-2. Similarly, the protein levels of TNF-α and IL-1β were increased dose-dependently. The mitochondrial respiratory chain enzymes were reduced at the three higher doses of TRA.

CONCLUSION

TRA activated apoptosis and autophagy via modulation of TNF-α or IL-1β/JNK/Bcl-2/Beclin1 and Bcl-2/Bax signaling pathways and dysfunction of mitochondrial respiratory chain enzymes.

Neuroprotective potential of trimetazidine against tramadol-induced neurotoxicity: role of PI3K/Akt/mTOR signaling pathways

Tramadol (TRA) causes neurotoxicity whereas trimetazidine (TMZ) is neuroprotective. The potential involvement of the PI3K/Akt/mTOR signaling pathway in the neuroprotection of TMZ against TRA-induced neurotoxicity was evaluated. Seventy male Wistar rats were divided into groups. Groups 1 and 2 received saline or TRA (50 mg/kg). Groups 3, 4, and 5 received TRA (50 mg/kg) and TMZ (40, 80, or 160 mg/kg) for 14 days. Group 6 received TMZ (160 mg/kg). Hippocampal neurodegenerative, mitochondrial quadruple complex enzymes, phosphatidylinositol-3-kinases (PI3Ks)/protein kinase B levels, oxidative stress, inflammatory, apoptosis, autophagy, and histopathology were evaluated. TMZ decreased anxiety and depressive-like behavior induced by TRA. TMZ in tramadol-treated animals inhibited lipid peroxidation, GSSG, TNF-α, and IL-1β while increasing GSH, SOD, GPx, GR, and mitochondrial quadruple complex enzymes in the hippocampus. TRA inhibited Glial fibrillary acidic protein expression and increased pyruvate dehydrogenase levels. TMZ reduced these changes. TRA decreased the level of JNK and increased Beclin-1 and Bax. TMZ decreased phosphorylated Bcl-2 while increasing the unphosphorylated form in tramadol-treated rats. TMZ activated phosphorylated PI3Ks, Akt, and mTOR proteins. TMZ inhibited tramadol-induced neurotoxicity by modulating the PI3K/Akt/mTOR signaling pathways and its downstream inflammatory, apoptosis, and autophagy-related cascades.

Bee venom (Apis mellifera L.) rescues zinc oxide nanoparticles induced neurobehavioral and neurotoxic impact via controlling neurofilament and GAP-43 in rat brain

This study investigated the possible beneficial role of the bee venom (BV, Apis mellifera L.) against zinc oxide nanoparticles (ZNPs)-induced neurobehavioral and neurotoxic impacts in rats. Fifty male Sprague Dawley rats were alienated into five groups. Three groups were intraperitoneally injected distilled water (C 28D group), ZNPs (100 mg/kg b.wt) (ZNPs group), or ZNPs (100 mg/kg.wt) and BV (1 mg/ kg.bwt) (ZNPs + BV group) for 28 days. One group was intraperitoneally injected with 1 mL of distilled water for 56 days (C 56D group). The last group was intraperitoneally injected with ZNPs for 28 days, then BV for another 28 days at the same earlier doses and duration (ZNPs/BV group). Depression, anxiety, locomotor activity, spatial learning, and memory were evaluated using the forced swimming test, elevated plus maze, open field test, and Morris water maze test, respectively. The brain contents of dopamine, serotonin, total antioxidant capacity (TAC), malondialdehyde (MDA), and Zn were estimated. The histopathological changes and immunoexpressions of neurofilament and GAP-43 protein in the brain tissues were followed. The results displayed that BV significantly decreased the ZNPs-induced depression, anxiety, memory impairment, and spatial learning disorders. Moreover, the ZNPs-induced increment in serotonin and dopamine levels and Zn content was significantly suppressed by BV. Besides, BV significantly restored the depleted TAC but minimized the augmented MDA brain content associated with ZNPs exposure. Likewise, the neurodegenerative changes induced by ZNPs were significantly abolished by BV. Also, the increased neurofilament and GAP-43 immunoexpression due to ZNPs exposure were alleviated with BV. Of note, BV achieved better results in the ZNPs + BV group than in the ZNPs/BV group. Conclusively, these results demonstrated that BV could be employed as a biologically effective therapy to mitigate the neurotoxic and neurobehavioral effects of ZNPs, particularly when used during ZNPs exposure.

