Imipramine reverses depressive-like parameters in pneumococcal meningitis survivor rats.

Pneumococcal meningitis is a severe infectious disease of the central nervous system, associated with acute inflammation and might cause damage to the host, such as deafness, blindness, seizure, and learning deficits. However, infectious diseases can play a significant role in the etiology of neuropsychiatric disturbances. In this context, we evaluated depressive-like parameters; corticosterone and ACTH levels in pneumococcal meningitis surviving rats. Wistar rats underwent a magna cistern tap receiving either 10 µL sterile saline or a Streptococcus pneumoniae suspension at the concentration of 5 × 10(9) cfu/mL. After 3 days of meningitis induction procedure, the animals were treated with imipramine at 10 mg/kg or saline for 14 days (3rd-17th day). The consumption of sweet food was measured for 7 days (10th-17th day). The meningitis group decreased the sucrose intake and increased the levels of corticosterone and ACTH levels in the serum and TNF-α in the cortex; however, the treatment with imipramine reverted the reduction of sweet food consumption, normalized hormonal levels and TNF-α in the cortex. Our results supported the hypothesis that the pneumococcal meningitis surviving rats showed depressive-like behavior and alterations in the hypothalamus-pituitary-adrenal axis.

Acetylcholinesterase activity in the rat brain after pneumococcal meningitis.

Pneumococcal meningitis is a life-threatening disease characterized by acute purulent infection of the meninges causing neuronal injury, cortical necrosis and hippocampal apoptosis. Cholinergic neurons and their projections are extensively distributed throughout the central nervous system. The aim of this study was to assess acetylcholinesterase activity in the rat brain after pneumococcal meningitis. In the hippocampus, frontal cortex and cerebrospinal fluid, acetylcholinesterase activity was found to be increased at 6, 12, 24, 48 and 96 hr without antibiotic treatment, and at 48 and 96 hr with antibiotic treatment. Our data suggest that acetylcholinesterase activity could be related to neuronal damage induced by pneumococcal meningitis.

Oxidative stress, cytokine/chemokine and disruption of blood-brain barrier in neonate rats after meningitis by Streptococcus agalactiae.

We verify the levels of cytokine/chemokine, myeloperoxidase activity, oxidative stress and disruption of BBB in hippocampus and cortex of the neonate Wistar rats after meningitis by S. agalactiae. In the hippocampus the levels were increased of CINC-1 at 6 h and 12 h, IL-1ß at 6, 12 and 24 h, IL-6 at 6, 24 and 96 h, IL-10 at 24, 48 and 96 h and TNF-α at 24 h and 96 h. In the cortex the CINC-1 and IL-1ß levels were found increased at 6 h. The MPO activity was significantly elevated at 24, 48 and 98 h in hippocampus and at 6, 12, 24, 48 and 96 h in the cortex. The breakdown of BBB started at 12 h.TBARS levels were elevated in the hippocampus at 6, 12, 24, 48, 72 and 96 h and cortex at 72 and 96 h. Protein carbonyls were elevated in the hippocampus and cortex at 6, 24, 48, 72 and 96 h. There was a decrease of SOD activity in hippocampus and in cortex. Catalase activity was elevated in hippocampus at 6 h and in the cortex at 12 and 96 h. Neonatal bacterial infections of the CNS are severe, the interference with the complex network of cytokines/chemokine, other inflammatory mediators and oxidants tend to aggravate the illness and can be involved in the breakdown of the BBB.

Maternal deprivation induces depressive-like behaviour and alters neurotrophin levels in the rat brain.

The present study was aimed to evaluate the behavioral and molecular effects of maternal deprivation in adult rats. To this aim, male rats deprived and non-deprived were assessed in the forced swimming and open-field tests in adult phase. In addition adrenocorticotrophin hormone (ACTH) levels was assessed in serum and brain-derived-neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and nerve growth factor (NGF) protein levels were assessed in prefrontal cortex, hippocampus and amygdala. We observed that maternal deprivation increased immobility time, and decreased climbing time, without affecting locomotor activity. ACTH circulating levels were increased in maternal deprived rats. Additionally, BDNF protein levels were reduced in the amygdala and NT-3 and NGF were reduced in both hippocampus and amygdala in maternal deprived rats, compared to control group. In conclusion, our results support the idea that behavioral, ACTH circulating levels and neurotrophins levels altered in maternal deprivation model could contribute to stress-related diseases, such as depression.

Central nervous system involvement in the animal model of myodystrophy.

