Proconvulsant effects of tramadol and morphine on pentylenetetrazol-induced seizures in adult rats using different routes of administration

Association Between Opioid Use Disorder and Seizure Incidents Among Alcohol Use Disorder Patients

Many previous studies have discussed an association between alcohol use disorder (AUD) and seizure incidents. There are also case reports of seizures during opioid withdrawals. Therefore, it is possible that AUD patients may have a higher risk of seizures if they also have opioid use disorder (OUD). However, it remains unproven whether AUD patients with a dual diagnosis of OUD have higher seizure incidents, to our knowledge. This study explored seizure incidents among the patients with a dual diagnosis of AUD and OUD as well as seizures among AUD only or OUD only patients. This study utilized de-identified data from 30 777 928 hospital inpatient encounters at 948 healthcare systems over 4 years (9/1/2018-8/31/2022) from the Vizient^® Clinical Database for this study. Applying the International Classification of Diseases 10th Revision (ICD-10) diagnostic codes, AUD (1 953 575), OUD (768 982), and seizure (1 209 471) encounters were retrieved from the database to examine the effects of OUD on seizure incidence among AUD patients. This study also stratified patient encounters for demographic factors such as gender, age, and race, as well as the Vizient-categorized primary payer. Greatest gender differences were identified among AUD followed by OUD, and seizure patient groups. The mean age for seizure incidents was 57.6 years, while that of AUD was 54.7 years, and OUD 48.9 years. The greatest proportion of patients in all 3 groups were White, followed by Black, with Medicare being the most common primary payer in all 3 categories. Seizure incidents were statistically more common (P < .001, chi-square) in patients with a dual diagnosis of AUD and OUD (8.07%) compared to those with AUD only (7.55%). The patients with the dual diagnosis had a higher odd ratio than those with AUD only or OUD only. These findings across more than 900 health systems provide a greater understanding of seizure risks. Consequently, this information may help in triaging AUD and OUD patients in certain higher-risk demographic groups.

Investigation of the Mechanisms of Tramadol-Induced Seizures in Overdose in the Rat

Tramadol overdose is frequently associated with the onset of seizures, usually considered as serotonin syndrome manifestations. Recently, the serotoninergic mechanism of tramadol-attributed seizures has been questioned. This study’s aim was to identify the mechanisms involved in tramadol-induced seizures in overdose in rats. The investigations included (1) the effects of specific pretreatments on tramadol-induced seizure onset and brain monoamine concentrations, (2) the interaction between tramadol and γ-aminobutyric acid (GABA)A receptors in vivo in the brain using positron emission tomography (PET) imaging and 11C-flumazenil. Diazepam abolished tramadol-induced seizures, in contrast to naloxone, cyproheptadine and fexofenadine pretreatments. Despite seizure abolishment, diazepam significantly enhanced tramadol-induced increase in the brain serotonin (p < 0.01), histamine (p < 0.01), dopamine (p < 0.05) and norepinephrine (p < 0.05). No displacement of 11C-flumazenil brain kinetics was observed following tramadol administration in contrast to diazepam, suggesting that the observed interaction was not related to a competitive mechanism between tramadol and flumazenil at the benzodiazepine-binding site. Our findings do not support the involvement of serotoninergic, histaminergic, dopaminergic, norepinephrine or opioidergic pathways in tramadol-induced seizures in overdose, but they strongly suggest a tramadol-induced allosteric change of the benzodiazepine-binding site of GABAA receptors. Management of tramadol-poisoned patients should take into account that tramadol-induced seizures are mainly related to a GABAergic pathway.

Stimulatory and inhibitory effects of morphine on pentylenetetrazol-induced epileptic activity in rat

AIMS

The present study attempts to evaluate the effects of different doses of morphine on experimental epileptiform activity caused by pentylenetetrazol (PTZ) in rats.

METHODS

Thirty adult male rats were assigned to saline (n = 5), morphine (2, 5, and 10 mg/kg, n = 15), naloxone (1 mg/kg, n = 5), and pre-treated with naloxone+morphine (1 + 10 mg/kg, n = 5) groups. The animals were anesthetized with ketamine + xylazine (80 + 8 mg/kg), and then a bipolar electrode was implanted into the CA1 (AP: -2.76 mm, ML: -1.4 mm and DV: 3 mm). To evaluate the effects of drugs on spike count and their amplitudes by elab amplifier, after drug administration for 25 min, PTZ (80 mg/kg, i.p.) was injected to induce epileptiform activity. Finally, diazepam (10 mg/kg) was used to suppress epileptic activity.

