Guanosine treatment prevents lipopolysaccharide-induced depressive-like behavior in mice.

Guanosine is a purinergic nucleoside that has been shown to have neuroprotective effects, mainly through its ability to modulate the glutamatergic system. An increase in pro-inflammatory cytokine levels triggers the activation of the enzyme indoleamine 2,3-dioxygenase 1 (IDO-1), leading to glutamatergic excitotoxicity, which has important roles in the pathophysiology of depression. The aim of this study was to investigate the possible antidepressant-like effects and underlying mechanisms of action of guanosine against lipopolysaccharide (LPS)-induced depression in a mouse model. Mice were orally pre-treated with saline (0.9% NaCl), guanosine (8 or 16 mg/kg), or fluoxetine (30 mg/kg) for 7 days before LPS (0.5 mg/kg, intraperitoneal) injection. One day after LPS injection, mice were subjected to the forced swim test (FST), tail suspension test (TST), and open field test (OFT). After the behavioral tests, mice were euthanized and the levels of tumor necrosis factor-α (TNF-α), IDO-1, glutathione, and malondialdehyde in the hippocampus were measured. Pretreatment with guanosine was able to prevent LPS- induced depressive-like behaviors in the TST and FST. In the OFT, no locomotor changes were observed with any treatment. Both guanosine (8 and 16 mg/kg/day) and fluoxetine treatment prevented the LPS-induced increase in TNF-α and IDO expression and lipid peroxidation as well as decrease of reduced glutathione levels in the hippocampus. Taken together, our findings suggest that guanosine may have neuroprotective effects against LPS-induced depressive-like behavior through preventing oxidative stress and the expression of IDO-1 and TNF-α in the hippocampus.

Involvement of kynurenine pathway and N-methyl-d-aspartate receptors in the antidepressant-like effect of vilazodone in the tail suspension test in mice.

The present study evaluated the antidepressant-like effects of vilazodone using the tail suspension test in mice. We also investigated the contribution of kynurenine pathway and N-methyl-d-aspartate receptors to this effect. For this purpose, we pretreated animals with sub-effective doses of L-kynurenine, 3-hydroxykynurenine, or quinolinic acid. We then assessed the immobility time, an indicative measure of depressive-like behavior, in the tail suspension test. We also evaluated the possible effects of sub-effective doses of vilazodone combined with sub-effective doses of ketamine (N-methyl-d-aspartate receptor antagonist) in a separate group. Vilazodone (3mg/kg, intraperitoneal) significantly reduced immobility time in the tail suspension test. L-kynurenine (1.7 mg/kg, intraperitoneal), 3-hydroxykynurenine (10 mg/kg, intraperitoneal), and quinolinic acid (3 nmol/site, intracerebroventricular) significantly increased the immobility time in the tail suspension test. The antidepressant-like effects of vilazodone (3mg/kg, intraperitoneal) were inhibited by pre-treatment with non-effective doses of L-kynurenine (0.83 mg/kg, intraperitoneal), 3-hydroxykynurenine (3.33 mg/kg, intraperitoneal), or quinolinic acid (1 nmol/site, intracerebroventricular). Pretreatment of mice with sub-effective doses of ketamine (1 mg/kg, intraperitoneal) optimized the action of a sub-effective dose of vilazodone (0.3mg/kg, intraperitoneal) and reduced the immobility time in the tail suspension test. None of the drugs used in this study induced any changes in locomotor activity in the open field test. The results showed that vilazodone induced an antidepressant-like effect in the tail suspension test, which may be mediated through an interaction with the kynurenine pathway and N-methyl-d-aspartate receptors.

Long-term monotherapy treatment with vitamin E reduces oxidative stress, but not seizure frequency in rats submitted to the pilocarpine model of epilepsy.