Congenital muscular dystrophies present mutated gene in the LARGE mice model and it is characterized by an abnormal glycosylation of α-dystroglycan (α-DG), strongly implicated as having a causative role in the development of central nervous system abnormalities such as cognitive impairment seen in patients. However, the pathophysiology of the brain involvement remains unclear. Therefore, the objective of this study is to evaluate the oxidative damage and energetic metabolism in the brain tissue as well as cognitive involvement in the LARGE((myd)) mice model of muscular dystrophy. With this aim, we used adult homozygous, heterozygous, and wild-type mice that were divided into two groups: behavior and biochemical analyses. In summary, it was observed that homozygous mice presented impairment to the habituation and avoidance memory tasks; low levels of brain-derived neurotrophic factor (BDNF) in the prefrontal cortex, hippocampus, cortex and cerebellum; increased lipid peroxidation in the prefrontal cortex, hippocampus, striatum, and cerebellum; an increase of protein peroxidation in the prefrontal cortex, hippocampus, striatum, cerebellum, and cortex; a decrease of complex I activity in the prefrontal cortex and cerebellum; a decrease of complex II activity in the prefrontal cortex and cerebellum; a decrease of complex IV activity in the prefrontal cortex and cerebellum; an increase in the cortex; and an increase of creatine kinase activity in the striatum and cerebellum. This study shows the first evidence that abnormal glycosylation of α-DG may be affecting BDNF levels, oxidative particles, and energetic metabolism thus contributing to the memory storage and restoring process.

Chronic exposure to cigarette smoke during gestation results in altered cholinesterase enzyme activity and behavioral deficits in adult rat offspring: potential relevance to schizophrenia.

Prenatal cigarette smoke exposure (PCSE) has been associated with physiological and developmental changes that may be related to an increased risk for childhood and adult neuropsychiatric diseases. The present study investigated locomotor activity and cholinesterase enzyme activity in rats, following PCSE and/or ketamine treatment in adulthood. Pregnant female Wistar rats were exposed to 12 commercially filtered cigarettes per day for a period of 28 days. We evaluated motor activity and cholinesterase activity in the brain and serum of adult male offspring that were administered acute subanesthetic doses of ketamine (5, 15 and 25 mg/kg), which serves as an animal model of schizophrenia. To determine locomotor activity, we used the open field test. Cholinesterase activity was assessed by hydrolysis monitored spectrophotometrically. Our results show that both PCSE and ketamine treatment in the adult offspring induced increase of locomotor activity. Additionally, it was observed increase of acetylcholinesterase and butyrylcholinesterase activity in the brain and serum, respectively. We demonstrated that animals exposed to cigarettes in the prenatal period had increased the risk for psychotic symptoms in adulthood. This also occurs in a dose-dependent manner. These changes provoke molecular events that are not completely understood and may result in abnormal behavioral responses found in neuropsychiatric disorders, such as schizophrenia.

Lamotrigine treatment reverses depressive-like behavior and alters BDNF levels in the brains of maternally deprived adult rats.

Lamotrigine is an anticonvulsant and has an antiglutamatergic action, which may contribute to its antidepressant effects, since glutamate has been linked to depression. The purpose of the present study was to investigate the behavioral and molecular effects of lamotrigine treatment in maternally deprived rats. To this aim, deprived and non-deprived male rats were treated with lamotrigine (20 mg/kg) once a day for 14 days during their adult phase. Their behavior was then assessed in the forced swimming and open field tests. In addition to this, the BDNF and NGF levels were assessed in the prefrontal cortex, hippocampus and amygdala. In the course of this study we demonstrated that maternally deprived rats treated with saline and lamotrigine showed an increase in their immobility time and a decrease in the climbing and swimming times when compared with non-deprived rats treated with saline alone. Treatment with lamotrigine reversed the increase in the immobility time in the deprived rats. The BDNF levels were decreased in the amygdala in deprived rats treated with saline, and treatment with lamotrigine reversed this decrease. The NGF levels were decreased in the hippocampus in deprived rats treated with saline, but treatment with lamotrigine did not reverse this decrease. In conclusion, lamotrigine showed antidepressant effects in the forced swimming test, and it presented positive effects on the BDNF protein levels in the amygdala of maternally deprived rats.

A kinetic study of the cytokine/chemokines levels and disruption of blood-brain barrier in infant rats after pneumococcal meningitis.