The Effect of Physical Exercise Pretreatment on Spatial Memory and Learning and Function of Mitochondria in the Brain in Type 2 Diabetic Rats

Background

The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide, and this issue is one of the major concerns in the pending years. T2DM causes numerous complications, including cognition, learning, and memory impairments. The positive effect of physical exercise as a popular approach has been shown in many chronic diseases. Further, the improvement effects of exercise on cognition and memory impairment have been noticed.

Objectives

This study examines the possible preventative effects of physical exercise on spatial memory attenuation and brain mitochondrial dysfunction caused by T2DM.

Methods

Male Wistar rats received treadmill exercise (30 min per day, five days per week for two or four weeks). Then, T2DM was induced by a high-fat diet and an injection of streptozotocin (30 mg/kg). Spatial learning and memory were assessed by the Morris water maze test. Further, brain mitochondrial function, including reactive oxygen species (ROS) generation, mitochondrial membrane potential (MMP), mitochondrial swelling, outer membrane damage, cytochrome c release, and ADP/ATP ratio, were measured.

Results

Impaired spatial memory in T2DM rats was observed. Furthermore, brain mitochondrial dysfunction was demonstrated proved by increased ROS generation, MMP collapse, mitochondrial swelling, outer membrane damage, cytochrome c release, and ADP/ATP ratio. Conversely, physical exercise, before diabetes onset, significantly ameliorated spatial memory impairment and brain mitochondrial dysfunction.

Conclusions

This study reveals that physical exercise could prevent diabetes-induced spatial memory impairment. Moreover, it could ameliorate brain mitochondrial dysfunction as one of the possible underlying mechanisms of spatial memory impairment in T2DM.

Mitochondrial Dysfunction Involved in the Cytotoxicity of Tramadol in Human Endometrial Carcinoma Cells

Tramadol is a common anesthetic used to treat cancer pain, including endometrial cancer, but its function in endometrial cancer remains unclear. The purpose of this study was to elucidate the antitumor effects of tramadol on human endometrial cancer cells. Colony formation, BrdU, cell cycle profiles, apoptosis, ROS, and Western blot analyses were used to study the response of endometrial cancer cells to tramadol. JC-1 and seahorse metabolic flux assays were used to detect the effect of tramadol on mitochondria in endometrial cancer cells. Combination index was used to detect the interaction of tramadol with chemotherapy drugs in endometrial cancer cells. In this study, we found that tramadol was able to inhibit proliferation and induce cell cycle arrest, ROS generation, and apoptosis in two types of endometrial cancer cells. In addition, tramadol treatment also induced mitochondrial dysfunction in endometrial cancer cells by causing a loss of mitochondrial membrane potential and a decreased oxygen consumption rate. More importantly, the synergetic effect of tramadol with doxorubicin or cisplatin was further confirmed in endometrial cancer cells by the results of the combination index and apoptosis assay. In summary, our findings indicate that tramadol has an antitumor effect on endometrial cancer cells, which might serve as a potential adjuvant therapy strategy for endometrial cancer.

Evaluation of mitochondrial dysfunction due to oxidative stress in therapeutic, toxic and lethal concentrations of tramadol

Tramadol (TR) is a centrally acting analgesic drug that is used to relieve pain. The therapeutic (0.1-0.8 mg/l), toxic (1-2 mg/l) and lethal (>2 mg/l) ranges were reported for TR. The present study was designed to evaluate which doses of TR can induce liver mitochondrial toxicity. Mitochondria were isolated from the five rats' liver and were incubated with therapeutic to lethal concentrations (1.7-600 μM) of TR. Biomarkers of oxidative stress including: reactive oxygen species (ROS), lipid peroxidation (LPO), protein carbonyl content, glutathione (GSH) content, mitochondrial function, mitochondrial membrane potential (MMP) and mitochondrial swelling were assessed. Our results showed that ROS and LPO at 100 μM and protein carbonylation at 600 μM concentrations of TR were significantly increased. GSH was decreased specifically at 600 μM concentration. Mitochondrial function, MMP and mitochondrial swelling decreased in isolated rat liver mitochondria after exposure to 100 and 300 μM, respectively. This study suggested that TR at therapeutic and toxic levels by single exposure could not induce mitochondrial toxicity. But, in lethal concentration (≥100 μM), TR induced oxidative damage and mitochondria dysfunction. This study suggested that ROS overproduction by increasing of TR concentration induced mitochondrial dysfunction and caused mitochondrial damage via Complex II and membrane permeability transition pores disorders, MMP collapse and mitochondria swelling.

