Monoamine levels after pilocarpine-induced status epilepticus in hippocampus and frontal cortex of Wistar rats

Dopaminergic metabolism is affected by intracerebral injection of Tb II-I isolated from Tityus bahiensis scorpion venom

Tb II-I isolated from Tityus bahiensis venom causes epileptic-discharges when injected into the hippocampus of rats. The involvement of neurotransmitters in this activity was investigated. Our results demonstrated that Tb II-I increases the concentrations of dopamine metabolite but does not alter other neurotransmitters. Thus, dopaminergic system seems to be partially responsible for the convulsive process. Specific action on particular neurotransmitter can make this toxin a useful tool to better understand the functioning of the system.

•

The dopaminergic system is affected by intracerebral injection of Tb II-I

•

The dopaminergic system seems to be partially responsible for the convulsive process.

•

The hippocampal level of glutamate and GABA is not affected by Tb II-I

Serotonin modulation of hippocampal functions: From anatomy to neurotherapeutics

The hippocampal region receives a dense serotoninergic innervation originating from both medial and dorsal raphe nuclei. This innervation regulates hippocampal activity through the activation of distinct receptor families that are expressed in excitatory and inhibitory neurons, terminals of several afferent neurotransmitter systems, and glial cells. Preclinical and clinical studies indicate that hippocampal dysfunctions are involved in learning and memory deficits, dementia, Alzheimer's disease, epilepsy and mood disorders such as anxiety, depression and post-traumatic syndrome disorder, whereas the hippocampus participates also in the therapeutic mechanisms of numerous medicines. Not surprisingly, several drugs acting via 5-HT mechanisms are efficacious to some extent in some diseases and the link between 5-HT and the hippocampus although clear remains difficult to untangle. For this reason, we review reported data concerning the distribution and the functional roles of the 5-HT receptors in the hippocampal region in health and disease. The impact of the 5-HT systems on the hippocampal function is such that the research of new 5-HT mechanisms and drugs is still very active. It concerns notably drugs acting at the 5-HT_1A,_2A,_2C,_4,6 receptor subtypes, in addition to the already existing drugs including the selective serotonin reuptake inhibitors.

The possible neurobehavioral protective effects of natural antioxidant against phototoxicity attenuation of antimicrobial quinolone group in rats

The fluoroquinolones absorb light in the 320 to 330  nm ultraviolet A (UV-A) wavelength and produce reactive oxygen species (ROS) such as superoxide anion, hydroxyl radical, and hydrogen peroxide; thus, the photodynamic generation of ROS may be the basis of phototoxicity of quinolones in human beings and animals. This study aimed to evaluate the damaging effects of UV-A radiation at different periods of exposure on rats' brains administered with ciprofloxacin. Ciprofloxacin administration in UV-A exposed animals exaggerated the brain-oxidative stress biomarkers and decreased the locomotor activity. Exposure of rats to UV-A for 60 minutes induced a significant increase of malondialdehyde (MDA), myeloperoxidase (MPO), and a decrease in the values of superoxide dismutase (SOD), glutathione (GSH) compared to a normal one; these changes were UV-A exposure time-dependent. However, the administration of vitamin C to the UV-60-treated group decreased the values of MDA, MPO, and shifted the values of SOD, GSH toward the normal values. Vitamin C, probably due to its strong antioxidant properties, could improve and partially counteract the toxic effect of UV-A on oxidative stress parameters and prevent the damage in rat's brain tissues.

Secondary Abnormal CSF Neurotransmitter Metabolite Profiles in a Pediatric Tertiary Care Centre

BACKGROUND

Secondary neurotransmitter deficiencies have been reported in several reviews. Our primary aim was to assess the relationship among epilepsy, antiseizure medications, and specific neurotransmitter abnormalities. We also evaluated movement disorders and brain abnormalities via magnetic resonance imaging scans in patients with secondary neurotransmitter defects.

METHODS

This is a retrospective case series of 376 patients who underwent neurotransmitter analysis at BC Children's Hospital between 2009 and 2013, for a variety of neurological presentations. The biochemical genetics laboratory database was interrogated for results of cerebrospinal fluid neurotransmitter analyses. Clinical data for patients with abnormal results were collected from the hospital charts. Statistical analysis included one-way analysis of variance, chi-square, and a two-way contingency table.