The imbalance between antioxidant system and reactive oxygen species (ROS) generation is related to epileptogenesis, neuronal death, and seizure frequency. Treatment with vitamin E has been associated with neuroprotection and control of seizures. In most experimental studies, vitamin E treatment has short duration. Therefore, the aim of this study was to verify the role of long-term treatment with vitamin E in rats submitted to the pilocarpine model of epilepsy. Rats were divided into two main groups: control (Ctr) and pilocarpine (Pilo). Each one was subdivided according to treatment: vehicle (Ctr V and Pilo V) or vitamin E at dosages of 6 IU/kg/day (Ctr E6 and Pilo E6) or 60 IU/kg/day (Ctr E60 and Pilo E60). Treatment lasted 120 days from status epilepticus (SE). There were no statistical differences concerning treatment in the Ctr group for all variables, so the data were grouped. Carbonyl content in the hippocampus of Pilo V and Pilo E6 was higher compared with that of the Ctr group (8 ±â€¯1.5, 7.1 ±â€¯1, and 3.1 ±â€¯0.3 nmol carbonyl/mg protein, respectively for Pilo V, Pilo E6, and Ctr; p < 0.05). Carbonyl content was restored to control values in Pilo E60 rats (4.2 ±â€¯1.1 and 3.1 ±â€¯0.3 nmol carbonyl/mg protein, respectively for Pilo E60 and Ctr; p > 0.05). The volume of the hippocampal formation (6.5 ±â€¯0.3, 6.6 ±â€¯0.4, 6.3 ±â€¯0.3, and 7.4 ±â€¯0.2, respectively for Pilo V, Pilo E6, Pilo E60, and Ctr) and subfields CA1 (1.6 ±â€¯0.1, 1.4 ±â€¯0.2, 1.5 ±â€¯0.1, and 2 ±â€¯0.05, respectively for Pilo V, Pilo E6, Pilo E60, and Ctr) and CA3 (1.7 ±â€¯0.1, 1.5 ±â€¯0.2, 1.4 ±â€¯0.1, and 2 ±â€¯0.1, respectively for Pilo V, Pilo E6, Pilo E60, and Ctr) was reduced in the Pilo group regardless of treatment. Parvalbumin immunostaining was increased in the hilus of the Pilo E60 group compared with that in the Ctr group (26 ±â€¯2 and 39.6 ±â€¯8.3 neurons, respectively for Ctr and Pilo E60). No difference was found in seizure frequency and Neo-Timm staining. Therefore, long-term treatment with 60 IU/kg/day of vitamin E prevented oxidative damage in the hippocampus and increased hilar parvalbumin expression in rats with epilepsy without a reduction in seizure frequency.

Altered MT1 and MT2 melatonin receptors expression in the hippocampus of pilocarpine-induced epileptic rats.

Clinical and experimental findings show that melatonin may be used as an adjuvant to the treatment of epilepsy-related complications by alleviates sleep disturbances, circadian alterations and attenuates seizures alone or in combination with AEDs. In addition, it has been observed that there is a circadian component on seizures, which cause changes in circadian system and in melatonin production. Nevertheless, the dynamic changes of the melatoninergic system, especially with regard to its membrane receptors (MT1 and MT2) in the natural course of TLE remain largely unknown. The aim of this study was to evaluate the 24-hour profile of MT1 and MT2 mRNA and protein expression in the hippocampus of rats submitted to the pilocarpine-induced epilepsy model analyzing the influence of the circadian rhythm in the expression pattern during the acute, silent, and chronic phases. Melatonin receptor MT1 and MT2 mRNA expression levels were increased in the hippocampus of rats few hours after SE, with MT1 returning to normal levels and MT2 reducing during the silent phase. During the chronic phase, mRNA expression levels of both receptors return to levels close to control, however, presenting a different daily profile, showing that there is a circadian change during the chronic phase. Also, during the acute and silent phase it was possible to verify MT1 label only in CA2 hippocampal region with an increased expression only in the dark period of the acute phase. The MT2 receptor was present in all hippocampal regions, however, it was reduced in the acute phase and it was found in astrocytes. In chronic animals, there is a reduction in the presence of both receptors especially in regions where there is a typical damage derived from epilepsy. Therefore, we conclude that SE induced by pilocarpine is able to change melatonin receptor MT1 and MT2 protein and mRNA expression levels in the hippocampus of rats few hours after SE as well as in silent and chronic phases.

Pilocarpine-induced epilepsy alters the expression and daily variation of the nuclear receptor RORα in the hippocampus of rats.

It is widely known that there is an increase in the inflammatory responses and oxidative stress in temporal lobe epilepsy (TLE). Further, the seizures follow a circadian rhythmicity. Retinoic acid receptor-related orphan receptor alpha (RORα) is related to anti-inflammatory and antioxidant enzyme expression and is part of the machinery of the biological clock and circadian rhythms. However, the participation of RORα in this neurological disorder has not been studied. The aim of this study was to evaluate the RORα mRNA and protein content profiles in the hippocampus of rats submitted to a pilocarpine-induced epilepsy model at different time points throughout the 24-h light-dark cycle analyzing the influence of the circadian rhythm in the expression pattern during the acute, silent, and chronic phases of the experimental model. Real-time PCR and immunohistochemistry results showed that RORα mRNA and protein expressions were globally reduced in both acute and silent phases of the pilocarpine model. However, 60days after the pilocarpine-induced status epilepticus (chronic phase), the mRNA expression was similar to the control except for the time point 3h after the lights were turned off, and no differences were found in immunohistochemistry. Our results indicate that the status epilepticus induced by pilocarpine is able to change the expression and daily variation of RORα in the rat hippocampal area during the acute and silent phases. These findings enhance our understanding of the circadian pattern present in seizures as well as facilitate strategies for the treatment of seizures.