Combined molecular, structural and memory data unravel the destructive effect of tramadol on hippocampus

Tramadol is a synthetic analogue of codeine and stimulates neurodegeneration in several parts of the brain that leads to various behavioral impairments. Despite the leading role of hippocampus in learning and memory as well as decreased function of them under influence of tramadol, there are few studies analyzing the effect of tramadol administration on gene expression profiling and structural consequences in hippocampus region. Thus, we sought to determine the effect of tramadol on both PC12 cell line and hippocampal tissue, from gene expression changes to structural alterations. In this respect, we investigated genome-wide mRNA expression using high throughput RNA-seq technology and confirmatory quantitative real-time PCR, accompanied by stereological analysis of hippocampus and behavioral assessment following tramadol exposure. At the cellular level, PC12 cells were exposed to 600μM tramadol for 48 hrs, followed by the assessments of ROS amount and gene expression levels of neurotoxicity associated with neurodegenerative pathways such as apoptosis and autophagy. Moreover, the structural and functional alteration of the hippocampus under chronic exposure to tramadol was also evaluated. In this regard, rats were treated with tramadol at doses of 50 mg/kg for three consecutive weeks. In vitro data revealed that tramadol provoked ROS production and caused the increase in the expression of autophagic and apoptotic genes in PC12 cells. Furthermore, in-vivo results demonstrated that tramadol not only did induce hippocampal atrophy, but it also triggered microgliosis and microglial activation, causing upregulation of apoptotic and inflammatory markers as well as over-activation of neurodegeneration. Tramadol also interrupted spatial learning and memory function along with long-term potentiation (LTP). Taken all together, our data disclosed the neurotoxic effects of tramadol on both in vitro and in-vivo. Moreover, we proposed a potential correlation between disrupted biochemical cascades and memory deficit under tramadol administration.

Co-occurrence of preconception maternal childhood adversity and opioid use during pregnancy: Implications for offspring brain development

Understanding of the effects of in utero opioid exposure on neurodevelopment is a priority given the recent dramatic increase in opioid use among pregnant individuals. However, opioid abuse does not occur in isolation-pregnant individuals abusing opioids often have a significant history of adverse experiences in childhood, among other co-occurring factors. Understanding the specific pathways in which these frequently co-occurring factors may interact and cumulatively influence offspring brain development in utero represents a priority for future research in this area. We highlight maternal history of childhood adversity (CA) as one such co-occurring factor that is more prevalent among individuals using opioids during pregnancy and which is increasingly shown to affect offspring neurodevelopment through mechanisms beginning in utero. Despite the high incidence of CA history in pregnant individuals using opioids, we understand very little about the effects of comorbid prenatal opioid exposure and maternal CA history on fetal brain development. Here, we first provide an overview of current knowledge regarding effects of opioid exposure and maternal CA on offspring neurodevelopment that may occur during gestation. We then outline potential mechanistic pathways through which these factors might have interactive and cumulative influences on offspring neurodevelopment as a foundation for future research in this area.

Effects of chronic tramadol administration on cognitive flexibility in mice

RATIONALE

Tramadol is widely used for pain relief especially in seniors. However, long-term use of tramadol has serious adverse effects, including cognitive impairment. Besides its memory effects, already demonstrated in animals, a recent clinical report suggests that tramadol could also affect executive function in seniors. Several studies have hypothesized that the anti-muscarinic properties of tramadol could be responsible for the deleterious effects of tramadol on cognition.

OBJECTIVES

We aimed at investigating the effects of chronic administration of tramadol on cognitive flexibility in adult male mice, as assessed by a visual discrimination reversal task using a touchscreen device. The effects of tramadol were further compared to those of scopolamine, a reference muscarinic antagonist.

RESULTS

We found that, during the early phase of the reversal task, when cognitive flexibility is most in demand, both tramadol-treated mice (20 mg/kg, s.c., twice a day) and scopolamine-treated mice (0.5 mg/kg, s.c., twice a day) needed more correction trials and showed a higher perseveration index than saline-treated mice. Therefore, tramadol affects cognitive flexibility, and its anticholinergic properties could be at least partly involved in these deficits.