RESULTS

The results revealed that morphine at a dose of 2 mg/kg decreased, and at doses of 5 and 10 mg/kg had an increasing effect on seizure-like events (SLEs). Nevertheless, morphine at a dose of 10 mg/kg enhanced SLEs significantly (p < 0.01). Naloxone at a dose of 1 mg/kg had no significant effect on the spike count but increased amplitude of them (p < 0.001). Moreover, being pretreatment with naloxone at a dose of 1 mg/kg, the morphine group showed significantly increased in the spike count (p < 0.05).

CONCLUSIONS

Morphine has biphasic effects on PTZ-induced epileptiform activities that way at a low dose has an inhibitory effect, but if the dose is increased, it will intensify the desired event and that the stimulatory effects of morphine appear not to be via opioid receptors.

Proconvulsant effects of Nepeta menthoides hydro alcoholic extract in different seizure tests: behavioral and biochemical studies

In Iran, both Nepeta menthoides - the endemic species of Nepeta genus - and Lavandula officinalis are known as Ustukhuddoos and used widely as medicinal herbs. In Iranian traditional medicine, Ustukhuddoos has been recommended for several neuronal diseases including depression and epilepsy. While the antiepileptic effects of Lavandula officinalis have been investigated in a number of studies, no reports are available taking into account the effect of Nepeta menthoides on epilepsy. Since convulsion is an important side effect of some medicinal plants, a thorough study of the effects of Nepeta menthoides on epilepsy seems necessary.

This study was designed to investigate the potential anti- or pro-convulsant activity of Nepeta menthoides and its effects on oxidative stress markers. Since an herbal medicine showed opposite effects in two animal models of epilepsy in our laboratory, authers decided to study Nepeta effects through several seizure tests including the intravenous pentylenetetrazol (i.v. PTZ) infusion, the maximal electroshock (MES), acute PTZ and PTZ-kindling tests. These seizure models are generally used for screening pro- or anti-epileptic drugs. Nepeta menthoides (400 mg/kg) significantly reduced the dose of PTZ necessary for clonus seizure induction. Combining either phenytoin (Phen) or Valproate (Val) with Nepeta decreased their antiepileptic effects. Therefore, Nepeta menthoides not only failed to prevent the seizures but also increased sensitivity to them. Nepeta raised brain NO levels in different seizure tests. It seems there is a relation between NO elevation by Nepeta and increased sensitivity to seizures that should be investigated later.

Neurobehavioral Consequences Associated with Long Term Tramadol Utilization and Pathological Mechanisms

:

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).

Stress during pregnancy affected neonatal outcomes and changed cortisol and leptin levels both in mothers and newborns

BACKGROUND

The present study aimed to determine the effect of perceived stress during pregnancy on neonatal outcomes and cortisol and leptin levels in mothers and their newborns.

METHODS

This longitudinal study was carried out on 110 pregnant women in Miandoab city, Iran. Mothers, who had singleton pregnancies and gestational age of 24 to 28 weeks, were included in the study. The participants were asked to fill out Cohen's Perceived Stress Scale (PSS). The mothers were then tracked in gestational ages of 28-32 weeks, 32-36 weeks, and the time of delivery. The maternal and umbilical cord blood samples were obtained during labor in order to measure leptin and cortisol levels.

RESULTS

Umbilical cortisol level was significantly higher in newborns who had meconium stained amniotic fluid than those who did not. Maternal blood leptin levels at delivery were significantly higher in the mothers whose neonates had respiratory distress, low birth weight, low head circumference, low Apgar score, and were premature than those whose neonates did not have such problems. The level of leptin in umbilical cord blood was significantly higher in neonates who had respiratory distress than those who did not. The results also showed a significant correlation between maternal cortisol levels and PSS during weeks 24-28 and the entire pregnancy. A significant relationship was observed between umbilical leptin and maternal leptin levels.

CONCLUSIONS

It can be concluded that stress during pregnancy is accompanied by fetal distress. The probable reason for newborns distress may be related to increased maternal leptin levels.