RESULTS

Abnormal neurotransmitter values were identified in 67 (17.8%) patients, two (0.53%) of which were attributable to a congenital neurotransmitter disorder and 11 (16.9%) secondary to other genetic diagnoses. Of 64 patients with secondary abnormal neurotransmitter values, 38 (59%) presented with epilepsy and 20 (31%) with movement disorders. A combination of epilepsy and movement disorder was less frequent.

DISCUSSION

Acknowledging the limitations of this retrospective chart review, we conclude that, in our cohort, in addition to patients with movement disorders, a considerable number of patients with epilepsy and epileptic encephalopathy also showed secondary neurotransmitter mono-amine abnormalities. There is no clear relation, however, between clinical phenotype and type of neurotransmitter affected. In addition, no association was identified between the type of antiseizure medications and affected neurotransmitter type. We outline the need for prospective studies to further enrich our understanding of the relation between epilepsy and neurotransmitters with a focus on improving treatments and patient outcomes.

Cardamom (Elettaria cardamomum) perinatal exposure effects on the development, behavior and biochemical parameters in mice offspring

Cardamom is a strong antioxidant plant, so it is called the queen of spices. In the present study, we explored the potentials of cardamom on developmental, learning ability and biochemical parameters of mice offspring. Thirty pregnant mice were allocated to three groups of ten animals in each. Groups Π and Ш received pilsbury's Diet containing 10 and 20% of cardamom (w/w) respectively, whereas Group I used as control. Cardomom was administered from the first day of pregnancy and was continued until post-natal day 15 (PD 15) and thereafter the mothers were switched to plain pilsbury's Diet. During the weaning period, three pups in each litter were color marked from the others, and were subjected to various tests (Physical assessment such body weight and eye opening and hair appearance; the neuromaturation of reflexes like righting, rotating, and cliff avoidance reflexes; learning ability and memory retention; estimation of monoamines neurotransmitters like dopamine and serotonin, non-enzymatic oxidative stress such as TBARS and GSH in forebrain at different ages of pups). The results indicated that the body weight gain was declining significantly. Hair appearance and eyes opening were delayed significantly. Righting, rotating, and cliff avoidance reflexes were delayed in treated animals. Exposure to cardamom led to enhance learning and memory retention as compared to control. Monoamines (DA, 5-HT) and GSH were elevated, whereas TBARS was inhibited significantly. In conclusion, perinatal cardamom exposure enhanced learning and memory as compared to control. Cardamom and its benefit compounds were transported via placenta or/and milk during lactation. Cardamom needs more researches to investigate its benefits on other kinds of behavior.

The effects of quinacrine, proglumide, and pentoxifylline on seizure activity, cognitive deficit, and oxidative stress in rat lithium-pilocarpine model of status epilepticus

The present data indicate that status epilepticus (SE) induced in adult rats is associated with cognitive dysfunctions and cerebral oxidative stress (OS). This has been demonstrated using lithium-pilocarpine (Li-Pc) model of SE. OS occurring in hippocampus and striatum of mature brain following SE is apparently due to both the increased free radicals production and the limited antioxidant defense. Pronounced alterations were noticed in the enzymatic, glutathione-S transferase (GST), catalase (CAT), and superoxide dismutase (SOD), as well as in the nonenzymatic; thiobarbituric acid (TBARS) and reduced glutathione (GST), indices of OS in the hippocampus and striatum of SE induced animals. Quinacrine (Qcn), proglumide (Pgm), and pentoxifylline (Ptx) administered to animals before inducing SE, were significantly effective in ameliorating the seizure activities, cognitive dysfunctions, and cerebral OS. The findings suggest that all the drugs were effective in the order of Ptx < Pgm < Qcn indicating that these drugs are potentially antiepileptic as well as antioxidant; however, further studies are needed to establish this fact. It can be assumed that these antiepileptic substances with antioxidant properties combined with conventional therapies might provide a beneficial effect in treatment of epilepsy through ameliorating the cerebral OS.