CONCLUSIONS

In view of these deleterious cognitive effects of tramadol, physicians should be cautious when prescribing this analgesic, especially in seniors who are more vulnerable to adverse drug events and in which alternative prescription should be preferred whenever possible.

Mitochondrial dysfunction and oxidative stress are involved in the mechanism of tramadol-induced renal injury

Tramadol (TMDL) is an opioid analgesic widely administered for the management of moderate to severe pain. On the other hand, TMDL is commonly abused in many countries because of its availability and cheap cost. Renal injury is related to high dose or chronic administration of TMDL. No precise mechanism for TMDL-induced renal damage has been identified so far. The current study aimed to evaluate the potential role of oxidative stress and mitochondrial impairment in the pathogenesis of TMDL-induced renal injury. For this purpose, rats were treated with TMDL (40 and 80 ​mg/kg, i.p, 28 consecutive days). A significant increase in serum Cr and BUN was detected in TMDL groups. On the other hand, TMDL (80 ​mg/kg) caused a substantial increase in urine glucose, ALP, protein, and γ-GT levels. Moreover, urine Cr was significantly decreased in TMDL-treated rats (40 and 80 ​mg/kg). Renal histopathological alterations included inflammation, necrosis, and tubular degeneration in the kidney of TMDL-treated animals. Reactive oxygen species (ROS) formation, increased oxidized glutathione (GSSG), lipid peroxidation, and protein carbonylation was increased, whereas total antioxidant capacity and reduced glutathione levels were considerably decreased in TMDL groups. Significant mitochondrial impairment was also detected in the form of mitochondrial depolarization, adenosine-tri-phosphate (ATP) depletion, mitochondrial permeabilization, lipid peroxidation, and decreased mitochondrial dehydrogenase activity in the kidney of TMDL (80 ​mg/kg)-treated animals. These data suggest mitochondrial impairment and oxidative stress as mechanisms involved in the pathogenesis of TMDL-induced renal injury.

Investigation of alpha-lipoic acid effect on memory impairment considering strain-dependent differences in mice

AIMS

Memory impairment is regarded as one of the most challenging neurological disorders. The present study aimed to investigate behavioral and biochemical differences among similar mouse strains following Scopolamine (SCO) exposure as a widespread memory disturbing agent, and a supremely potent antioxidant, alpha-lipoic acid (ALA).

MATERIALS AND METHODS

Three sets of mouse strains (i.e. SW, NMRI, and NIH mice) were subjected to 2 mg/kg intraperitoneal SCO and/or 50 mg/kg ALA 30 min before each Morris Water Maze (MWM) trial for five consecutive days. Upon completion of the trials, the hippocampal region of the animals was dissected for histopathological and biochemical analyses.

KEY FINDINGS

The results exhibited significant impairments caused by SCO in behavioral tests, including probe test, escape latency, and distance traveled in two strains of NMRI and NIH. Nevertheless, at swimming speed, SCO had no meaningful effect on SW and NIH strains. The level of oxidative stress parameters including MDA, ROS, and SOD increased, FRAP and TTM levels related to the hippocampus decreased. There was also a significant increase in hippocampal acetylcholinesterase levels, ADP/ATP ratio, p-NFkB, and Cyt-c. Conversely, ALA administration resulted in a significant improvement in SCO-induced spatial learning and memory impairments only in the SW and NIH mice, which was associated with a significant reduction in hippocampal AChE activity, ADP/ATP ratio, ROS and MDA levels, and SOD activity.

SIGNIFICANCE

In addition of highlighting the efficacious role of ALA in cognitive functions, the findings of this study signified the behavioral dissimilarities among similar animal strains in case of different chemical exposures.

Working memory and hippocampal expression of BDNF, ARC, and P-STAT3 in rats: effects of diet and exercise

OBJECTIVES

Mounting evidence suggests diet and exercise influence learning and memory (LM). We compared a high-fat, high-sucrose Western diet (WD) to a plant-based, amylose/amylopectin blend, lower-fat diet known as the Daniel Fast (DF) in rats with and without regular aerobic exercise on a task of spatial working memory (WM).