Asma: Idade de Surgimento Pode ser um Fator para o Aumento da Prevalência / Asthma: Age of Onset May be a Factor for the Increased Prevalence

A asma é uma das doenças crônicas mais comuns na população infantil e o aumento da sua prevalência tem se tornado foco de muitas pesquisas epidemiológicas. Nas últimas décadas, observou-se aumento de aproximadamente 50% em sua prevalência, com índices diferentes entre os continentes. Desta forma, o objetivo desse estudo foi fazer uma revisão bibliográfica a respeito da prevalência e idade de surgimento da asma. A presente revisão faz uma abordagem sobre a prevalência, idade de surgimento e fatores de risco em crianças com asma. Foram consultados artigos científicos indexados nas Bases de Dados Scientific Electronic Library Online - SCIELO), Literatura Latino-Americana e do Caribe em Ciências da Saúde - LILACS, e PubMed, utilizando como descritores: asma, surgimento da asma, fatores de risco para asma. Os critérios de elegibilidade foram estudos que apresentassem dados referentes à prevalência da asma, idade de surgimento e fatores de risco para o desenvolvimento, preconizados entre os anos de 1990 até os mais atuais de 2014. As manifestações clínicas surgem, geralmente, na população infantil abaixo de 5 anos de vida, portanto maior atenção individualizada pelos profissionais de saúde deve ser dada às crianças com prováveis diagnósticos de asma, a fim de se propor condutas e estabelecer prognósticos.

Asthma is one of the most common chronic diseases among child population; the increase in its prevalence has become the focus of much epidemiologic research. In recent decades, it was observed an increase of approximately 50% in its prevalence, with different indices among the continents. In this way, the object of our study was making a bibliographic review about the prevalence and the age of onset. This review takes a relevant approach about the prevalence, the age of onset and the risk factors in children with asthma. The research was conducted through a bibliographic review on scientific articles in databases Scientific Electronic Library Online - SciELO, Latin-american and Caribbean Health Sciences - LILACS and PubMed, using as descriptors: asthma, asthma onset, asthma risk factors. The eligibility criteria were studies presenting data relating to asthma prevalence, age of onset, and risk factors, preconized from 1990 to 2014. Clinical manifestations appear usually in the child population under 5 years old, thus, more individualized attention by healthcare professionals must be given to children with probable diagnosis of asthma in order to propose conducts and establish prognostics.

Malnutrition in infancy as a susceptibility factor for temporal lobe epilepsy in adulthood induced by the pilocarpine experimental model.

Malnutrition during the earliest stages of life may result in innumerable brain problems. Moreover, this condition could increase the chances of developing neurological diseases, such as epilepsy. We analyzed the effects of early-life malnutrition on susceptibility to epileptic seizures induced by the pilocarpine model of epilepsy. Wistar rat pups were kept on a starvation regimen from day 1 to day 21 after birth. At day 60, 16 animals (8 = well-nourished; 8 = malnourished) were exposed to the pilocarpine experimental model of epilepsy. Age-matched well-nourished (n = 8) and malnourished (n = 8) rats were used as controls. Animals were video-monitored over 9 weeks. The following behavioral parameters were evaluated: first seizure threshold (acute period of the pilocarpine model); status epilepticus (SE) latency; first spontaneous seizure latency (silent period), and spontaneous seizure frequency during the chronic phase. The cell and mossy fiber sprouting (MFS) density were evaluated in the hippocampal formation. Our results showed that the malnourished animals required a lower pilocarpine dose in order to develop SE (200 mg/kg), lower latency to reach SE, less time for the first spontaneous seizure and higher seizure frequency, when compared to well-nourished pilocarpine rats. Histopathological findings revealed a significant cell density reduction in the CA1 region and intense MFS among the malnourished animals. Our data indicate that early malnutrition greatly influences susceptibility to seizures and behavioral manifestations in adult life. These findings suggest that malnutrition in infancy reduces the threshold for epilepsy and promotes alterations in the brain that persist into adult life.

Seizures during pregnancy modify the development of hippocampal interneurons of the offspring.

We investigated the effect of epileptic seizures during pregnancy on hippocampal expression of calcium-binding proteins in the offspring. Female Wistar rats were submitted to the pilocarpine model and mated during the chronic period. Seizure frequency was monitored over the entire pregnancy. Pups were perfused at postnatal days 6 and 13, and the brains processed for Nissl staining and immunohistochemistry for NeuN, calbindin, calretinin, and parvalbumin. Number of stained cells in the hippocampus was estimated through stereological methods. Our results showed a decrease in epileptic seizure frequency during pregnancy. No differences were observed in NeuN-positive, CR-positive cells, and Nissl-stained hippocampal neurons between the groups. However, there was a significant decrease in calbindin-positive cells (P=0.005) and a significant increase in parvalbumin-positive cells (P=0.02) in the experimental group when compared with the control group. These results suggest that seizures during pregnancy affect the development of specific hippocampal interneurons of the offspring.