Modulatory effect of opioid ligands on status epilepticus and the role of nitric oxide pathway

Epilepsy is a chronic disorder that causes unprovoked, recurrent seizures. Status epilepticus (SE) is a medical emergency associated with significant morbidity and mortality. Morphine has been the cornerstone of pain controlling medicines for a long time. In addition to the analgesic and opioid responses, morphine has also revealed anticonvulsant effects in different epilepsy models including pentylenetetrazole (PTZ)-induced seizures threshold. Some authors suggest that nitric oxide (NO) pathway interactions of morphine explain the reason for its pro or anticonvulsant activities. To induce SE, injection of a single dose of lithium chloride (127 mg/kg, intraperitoneal (i.p.)) 20 h before pilocarpine (60 mg/kg, i.p.) was used. Administration of morphine (15 mg/kg, i.p.) inhibited the SE and decreased the mortality in rats when injected 30 min before pilocarpine. On the other hand, injection of L-N^G-nitro arginine methyl ester (L-NAME, a nonselective NO synthase (NOS) blocker; 10 mg/kg, i.p.), 7-nitroindazole (7-NI, a neuronal NOS (nNOS) blocker; 30 mg/kg, i.p.), and aminoguanidine (AG, an inducible NOS (iNOS) blocker; 50 mg/kg, i.p.) 15 min before morphine, significantly reversed inhibitory effect of morphine on SE. Subsequently, measurement of nitrite metabolite levels in the hippocampus of SE-induced rats displayed high levels of nitrite metabolite for the control group. However, after injection of morphine in SE-induced rats, nitrite metabolite levels reduced. In conclusion, these findings demonstrated that NO pathway (both nNOS and iNOS) interactions are involved in the anticonvulsant effects of morphine on the SE signs and mortality rate induced by lithium-pilocarpine in rats.

Prenatal stress and elevated seizure susceptibility: Molecular inheritable changes

Stressful episodes are common during early-life and may have a wide range of negative effects on both physical and mental status of the offspring. In addition to various neurobehavioral complications induced by prenatal stress (PS), seizure is a common complication with no fully explained cause. In this study, the association between PS and seizure susceptibility was reviewed focusing on sex differences and various underlying mechanisms. The role of drugs in the initiation of seizure and the effects of PS on the nervous system that prone the brain for seizure, especially the hypothalamic-pituitary-adrenal (HPA) axis, are also discussed in detail by reviewing the papers studying the effect of PS on glutamatergic, gamma-aminobutyric acid (GABA)ergic, and adrenergic systems in the context of seizure and epilepsy. Finally, epigenetic changes in epilepsy are described, and the underlying mechanisms of this change are expanded. As the effects of PS may be life-lasting, it is possible to prevent future psychiatric and behavioral disorders including epilepsy by preventing avoidable PS risk factors.

Acute and chronic effects of morphine on Low-Mg2+ ACSF-induced epileptiform activity during infancy in mice hippocampal slices

Interaction of morphine and seizure is complex. Mouse brain hippocampal slices were used to estimate how acute and chronic morphine treatment alters the low-magnesium artificial cerebrospinal fluid (LM-ACSF)-induced seizure activity. Hippocampal slices were taken from the normal and morphine-treated mice. The normal mice received saline while the other group (morphine-treated mice) received morphine daily for 5 consecutive days. Saline/morphine administration was performed subcutaneously (s.c, 0.1 mL) at postnatal days 14-18. Hippocampal slices of all animals were perfused with LM-ACSF followed by different morphine concentrations (0, 10, 100, and 1000 μM) or naloxone (10 μM). Changes in the spike count were considered as indices for quantifying the seizure activity in the slices. In hippocampus of both groups perfused with 10 or 1000 μM morphine, epileptiform activity was suppressed while it was potentiated at 100 μM morphine. The excitatory effect of morphine at 100 μM was stronger in normal mice (acute exposure) than in dependent mice (chronic exposure). Naloxone suppressed the epileptiform activities in both groups. Suppressive effect of naloxone was more significant in morphine-treated mice than in normal mice. The seizure activity in morphine-dependent mice was more labile than that of normal mice. It can be concluded that morphine had a biphasic effect on LM-ACSF-induced epileptiform activities in both groups. The occurrence of seizure was comparable in acute and chronic exposure of morphine but strength of the effect was considerably robust in normal mice. The down regulation of opioid receptors in chronic exposure is likely to be responsible for these differences.