METHODS

Rats were randomly assigned to the WD or DF at 6 weeks of age. Exercised rats (WD-E, DF-E) ran on a treadmill 3 times/week for 30 min while the sedentary rats did not (WD-S, DF-S). Rats adhered to these assignments for 12 weeks, inclusive of ab libitum food intake, after which mild food restriction was implemented to encourage responding during WM testing. For nine months, WM performance was assessed once daily, six days per week, after which hippocampal sections were collected for subsequent analysis of brain-derived neurotrophic factor (BDNF), activity-regulated cytoskeletal protein (ARC), and signal transducer and activator of transcription 3 (P-STAT3, Tyr705).

RESULTS

DF-E rats exhibited the best DSA performance. Surprisingly, the WD-S group outperformed the WD-E group, but had significantly lower BDNF and ARC relative to the DF-S group, with a similar trend from the WD-E group. P-STAT3 expression was also significantly elevated in the WD-S group compared to both the DF-S and WD-E groups.

DISCUSSION

These results support previous research demonstrating negative effects of the WD on spatial LM, demonstrate the plant-based DF regimen combined with chronic aerobic exercise produces measurable WM and neuroprotective benefits, and suggest the need to carefully design exercise prescriptions to avoid over-stressing individuals making concurrent dietary changes.

Cognitive decline prevention in offspring of Pb+2 exposed mice by maternal aerobic training and Cur/CaCO3@Cur supplementations: In vitro and in vivo studies

Heavy metals are considered contaminants that hazardously influence the healthy life of humans and animals as they are widely used in industry. Contact of youngsters and women at ages of parturition with lead (Pb⁺²) is a main related concern, which passes through the placental barricade and its better absorption in the intestine leads to flaws in the fetal developfment. However, the metals threaten animal and human life, in particular throughout developmental stages. Products existing in the nature have a major contribution to innovating chemo-preventives. As a naturally available polyphenol and necessary curcuminoid, curcumin (Cur) is a derivative of the herb Curcuma longa (L.) rhizome, which globally recognized as "wonder drug of life"; however, Cur has a limited clinical use as it is poorly dissolved in water. Therefore, to enhance its clinically relevant parameters, curcumin-loaded calcium carbonate (CaCO₃@Cur) was synthesized by one step coprecipitation method as a newly introduced in this research. Initially, its structure was physio chemically characterized using FT-IR, FESEM and DLS equipment and then the cytotoxicity of lead when it was pretreated with Cur/CaCO₃@Cur were assessed by MTT assay. Both Cur and CaCO₃@Cur diminished the toxic effects of Pb⁺² while the most protective effect on the Pb⁺² cytotoxicity was achieved by pre-incubation of cells with CaCO₃@Cur. Besides, the morphological changes of Pb⁺²-treated cells that were pre-incubated with or without Cur/CaCO₃@Cur were observed by normal and florescent microscopes. A non-pharmacologic method that lowers the hazard of brain damage is exercise training that is capable of both improving and alleviating memory. In the current study, the role of regular aerobic training and CaCO₃@Cur was assessed in reducing the risk of brain damage induced by lead nitrate contact. To achieve the mentioned goal, pregnant Balb/C mice were assigned to five groups (six mice/group) at random: negative and positive controls, aerobic training group and Cur and CaCO₃@Cur treated (50 mg/kg/b.wt) trained groups that exposed to Pb⁺² (2 mg/kg) by drinking water during breeding and pregnancy. With the completion of study, offspring were subjected to the behavioral tasks that was tested by step-through ORT, DLB, MWM and YM tests. As a result, having regular aerobic training and CaCO₃@Cur co-administration with lead nitrate could reverse the most defected behavioral indicators; yet, this was not visible for both sexes and it seems that gender can also be a source of different effects in the animal's body. In fact, having regular aerobic training along with CaCO₃@Cur supplementation during pregnancy may be encouraging protecting potential agents towards the toxicity of Pb⁺² that could be recommended in the areas with high pollution of heavy metals.