Cognitive and biochemical effects of monosodium glutamate and aspartame, administered individually and in combination in male albino mice

The present study was designed to investigate the in vivo effects of monosodium glutamate (MSG) and aspartame (ASM) individually and in combination on the cognitive behavior and biochemical parameters like neurotransmitters and oxidative stress indices in the brain tissue of mice. Forty male Swiss albino mice were randomly divided into four groups of ten each and were exposed to MSG and ASM through drinking water for one month. Group I was the control and was given normal tap water. Groups II and III received MSG (8 mg/kg) and ASM (32 mg/kg) respectively dissolved in tap water. Group IV received MSG and ASM together in the same doses. After the exposure period, the animals were subjected to cognitive behavioral tests in a shuttle box and a water maze. Thereafter, the animals were sacrificed and the neurotransmitters and oxidative stress indices were estimated in their forebrain tissue. Both MSG and ASM individually as well as in combination had significant disruptive effects on the cognitive responses, memory retention and learning capabilities of the mice in the order (MSG+ASM)>ASM>MSG. Furthermore, while MSG and ASM individually were unable to alter the brain neurotransmitters and the oxidative stress indices, their combination dose (MSG+ASM) decreased significantly the levels of neurotransmitters (dopamine and serotonin) and it also caused oxidative stress by increasing the lipid peroxides measured in the form of thiobarbituric acid-reactive substances (TBARS) and decreasing the level of total glutathione (GSH). Further studies are required to evaluate the synergistic effects of MSG and ASM on the neurotransmitters and oxidative stress indices and their involvement in cognitive dysfunctions.

Protective effects of curcumin against lithium-pilocarpine induced status epilepticus, cognitive dysfunction and oxidative stress in young rats

Status epilepticus (SE), one of the most severe forms of epilepsy is regarded a medical emergency with considerable morbidity and mortality. Due to the limited efficacy and enormous side effects of currently available drugs, a search for new safe and effective therapeutic agents is critical using experimentally induced SE in animals. The lithium-pilocarpine (Li-Pc) model of SE is most suitable and frequently used for pathophysiological and management strategies of SE. Recent studies have shown significant potential of pharmacological, prophylactic or therapeutic use of curcumin (Cur) in many beneficial activities in the body including neuroprotection in neurodegenerative diseases and antioxidant properties. The present study describes anticonvulsive effects of Cur in Li-Pc induced SE in young rats. The effect of Cur was examined on the intensity and frequency of SE, cognitive behavior in water maze as well as on oxidative stress related enzymes in the brain. Besides its anticonvulsant effect, Cur significantly ameliorates SE-induced cognitive dysfunction and oxidative damages in the hippocampus and striatum areas of the brain. Possible therapeutic application of Cur as an anticonvulsant and as an antioxidant for the treatment of SE has a great potential and warrants further studies.

Seizure-induced 5-HT release and chronic impairment of serotonergic function in rats

We analyzed the dynamic concentration change of serotonin (5-HT) and its main metabolite 5-hydroxyindoleacetic acid (5-HIAA) within the epileptic hippocampus in rats. Seizure was induced by systemic injection of pilocarpine (320mg/kg, i.p.). Using electroencephalography (EEG) recordings, we found that primary seizure discharge was induced 30min after pilocarpine administration and that recurrent discharge peaked 14d after the onset of status epilepticus (SE). The extracellular fluid in the hippocampus was sampled by microdialysis from conscious animals at various time points before and after SE. The concentrations of 5-HT and 5-HIAA in the samples were measured by high-performance liquid chromatography and electrochemical detection (HPLC-ECD). Interestingly, 5-HT levels in the hippocampus were dramatically increased within the 30min following SE. This reversed to basal level by 4d after SE and continued to drop to 48% at 7d and 28% of basal level 14d after SE. Accordingly, a marked increase of 5-HIAA in the hippocampus appeared at 2d after SE, then gradually declined to levels below baseline. To identify serotonergic neurons in the raphe nuclei (a major source of 5-HT release in the brain), brain sections were immunostained for tryptophan hydroxylase (TPH). The number of TPH positive neurons and the intensity of TPH staining significantly decreased at 28d after SE. These data suggest that pilocarpine induces depletion of 5-HT in the hippocampus and significantly compromise serotonergic neurons in the raphe nuclei. The loss of serotonergic function may play a significant role in the pathophysiology of epilepsy.