Effect of early-life inflammation and magnesium sulfate on hyperthermia-induced seizures in infant rats: Susceptibility to pentylenetetrazol-induced seizures later in life

This study investigated the effect of inflammation and MgSO₄ pretreatment on behaviors caused by hyperthermia (HT) and the effect of these interventions on PTZ-induced seizure a week later. In this experimental study, rat pups experienced inflammation on postnatal day 10 (P10). On P18-19, the pups received either saline or MgSO₄ then subjected to hyperthermia. On P25-26, PTZ-induced seizure was initiated in the rats. Neonatal inflammation increased the susceptibility to HT-induced seizure. Inflammation and HT increased the susceptibility to PTZ-induced seizure. Pretreatment with MgSO₄ before hyperthermia decreased the susceptibility to both HT- and PTZ-induced seizure. Furthermore, calcium and magnesium blood levels significantly decreased compared to control rats. It can be concluded that neonatal inflammation potentiates while pretreatment with MgSO₄ attenuates HT-induced seizures. Also, neonatal inflammation and HT potentiate PTZ-induced seizure initiated one week later.

Evaluation of the role of different neurotransmission systems in the anticonvulsant action of sildenafil in the 6 Hz-induced psychomotor seizure threshold test in mice

Sildenafil influences seizure activity in animal seizure models, and its both proconvulsant and anticonvulsant effects were reported. We previously found that this PDE5 inhibitor significantly increased seizure threshold for the 6 Hz-induced psychomotor seizures in mice and therefore we aimed to investigate the influence of some modulators of neurotransmitter receptors, i.e., diazepam (GABA/benzodiazepine receptor agonist), flumazenil (GABA/benzodiazepine receptor antagonist), N-methyl-d-aspartic acid (NMDA glutamate receptor agonist), CGP 37849 (NMDA receptor antagonist), metergoline (serotonin receptor antagonist), 8-cyclopentyl-1,3-dipropylxanthine (adenosine A₁ receptor antagonist) and β-funaltrexamine (μ opioid receptor antagonist), on the anticonvulsant effect of sildenafil in this test. Additionally, we estimated influence of the studied compounds and their combinations with sildenafil on the muscular strength (assessed in the grip strength test) and motor coordination (assessed in the chimney test) in mice. Our results indicate that anticonvulsant properties of sildenafil in the 6 Hz test in mice might be related to its interactions with the GABAergic, glutamatergic, serotonergic and adenosinergic neurotransmission. We did not find interactions between sildenafil and μ opioid receptors. Neither the studied ligands nor their combinations with sildenafil impaired muscular strength and motor coordination. In conclusion, sildenafil has complex and extensive influence on neurotransmission and seizure generation in the CNS.

Effect of prenatal stress on ɑ5 GABAA receptor subunit gene expression in hippocampus and pilocarpine induced seizure in rats

The GABAergic synapses go through structural and functional maturation during early brain development. Maternal stress alters GABAergic synapses in developing brain, which are associated with the pathophysiology of neuropsychiatric disorders in adults. The present study aimed to investigate the effect of prenatal restraint stress (PS) on pilocarpine-induced seizure and ɑ5 subunit of γ-amino butyric acid type A (GABA_A) receptor expression in hippocampus. Pregnant Wistar rats were subjected to PS at gestational days 15-17 and the pups were examined for susceptibility to seizure and ɑ5 subunit of GABA_A receptor expression in hippocampus at postnatal days 14 and 21 (P14 and PND 21). Quantitative real-time PCR was used for evaluating the gene expression in the pups. Pilocarpine was injected intraperitoneally into the pups and seizure behaviors were recorded. The results showed that ɑ5 subunit mRNA expression significantly increased in hippocampus at both the P14 and P21 in the stressed rats. However, ɑ5 subunit level was greater at the P21 than at the P14 in both the groups. Latency of first tonic-clonic seizure significantly decreased in the PS group compared to the control pups. Number and duration of tonic-clonic seizures increased in the PS rats compared to the controls. PS led to an increase in total score of seizure at the P14 and P21. It can be concluded that PS increases the seizure susceptibility and GABA_A receptor ɑ5 subunit gene expression in offspring; it is likely that the mechanism of increased seizure susceptibility by PS, at least in part, can increase the GABA_A receptor ɑ5 subunit gene expression in hippocampus.