Repeated Administration of Clinically Relevant Doses of the Prescription Opioids Tramadol and Tapentadol Causes Lung, Cardiac, and Brain Toxicity in Wistar Rats

Tramadol and tapentadol, two structurally related synthetic opioid analgesics, are widely prescribed due to the enhanced therapeutic profiles resulting from the synergistic combination between μ-opioid receptor (MOR) activation and monoamine reuptake inhibition. However, the number of adverse reactions has been growing along with their increasing use and misuse. The potential toxicological mechanisms for these drugs are not completely understood, especially for tapentadol, owing to its shorter market history. Therefore, in the present study, we aimed to comparatively assess the putative lung, cardiac, and brain cortex toxicological damage elicited by the repeated exposure to therapeutic doses of both prescription opioids. To this purpose, male Wistar rats were intraperitoneally injected with single daily doses of 10, 25, and 50 mg/kg tramadol or tapentadol, corresponding to a standard analgesic dose, an intermediate dose, and the maximum recommended daily dose, respectively, for 14 consecutive days. Such treatment was found to lead mainly to lipid peroxidation and inflammation in lung and brain cortex tissues, as shown through augmented thiobarbituric acid reactive substances (TBARS), as well as to increased serum inflammation biomarkers, such as C reactive protein (CRP) and tumor necrosis factor-α (TNF-α). Cardiomyocyte integrity was also shown to be affected, since both opioids incremented serum lactate dehydrogenase (LDH) and α-hydroxybutyrate dehydrogenase (α-HBDH) activities, while tapentadol was associated with increased serum creatine kinase muscle brain (CK-MB) isoform activity. In turn, the analysis of metabolic parameters in brain cortex tissue revealed increased lactate concentration upon exposure to both drugs, as well as augmented LDH and creatine kinase (CK) activities following tapentadol treatment. In addition, pneumo- and cardiotoxicity biomarkers were quantified at the gene level, while neurotoxicity biomarkers were quantified both at the gene and protein levels; changes in their expression correlate with the oxidative stress, inflammatory, metabolic, and histopathological changes that were detected. Hematoxylin and eosin (H & E) staining revealed several histopathological alterations, including alveolar collapse and destruction in lung sections, inflammatory infiltrates, altered cardiomyocytes and loss of striation in heart sections, degenerated neurons, and accumulation of glial and microglial cells in brain cortex sections. In turn, Masson's trichrome staining confirmed fibrous tissue deposition in cardiac tissue. Taken as a whole, these results show that the repeated administration of both prescription opioids extends the dose range for which toxicological injury is observed to lower therapeutic doses. They also reinforce previous assumptions that tramadol and tapentadol are not devoid of toxicological risk even at clinical doses.

Ameliorative Effect of Melatonin Against Reproductive Toxicity of Tramadol in Rats via the Regulation of Oxidative Stress, Mitochondrial Dysfunction, and Apoptosis-related Gene Expression Signaling Pathway

BACKGROUND

The aim of the present study was to investigate the protective properties of melatonin (MT) against oxidative stress, mitochondrial dysfunction, and apoptosis induced by tramadol-reproductive toxicity in male rats.

METHODS

The rats were divided into the 7 groups of control, melatonin (1.5 mg/kg), tramadol (50 mg/kg), and melatonin (1, 1.5 and 2.5 mg/kg) administered 30 minutes before tramadol and vitamin C group (100 mg/kg). All injections were performed intraperitoneally. After administration for 3 consecutive weeks, the animals were killed and testis tissues were used for assessment of oxidative stress markers including lipid peroxidation (LPO), glutathione (GSH) content and protein carbonyl (PrC), and sperm analysis. Mitochondria were isolated from rat's testis using differential centrifugation technique and were studied in terms of mitochondrial viability, mitochondrial membrane potential (MMP), and mitochondrial swelling. The other part of the tissue sample was placed in RNA protector solution for assessment of Bax and Bcl-2 gene expression through real-time polymerase chain reaction (real-time PCR) assay.

FINDINGS

Tramadol caused a significant decline in epidermal sperm count, motility, and morphology, as well as a significant decrease in GSH level and mitochondrial function, and a significant evaluation of LPO, PrC, MMP, and mitochondrial swelling. In addition, tramadol induced a significant decrease in Bcl-2 gene expression, and increase in Bax gene expression. However, pretreatment of rats with MT improved sperm analysis, and testicular antioxidative status, and mitochondrial function. Furthermore, MT pretreatment regulated testicular Bcl-2 and Bax expressions.

CONCLUSION

Considering the protective effects of MT against reproductive toxicity induced by tramadol, this compound can be used as a possible agent for the prevention and treatment of tramadol-induced reproductive toxicity.