Impaired maturation of serotonergic function in the dentate gyrus associated with epilepsy

Temporal lobe epilepsy is believed to develop after an initial precipitating injury, usually suffered in childhood or adolescence, and aspects include impaired maturation of the hippocampus, and specifically the dentate gyrus. The dentate gyrus receives a major serotonergic input from the brainstem raphe nuclei, and the serotonergic system may regulate neurogenesis in the developing and mature hippocampus. The aim of this work was to investigate changes which may be associated with abnormal functioning of the serotonergic system in the pilocarpine model of epilepsy, where spontaneous seizures are induced by administration of pilocarpine at 6 weeks of age. Application of serotonin (100 μM) led to a transient hyperpolarization of the resting membrane potential and decrease of the input resistance mediated by the 5-HT(1A) receptor that was similar between control and pilocarpine-treated animals and unaffected by the age of the animal. In the younger, but not in older control animals, serotonin led to a 5-HT(2) receptor-mediated long-term depression of evoked postsynaptic currents, a normal functional shift in the early adulthood of the Wistar rat. In pilocarpine-treated animals, this long-term depression persisted in older animals, indicating impaired maturation of the dentate gyrus. These data may indicate 5-HT(2) receptor function to be affected by the pathology of temporal lobe epilepsy.

Lipoic acid effects on glutamate and taurine concentrations in rat hippocampus after pilocarpine-induced seizures

Pilocarpine-induced seizures can be mediated by increases in oxidative stress and by cerebral amino acid changes. The present research suggests that antioxidant compounds may afford some level of neuroprotection against the neurotoxicity of seizures in cellular level. The objective of the present study was to evaluate the lipoic acid (LA) effects in glutamate and taurine contents in rat hippocampus after pilocarpine-induced seizures. Wistar rats were treated intraperitoneally (i.p.) with 0.9% saline (Control), pilocarpine (400 mg/kg, Pilocarpine), LA (10 mg/kg, LA), and the association of LA (10 mg/kg) plus pilocarpine (400 mg/kg), that was injected 30 min before of administration of LA (LA plus pilocarpine). Animals were observed during 24 h. The amino acid concentrations were measured using high-performance liquid chromatograph (HPLC). In pilocarpine group, it was observed a significant increase in glutamate content (37%) and a decrease in taurine level (18%) in rat hippocampus, when compared to control group. Antioxidant pretreatment significantly reduced the glutamate level (28%) and augmented taurine content (32%) in rat hippocampus, when compared to pilocarpine group. Our findings strongly support amino acid changes in hippocampus during seizures induced by pilocarpine, and suggest that glutamate-induced brain damage plays a crucial role in pathogenic consequences of seizures, and imply that strong protective effect could be achieved using lipoic acid through the release or decrease in metabolization rate of taurine amino acid during seizures.

Effects of oxcarbazepine on monoamines content in hippocampus and head and body shakes and sleep patterns in kainic acid-treated rats

The aim of this work was to analyze the effect of oxcarbazepine (OXC) on sleep patterns, "head and body shakes" and monoamine neurotransmitters level in a model of kainic-induced seizures. Adult Wistar rats were administered kainic acid (KA), OXC or OXC + KA. A polysomnographic study showed that KA induced animals to stay awake for the whole initial 10 h. OXC administration 30 min prior to KA diminished the effect of KA on the sleep parameters. As a measure of the effects of the drug treatments on behavior, head and body shakes were visually recorded for 4 h after administration of KA, OXC + KA or saline. The presence of OXC diminished the shakes frequency. 4 h after drug application, the hippocampus was dissected out, and the content of monoamines was analyzed. The presence of OXC still more increased serotonin, 5-hidroxyindole acetic acid, dopamine, and homovanilic acid, induced by KA.