Melatonin treatment decreases c-fos expression in a headache model induced by capsaicin.

The aim of the present work was to analyze c-fos response within the trigeminal nucleus caudalis (TNC) of pinealectomized rats and animals that received intraperitoneal melatonin, after intracisternal infusion of capsaicin, used to induce intracranial trigeminovascular stimulation. Experimental groups consisted of animals that received vehicle solution (saline-ethanol-Tween 80, 8:1:1, diluted 1:50) only (VEI, n=5); animals that received capsaicin solution (200 nM) only (CAP, n=6); animals submitted to pinealectomy (PX, n=5); sham-operated animals (SH, n=5); animals submitted to pinealectomy followed by capsaicin stimulation (200 nM) after 15 days (PX + CAP, n=7); and animals that received capsaicin solution (200 nM) and intraperitoneal melatonin (10 mg/kg) (CAP + MEL, n=5). Control rats, receiving vehicle in the cisterna magna, showed a small number of c-fos-positive cells in the TNC (layer I/II) as well as the sham-operated and pinealectomized rats, when compared to animals stimulated by capsaicin. On the other hand, pinealectomized rats, which received capsaicin, presented the highest number of c-fos-positive cells. Animals receiving capsaicin and melatonin treatment had similar expression of the vehicle group. Our data provide experimental evidence to support the role of melatonin and pineal gland in the pathophysiology of neurovascular headaches.

Cardiovascular protective effect of melatonin in sudden unexpected death in epilepsy: a hypothesis.

Epilepsy is the most common neurological disorder, approximately 1% of the population worldwide have epilepsy. Moreover, sudden unexpected death in epilepsy (SUDEP) is the most important direct epilepsy-related cause of death. Information concerning risk factors for SUDEP is conflicting, but potential risk factors include: age, early onset of epilepsy, duration of epilepsy, uncontrolled seizures, seizure frequency, AED number and winter temperatures. Additionally, the cause of SUDEP is still unknown; however, the most commonly suggested mechanisms are cardiac abnormalities during and between seizures. Furthermore, the evidence from the last 10 years suggests that melatonin has an important role in the epileptogenesis process and influences the cardiovascular system as well. The positive effect of melatonin has been demonstrated against different convulsive stimuli in several rodents, including seizures induced by pentylenetetrazole kainate, glutamate, maximal electrical shock and electrically kindled stimulation of amygdala. Clinical studies have also demonstrated a positive role of melatonin on the seizure frequency in children and reduced spiking activity and seizure frequency in patients with intractable epilepsy. In the rat hearts, studies in vivo and in vitro using pharmacological concentrations of melatonin confirmed an anti-arrhythmic effect of this hormone and studies in humans have been shown that chronic heart disease patients have significantly lower melatonin levels in their blood stream than do normal individuals. Thus, caution should be taken in generalization of these findings to epileptic population. Moreover, it is important to note that when dealing with intractable epilepsy that do not respond to any conventional treatment, the additional of melatonin may be evaluated. Taken together, in this paper we suggested a possible relationship between cardiac abnormalities, melatonin and SUDEP.

Effects of pinealectomy and the treatment with melatonin on the temporal lobe epilepsy in rats.

The aim of the present work was to analyze the effects of pinealectomy in the development of the epilepsy model induced by pilocarpine in adult male rats. Group I: Wistar male adult rats were submitted to pinealectomy, and 7 days after surgery, these animals received pilocarpine (350 mg/kg, i.p.) to induce three distinct behavioral phases: status epilepticus, seizure-free, and chronic phases. This late, as well as all control groups were continuously video-recorded for 60 days, to study behavior parameters. These animals were killed and the brain sections were processed for Nissl and neo-Timm. Group II: Another group, also submitted to pinealectomy, received several injections of melatonin (2.5 mg/kg): 20 min before, concomitantly with pilocarpine, 30 min, 1 h, and 2 h after pilocarpine administration. Some animals from group I and all from group II were sacrificed 48 h following status epilepticus onset to perform TUNEL assay. The latency for status epilepticus onset, status epilepticus length as well as mortality rate during status epilepticus were similar for pinealectomized and control groups. On the other hand, pinealectomized rats presented minor duration of the silent period, a higher number of spontaneous seizures during the chronic phase, increased number of TUNEL-positive cells (acute phase), increased neuronal loss, and marked supragranullar mossy fibers sprouting (chronic phase) in the hippocampal formation, when compared with control groups. Our data show that the pinealectomy facilitates the epileptogenic process that follows the long-lasting status epilepticus. This facilitation can be partially reverted by the simultaneous administration of melatonin.