Intracerebroventricular administration of cigarette smoke condensate induced generalized seizures reduced by muscarinic receptor antagonist in rats

Tobacco smoking is considered the greatest risk factor for early death caused by noncommunicable diseases. Currently, there are more than one billion tobacco smokers in the world predisposed to many diseases including heart attack, stroke, cancer, and premature birth or birth defects related to the consumption of cigarettes. However, studies on the association between tobacco smoking and seizures or epilepsy are insufficient and not well documented. In the present study, the authors examined the convulsive effects of the intracerebroventricular administration of cigarette smoke condensate (CSC, 2μl/Rat) in rats and compared it with the intensity of seizures in the kainic acid (KA)-induced seizure model of epilepsy. The role of the cholinergic system was also investigated by testing the effect of the muscarinic acetylcholine receptors (mAChRs) antagonist atropine (2ml/kg) on CSC-induced seizures. The results indicate that a central injection of CSC produces an epileptic behavior similar to that induced by KA, the similarities include the following parameters: time latency of seizures, latency and duration of tonic-clonic seizures, duration of seizures, survival, and tonic-clonic rate. However, a pretreatment with atropine reduced seizures and all their parameters.

Pregestational stress attenuated fertility rate in dams and increased seizure susceptibility in offspring

Many studies have found that stress during pregnancy is linked to an increased incidence of epileptic behaviors and reproductive disorders. However, few works have investigated the effect of pregestational stress on seizure susceptibility in the offspring. We investigated the effect of pregestational stress on epileptic behaviors in the offspring as well as fertility rate in dams. The male and female rats were randomly divided into four groups to form a combination of control and stressed groups for each sex. The rats were subjected to predatory stress (exposed to a cat) twice per day for 50 (male) and 15 (female) consecutive days. At the end of the stress procedure, the rats were coupled as follows: both male and female control (M_C-F_C), male stressed/female control (M_S-F_C), male control/female stressed (M_C-F_S), and both male and female stressed (M_S-F_S). Then, the puppies born from these groups were counted and evaluated for pentylentetrazole (PTZ)-induced seizure. There was no significant difference between the male and female pups in each identical group in terms of litter size and epileptic behaviors, except duration of tail rigidity and duration of immobility. The total score of seizure increased in all the stressed groups, but more severely in the M_S-F_S group. However, the onset of the first epileptic behavior and tonic-clonic seizure significantly decreased in the stressed groups. Moreover, fertility rate significantly decreased in the stressed groups compared with the control group, but there was no significant difference in terms of litter size between the groups. These data revealed the impact of pregestational stress during spermatogenesis and oogenesis on fertility rate in dams and epileptic behaviors in the offspring.

Association of Serum Prolactin Concentrations with Renal Failure in Diabetic Patients

Background and aims: Diabetes is one of the causes of end-stage renal disease, so that about 70% of all diabetic patients have nephropathy. Prolactin is a hormone that is affected by diabetes but the interaction between diabetes and prolactin has not been understood properly. This study aimed to evaluate the relationship between changes in serum prolactin levels in diabetic patients with renal failure.

Material and methods: In this study 223 individuals were participated and after assessment of inclusion/exclusion criteria 189 individuals were evaluated. Finally, the individuals were divided into three groups: Control (C), Diabetic (D), and Diabetic Nephropathy (DN). Blood samples were collected between 8.00 a.m. and 12.00 a.m. for measurement of prolactin levels and biochemical analysis.

Results: The results showed that sodium, potassium, urea, creatinine and prolactin significantly increased in DN group compared to control individuals (P< 0.001). The prolactin levels were significantly decreased in the group of patients with diabetes (P< 0.001).

Conclusion: The results of the current study indicated that serum prolactin level decreased in diabetes while it increased in diabetic nephropathy.

Prenatal stress potentiates febrile seizure and leads to long-lasting increase in cortisol blood levels in children under 2years old

Neurological disorders can be exacerbated in an offspring that is exposed to stress prenatally. This study is aimed to investigate the severity of febrile seizures (FS) in the offspring under 2years old that were prenatally stressed. In this study, 158 children below 2years old with FS were selected. Information about convulsion including seizure lasting, recurrence of seizure, age of the first seizure and type of FS was gathered. Blood samples were obtained from the offspring to measure the cortisol blood levels. Questionnaire was filled in to evaluate the perceived stress and exposure or non-exposure to major stresses during pregnancy. Results of this study showed that both high Perceived Stress Scores (PSS) during pregnancy and exposure to major stresses during pregnancy significantly increased seizure duration and seizure intensity. Also, the appearance of complex FS was significantly higher in prenatally stressed children than the unexposed ones. Further, cortisol blood levels were significantly higher in prenatally stressed subjects. It can be concluded that both higher PSS and/or exposure to major stresses during pregnancy potentiate FS parameters and lead to long lasting increase in cortisol blood levels in the offspring.