Lipoic acid effects on monoaminergic system after pilocarpine-induced seizures

Systemic injection of pilocarpine has been shown to induce recurrent seizures and epileptic discharges demonstrated by EEG monitoring. It also has been reported that antioxidants are able to diminish or prevent the occurrence of epileptic discharges induced by pilocarpine through the inhibition of free radical formation and neurotransmitter metabolic alterations. The purpose of this work was to determine the effects of lipoic acid (LA) on the levels of dopamine (DA), serotonin (5-HT), norepinephrine (NE) and subsequent metabolites in the hippocampus of rats after seizure induction by pilocarpine. Seizures dramatically decreased the levels of DA, 5-hydroxyindoleacetic acid (5-HIAA) and NE, whereas significantly increased the levels of neurotransmitter metabolites. The administration of lipoic acid before seizure induction resulted in normalized levels of DA and 5-HA. However, the lipoic acid administration in similar conditions produced a reduction of the metabolites levels when compared with the pilocarpine group. These results suggest that the establishment of acute phase of seizures induced by pilocarpine might be produced by consequent the activation of serotonergic neurons. In addition, the lipoic acid inhibits hyperactivity of this system during the installation of pilocarpine-induced seizures.

Neonatal status epilepticus alters prefrontal-striatal circuitry and enhances methamphetamine-induced behavioral sensitization in adolescence

Neonatal seizures may alter the developing neurocircuitry and cause behavioral abnormalities in adulthood. We found that rats previously subjected to lithium-pilocarpine (LiPC)-induced neonatal status epilepticus (NeoSE) exhibited enhanced behavioral sensitization to methamphetamine (MA) in adolescence. Neurochemically, dopamine (DA) and metabolites were markedly decreased in prefrontal cortex (PFC) and insignificantly changed in striatum by NeoSE, but were increased in both PFC and striatum by NeoSE+MA. Glutamate levels were increased in both PFC and striatum in the NeoSE+MA group. DA turnover, an index of utilization and activity, was increased by NeoSE but reversed by MA in PFC. Gene expression of the regulator of G-protein signaling 4 (RGS4) was downregulated in PFC and striatum by NeoSE and further suppressed by MA. These findings suggest NeoSE affects both dopaminergic and glutamatergic systems in the prefrontal-striatal circuitry that manifests as enhanced behavioral sensitization to MA in adolescence.

Pentoxifylline ameliorates lithium-pilocarpine induced status epilepticus in young rats

The neuroprotective effects of pentoxifylline (PTX) against lithium-pilocarpine (Li-Pc)-induced status epilepticus (SE) in young rats are described. Animals treated with PTX (0, 20, 40, and 60 mg/kg) before induction of SE were examined for latency to and frequency of SE, behavioral changes, oxidative stress, neurochemical alterations in the hippocampus and striatum, and histological abnormalities in the hippocampus. Treatment with PTX significantly ameliorated the frequency and severity of epileptic seizures in a dose-dependent manner. Our behavioral studies using the elevated plus-maze, rotarod, and water maze tests suggested a significant reduction in anxiety, enhanced motor performance, and improved learning and memory in PTX-treated rats. Li-Pc-induced neuronal cell loss and sprouting of mossy fibers in the hippocampus were also attenuated by PTX. The neuroprotective activity of PTX was accompanied by reduction in oxidative stress and reversal of SE-induced depletion of dopamine and 5-hydroxytryptamine in hippocampus and striatum. The results of this study provide a good rationale to explore the prophylactic/therapeutic potential of PTX in SE.

Study pharmacologic of the GABAergic and glutamatergic drugs on seizures and status epilepticus induced by pilocarpine in adult Wistar rats

This work was designed to study the influence of drugs during seizures and status epilepticus (SE) induced by pilocarpine and mortality in adult rats. Glutamate (10 and 20 mg/kg), N-methyl-d-aspartate (NMDA, 5 and 10 mg/kg), ketamine (1.5 and 2.0 mg/kg), gabapentin (200 and 250 mg/kg), phenobarbital (50 and 100 mg/kg) and vigabatrin (250 and 500 mg/kg) were administered intraperitoneally, 30 min prior to pilocarpine (400 mg/kg, i.p.). The animals were observed (24 h) to determine: number of peripheral cholinergic signs, tremors, stereotyped movements, seizures, SE, latency to first seizure and number of deaths after pilocarpine treatment. NMDA and glutamate had pro-convulsive effects in both doses tested. Smaller and higher doses of these drugs no protected and increased pilocarpine-induced seizures and/or mortality. Gabapentin, vigabatrin, phenobarbital and ketamine protected against seizures and increased the latency to first seizure. Thus, these results suggest that caution should be taken in the selection of pharmacotherapy and dosages for patients with seizures and SE because of the possibility of facility the convulsive process toxicity, SE and the mortality of adult animals in this seizures model that is similar temporal lobo epilepsy in humans.