Psychiatric drugs impact mitochondrial function in brain and other tissues

Mitochondria have been linked to the etiology of schizophrenia (SZ). However, studies of mitochondria in SZ might be confounded by the effects of pharmacological treatment with antipsychotic drugs (APDs) and other common medications. This review summarizes findings on relevant mitochondria mechanisms underlying SZ, and the potential impact of psychoactive drugs including primarily APDs, but also antidepressants and anxiolytics. The summarized data suggest that APDs impair mitochondria function by decreasing Complex I activity and ATP production and dissipation of the mitochondria membrane potential. At the same time, in the brains of patients with SZ, antipsychotic drug treatment normalizes gene expression modules enriched in mitochondrial genes that are decreased in SZ. This indicates that APDs may have both positive and negative effects on mitochondria. The available evidence suggests three conclusions i) alterations in mitochondria functions in SZ exist prior to APD treatment, ii) mitochondria alterations in SZ can be reversed by APD treatment, and iii) APDs directly cause impairment of mitochondria function. Overall, the mechanisms of action of psychiatric drugs on mitochondria are both direct and indirect; we conclude the effects of APDs on mitochondria may contribute to both their therapeutic and metabolic side effects. These studies support the hypothesis that neuronal mitochondria are an etiological factor in SZ. Moreover, APDs and other drugs must be considered in the evaluation of this pathophysiological role of mitochondria in SZ. Considering these effects, pharmacological actions on mitochondria may be a worthwhile target for further APD development.

Neurobehavioral Consequences Associated with Long Term Tramadol Utilization and Pathological Mechanisms

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Tramadol is a synthetic analog of codeine used to treat pain of moderate to severe intensity and is reported to have neurotoxic potential. At therapeutic dose, tramadol does not cause major side effects in comparison to other opioid analgesics, and is useful for the management of neurological problems like anxiety and depression. Long term utilization of tramadol is associated with various neurological disorders like seizures, serotonin syndrome, Alzheimer’s disease and Parkinson’s disease. Tramadol produces seizures through inhibition of nitric oxide, serotonin reuptake and inhibitory effects on GABA receptors. Extensive tramadol intake alters redox balance through elevating lipid peroxidation and free radical leading to neurotoxicity and produces neurobehavioral deficits. During Alzheimer’s disease progression, low level of intracellular signalling molecules like cGMP, cAMP, PKC and PKA affect both learning and memory. Pharmacologically tramadol produces actions similar to Selective Serotonin Reuptake Inhibitors (SSRIs), increasing the concentration of serotonin, which causes serotonin syndrome. In addition, tramadol also inhibits GABAA receptors in the CNS has been evidenced to interfere with dopamine synthesis and release, responsible for motor symptoms. The reduced level of dopamine may produce bradykinesia and tremors which are chief motor abnormalities in Parkinson’s Disease (PD).

Genotoxicity and repair capability of Mus musculus DNA following the oral exposure to Tramadol

Tramadol is an analgesic and psychoactive drug that acts primarily upon the central nervous system where it alters brain function, resulting in temporary changes in perception, mood, consciousness and behavior. The aim of present study was to analyze the genotoxicity and repair capability of DNA after Tramadol exposure in albino mice (Mus musculus). For this purpose, forty mice were divided equally into four groups as; a control group (without drug) and three treatment groups that were treated with three doses of Tramadol as minimum dose group, Intermediate dose group and maximum dose group, corresponding to 25 mg/kg, 50 mg/kg and 75 mg/kg of body weight respectively. The dose was given orally for 15 days. After 15 days peripheral blood was drawn from half mice of each group and subjected to comet assay. While the remaining half mice were given a recovery period of 15 days and same procedure was used for blood collection and comet assay. Significant difference in various comet parameters was observed among control and exposed groups. Maximum damage was observed at highest concentration 75 mg/kg of Tramadol and minimum damage was observed at dose 25 mg/kg of Tramadol, while results of repaired mice group showed that repair capability of Tramadol was minor and recovery of Tramadol required a lot of time. It can be concluded that Tramadol cause genotoxicity that is dose dependent and has low repair capability.