Endogenous Opiates and Behavior: 2015

This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia, stress and social status, tolerance and dependence, learning and memory, eating and drinking, drug abuse and alcohol, sexual activity and hormones, pregnancy, development and endocrinology, mental illness and mood, seizures and neurologic disorders, electrical-related activity and neurophysiology, general activity and locomotion, gastrointestinal, renal and hepatic functions, cardiovascular responses, respiration and thermoregulation, and immunological responses.

Mechanisms of tramadol-related neurotoxicity in the rat: Does diazepam/tramadol combination play a worsening role in overdose?

Poisoning with opioid analgesics including tramadol represents a challenge. Tramadol may induce respiratory depression, seizures and serotonin syndrome, possibly worsened when in combination to benzodiazepines. Our objectives were to investigate tramadol-related neurotoxicity, consequences of diazepam/tramadol combination, and mechanisms of drug-drug interactions in rats. Median lethal-doses were determined using Dixon-Bruce's up-and-down method. Sedation, seizures, electroencephalography and plethysmography parameters were studied. Concentrations of tramadol and its metabolites were measured using liquid-chromatography-high-resolution-mass-spectrometry. Plasma, platelet and brain monoamines were measured using liquid-chromatography coupled to fluorimetry. Median lethal-doses of tramadol and diazepam/tramadol combination did not significantly differ, although time-to-death was longer with combination (P=0.04). Tramadol induced dose-dependent sedation (P<0.05), early-onset seizures (P<0.001) and increase in inspiratory (P<0.01) and expiratory times (P<0.05). The diazepam/tramadol combination abolished seizures but significantly enhanced sedation (P<0.01) and respiratory depression (P<0.05) by reducing tidal volume (P<0.05) in addition to tramadol-related increase in respiratory times, suggesting a pharmacodynamic mechanism of interaction. Plasma M1 and M5 metabolites were mildly increased, contributing additionally to tramadol-related respiratory depression. Tramadol-induced early-onset increase in brain concentrations of serotonin and norepinephrine was not significantly altered by the diazepam/tramadol combination. Interestingly neither pretreatment with cyproheptadine (a serotonin-receptor antagonist) nor a benserazide/5-hydroxytryptophane combination (enhancing brain serotonin) reduced tramadol-induced seizures. Our study shows that diazepam/tramadol combination does not worsen tramadol-induced fatality risk but alters its toxicity pattern with enhanced respiratory depression but abolished seizures. Drug-drug interaction is mainly pharmacodynamic but increased plasma M1 and M5 metabolites may also contribute to enhancing respiratory depression. Tramadol-induced seizures are independent of brain serotonin.

Seizures associated with low-dose tramadol for chronic pain treatment

The management of cancer pain still poses a major challenge for clinicians. Tramadol is a centrally acting synthetic opioid analgesic. Its well-known side effects include nausea, vomiting, and dizziness; seizures are a rare side effect. Some reports have found that tramadol triggers seizure activity at high doses, whereas a few preclinical studies have found that this seizure activity is not dose-related. We herein present a case involving a patient with laryngeal cancer who developed seizures while on low-dose oral tramadol.

Evidence for neurotoxicity associated with amoxicillin in juvenile rats

Amoxicillin (AMX) is one of the most commonly prescribed antibiotics for children, and childhood is the period to have the highest risk for toxicity cases including drug-induced adverse reactions. Some neurological adverse effects (anxiety, hyperactivity, confusion, convulsions, and behavioral changes) have been reported related to AMX treatment. In the present study, we aimed to determine the neurotoxic effects of AMX administration at clinically relevant doses in female juvenile rats. AMX was administered in single oral daily doses of 25 and 50 mg/kg for 14 days. According to our results, while AMX administration caused a significant increase in the immobility time of animals, swimming time of these animals significantly decreased. AMX administration significantly reduced the onset of pentylenetetrazole-induced convulsions. The serotonin levels of brain tissues in the AMX-administered groups were decreased significantly, which is thought to be related to depression. The glutamate levels in brain tissues increased significantly in AMX-administered groups, which is thought to be related to convulsion. Otherwise, superoxide dismutase and catalase activities were significantly decreased in brain tissues of AMX-administered groups. In conclusion, AMX administration triggered depression and shortened the time of the appearance of first seizure in juvenile rats. Also, altered brain neurotransmitter levels and increased oxidative stress observed in our study were thought to be the possible underlying mechanisms of AMX-induced neurotoxicity.