Amelioration of water maze performance deficits by topiramate applied during pilocarpine-induced status epilepticus is negatively dose-dependent

Temporal lobe epilepsy is characterized by a progressive loss of memory capacities, due to sclerosis and functional impairment of mesiotemporal brain areas. We have shown recently that topiramate (TPM) dose-dependently protects hippocampal CA1 and CA3 neurons during initial status epilepticus in the rat pilocarpine model of temporal lobe epilepsy by inhibition of mitochondrial transition pore opening. In the present study, in order to evaluate possible positive effects of the treatment on learning and memory, we investigated water maze performance of rats receiving different dosages of TPM (20 and 100 mg/kg) after 40 min and 4 mg/kg diazepam after 160 min of pilocarpine-induced status epilepticus in relation to performance of animals receiving 4 mg/kg diazepam after 40 min of SE, and to performance of sham-treated control animals. Unexpectedly, 20 but not 100 mg/kg TPM significantly extenuated short-term memory deficits. While neuroprotective effects of TPM were observed in hippocampal CA subfields of animals treated with 100 mg/kg TPM, cell loss in rats treated with 20 mg/kg TPM was indistinguishable from animals receiving diazepam only. The present results indicate a negative dose-dependency of memory-saving effects of TPM applied during status epilepticus apparently dissociated from hippocampal neuroprotection.

Pharmacological studies of the opioids, mood stabilizer and dopaminergic drugs on pilocarpine-induced seizures and status epilepticus

This work was designed to study the influence of drugs during seizures and status epilepticus (SE) induced by pilocarpine and mortality in adult rats. Morphine (0.1 and 0.2 mg/kg), SCH 23390 (0.1 and 0.2 mg/kg), haloperidol (5 and 10mg/kg) and lithium (30 and 60 mg/kg) were administered intraperitoneally (i.p.), 30 min before to pilocarpine (400 mg/kg, s.c.). The animals were observed (24 h) to determine: number of peripheral cholinergic signs, tremors, stereotyped movements, seizures, SE, latency to first seizure and number of deaths after pilocarpine treatment. Morphine and haloperidol had proconvulsant effects in both doses tested. Smaller and higher doses of these drugs no protected and increased pilocarpine-induced seizures, SE and/or mortality. SCH 23390 protected against seizures, increased the latency to first seizure and reduced the mortality of the animals treated with pilocarpine Theses results suggest that dopamine receptor system receptor subtypes exert opposite functions on the regulation of convulsive activity. The morphine is proconvulsant in lower doses. The opioids in high doses tested exert an action proconvulsant during the establishment of epileptic activity induce by pilocarpine. The lithium no protected the animals against seizures induced by pilocarpine and is used which a model of epilepsy associated with lower doses of pilocarpine in several studies, suggesting absence of the effect anticonvulsants in rodents.

Effect of gabaergic, glutamatergic, antipsychotic and antidepressant drugs on pilocarpine-induced seizures and status epilepticus

This work was designed to study the influence of drugs during seizures and status epilepticus (SE) induced by pilocarpine and mortality in adult rats. Fluoxetine (10 and 20 mg/kg), NMDA (N-methyl-D-aspartate, 10 and 20 mg/kg), amitriptyline (25 and 50 mg/kg), ketamine (0.5 and 1.0 mg/kg), gabapentin (100 and 150 mg/kg) and pimozide (10 and 20 mg/kg) were administered intraperitoneally, 30 min prior to pilocarpine (400mg/kg, s.c.). The animals were observed (24h) to determine: number of peripheral cholinergic signs, tremors, stereotyped movements, seizures, SE, latency to first seizure and number of deaths after pilocarpine treatment. Fluoxetine, amitriptyline, NMDA, and pimozide had proconvulsant effects in both doses tested. Smaller and higher doses of these drugs no protected and increased pilocarpine-induced seizures and/or mortality. Gabapentin and ketamine protected against seizures and reduced the latency to first seizure. Thus, these results suggest that caution should be taken in the selection of pharmacotherapy and dosages for patients with epilepsy because of the possibility of potentiating convulsive process toxicity.