μ-Opioid receptor in the CA1 involves in tramadol and morphine cross state-dependent memory

In the present study, the effect of tramadol - an opioid painkiller drug with abuse potential- on amnesia and state-dependent memory and its interaction with the opioidergic system was investigated in male Wistar rats. Intra CA-1 administration of tramadol (0.5, 1, and 2 μg/rat) before training, dose-dependently decreased the learning ability in passive avoidance task. Amnesia induced by pre-train tramadol administration was significantly reversed by pre-test administration of tramadol (1 μg/rat). Pre-test administration of naltrexone (a μ-opioid receptor (MOR) antagonist) inhibited the effect of tramadol on memory retrieval. In addition, the pre-test administration of morphine (1 μg/rat, intra-CA1) also reversed memory impairment induced by pre-train tramadol administration. Although, pre-train morphine administration (1 μg/rat, intra-CA1), induced memory impairment reversed by pre-test tramadol administration (1 μg/rat, intra-CA1). In addition, the level of MOR in the hippocampus decreased in animals with memory impairment due to using tramadol in the training day. However, state-dependent retrieval using tramadol or cross state-dependent retrieval using morphine enhanced the MOR level in the hippocampus. The results of the study suggested that intra-CA1 tramadol administration induced memory impairment, improved by pre-test administration of either tramadol or morphine (MOR agonist). It could be concluded that tramadol is capable to induced state-dependent memory and also, it has a cross state-dependent memory with morphine in the hippocampus, done possibly through MOR.

The effects of tramadol administration on hippocampal cell apoptosis, learning and memory in adult rats and neuroprotective effects of crocin

Tramadol, a frequently used pain reliever drug, present neurotoxic effects associated to cognitive dysfunction. Moreover, crocin has been reported to have neuroprotective effects. The aim of this study was to assess crocin's capacity to protect learning, and memory abilities on tramadol-treated rats. A total of 35 rats were divided into five groups: Control, Saline, tramadol (50 mg/kg), tramadol + crocin(30 mg/kg), crocin groups and treated orally for 28 consecutive days. Morris water maze (MWM) and passive avoidance (PA) tests were done, followed by dissection of the rat's brains for toluidine blue and TUNEL staining. In MWM test, tramadol group spent lower time and traveled shorter distance in the target quadrant (Q1) (P < 0.05). On the other side, the traveled distance in tramadol-crocin group was higher than tramadol (P < 0.05). In PA test, both the delay for entering the dark, and the total time spent in the light compartment decreased in tramadol comparing to the control group (P < 0.05), while it increased in tramadol-crocin compared with the tramadol group (P < 0.05). In tramadol-treated animals, the dark neurons (DNs) and apoptotic cells in CA1, CA3 and DG increased (P < 0.05), while concurrent intake of crocin decreased the number of DNs and apoptotic cells in these areas (P < 0.05). Crocin was able to improve learning and memory of tramadol-treated rats and also decreased DNs and apoptotic cells in the hippocampus. Considering these results, the potential capacity of crocin for decreasing side effects of tramadol on the nervous system is suggested.

A cAMP analog attenuates beta-amyloid (1-42)-induced mitochondrial dysfunction and spatial learning and memory deficits

Alzheimer's disease (AD), a neurodegenerative disorder in elderly, is indicated with deposition of Amyloid β (Aβ) in the brain and accompanied with cognitive impairment. Bucladesine, a phosphodiesterase inhibitor, may ameliorate AD's cognitive dysfunctions through mimicking the action of cAMP and raising its intracellular level. Here, we investigated the effects of bucladesine on Aβ-induced memory and learning impairment in a Morris water maze (MWM) model. Rats were injected with bucladesine (1 μl/side from a 100 μM stock solution) and Aβ (1 μl/side from a 100 μM stock solution) intra-hippocampally and after 19 days were trained for 4 successive days. The oxidative stress was evaluated through measurement of thiobarbituric acid (TBARS), thiol groups, and ferric reducing antioxidant power (FRAP). Effect of Aβ and its combination with bucladesine on the mitochondrial function was assessed according to changes in the ROS generation, mitochondrial membrane potential (MMP), mitochondrial swelling, ATP/ADP ratio, mitochondrial outer membrane damage and cytochrome C release. Our results showed a significant elevation in TBARS level after administration of Aβ causing mitochondrial ROS generation, swelling, outer membrane damage, cytochrome C release and also lower thiol, FRAP, and MMP levels. Aβ-induced spatial memory impairment was prevented by pre-treatment with bucladesine and the changed mitochondrial and biochemical indices upon treatment dose were improved. Taken together, we have obtained satisfactory results suggesting protecting effects of bucladesine against the Aβ-mediated memory deficit and implying its plausible beneficial capacity as a therapeutic agent in oxidative stress-associated neurodegenerative diseases.