Bacterial meningitis is an inflammation of the meninges and subarachnoid space that occurs in response of bacteria. Young children are particularly vulnerable to bacterial meningitis, two thirds of meningitis deaths in low-income countries occur among children under the age of fifteen. The main bacterial pathogens causing meningitis beyond the neonatal period are Streptococcus pneumoniae, Haemophilus influenza type b and Neisseria meningitidis. Therefore, the aim of this study is to evaluate the kinetic and the levels of TNF-α, IL-1ß, IL-6, IL-10 and CINC-1 in different brain regions as well as the blood-brain barrier permeability after meningitis induced by S. pneumoniae in infant Wistar rats. The animals underwent a magna cistern tap receiving either 10µL sterile saline as a placebo or an equivalent volume of a S. pneumoniae suspension at the concentration 1×10(6)CFU/mL. The animals were killed at different times after induction. The brain was removed and the hippocampus and the cortex were isolated and used for the determination of cytokine/chemokine levels and blood-brain barrier permeability. The cerebrospinal fluid was obtained by puncture of the cisterna magna to TNF-α and IL-1ß analysis. In the hippocampus, the CINC-1 and IL-1ß levels were found increased at 6h, 12h and 24h after pneumococcal meningitis induction. In the cortex the levels of the CINC-1 were increased at 6h, 12h and 24h. The IL-1ß and TNF-α were increased at 12h and 24h. The level of IL-6 was increased only after 24h after pneumococcal meningitis induction. In cerebrospinal fluid, the TNF-α was increased at 12h, 24h and IL-1 was increased at 24h after S. pneumoniae induction. The blood-brain barrier breakdown in hippocampus and cortex were observed at 12h until 24h during meningitis. In conclusion, a peak of pro-inflammatory cytokine/chemokine is associated with disruption of the blood-brain barrier in infants with pneumococcal meningitis.

Dexamethasone treatment reverses cognitive impairment but increases brain oxidative stress in rats submitted to pneumococcal meningitis.

Pneumococcal meningitis is associated with a significant mortality rate and neurologic sequelae. The animals received either 10 µL of saline or a S. pneumoniae suspension and were randomized into different groups: sham: placebo with dexamethasone 0.7 mg/kg/1 day; placebo with dexamethasone 0.2 mg/kg/7 days; meningitis groups: dexamethasone 0.7 mg/kg/1 day and dexamethasone 0.2 mg/kg/7 days. Ten days after induction we evaluated memory and oxidative stress parameters in hippocampus and cortex. In the step-down inhibitory avoidance task, we observed memory impairment in the meningitis group with dexamethasone 0.2 mg/kg/7 days. The lipid peroxidation was increased in hippocampus in the meningitis groups with dexamethasone and in cortex only in the meningitis group with dexamethasone 0.2 mg/kg/7 days. The protein carbonyl was increased in hippocampus in the meningitis groups with dexamethasone and in cortex in the meningitis groups with and without dexamethasone. There was a decrease in the proteins integrity in hippocampus in all groups receiving treatment with dexamethasone and in cortex in all groups with dexamethasone (0.7 mg/kg/1 day). The mitochondrial superoxide was increased in the hippocampus and cortex in the meningitis group with dexamethasone 0.2 mg/kg/7 days. Our findings demonstrate that dexamethasone reverted cognitive impairment but increased brain oxidative stress in hippocampus and cortex in Wistar rats ten days after pneumococcal meningitis induction.

Prenatal exposure to cigarette smoke causes persistent changes in the oxidative balance and in DNA structural integrity in rats submitted to the animal model of schizophrenia.

Epidemiological studies have indicated that prenatal exposure to environmental insults can bring an increased risk of schizophrenia. The objective of our study was to determine biochemical parameters in rats exposed to cigarette smoke (CS) in the prenatal period, evaluated in adult offspring submitted to animal model of schizophrenia induced by acute subanaesthetic doses of ketamine (5 mg/kg, 15 mg/kg and 25 mg/kg). Pregnant female Wistar rats were exposed to 12 commercially filtered cigarettes per day, daily for a period of 28 days. We evaluated the oxidative damage in lipid and protein in the rat brain, and DNA damage in the peripheral blood of male adult offspring rats. To determine oxidative damage in the lipids, we measured the formation of thiobarbituric acid reactive species (TBARS) and the oxidative damage to the proteins was assessed by the determination of carbonyl groups content. We also evaluated DNA damage using single-cell gel electrophoresis (comet assay). Our results showed that rats exposed to CS in the prenatal period presented a significant increase of the lipid peroxidation, protein oxidation and DNA damage in adult age. We can observe that the animals submitted at acute doses of ketamine also presented an increase of the lipid peroxidation and protein oxidation at different doses and structures. Finally, we suggest that exposure to CS during the prenatal period affects two essential cerebral processes during development: redox regulation and DNA integrity, evaluated in adult offspring. These effects can leads to several neurochemical changes similar to the pathophysiology of schizophrenia.

Correlation between behavioral deficits and decreased brain-derived neurotrophic [correction of neurotrofic] factor in neonatal meningitis.

We investigated the correlation between memory impairment and hippocampal brain-derived neurotrophic factor (BDNF) levels in adult rats submitted to experimental meningitis (Streptococcus pneumoniae) in the neonatal period. Sixty days after inoculation the animals were submitted to the behavior tasks and hippocampal BDNF protein were evaluated. In the meningitis group, there was impairment in habituation and avoidance memory and a decrease in the BDNF levels. The decrease in hippocampal BDNF levels correlated to impairment in memory in adult animals submitted to experimental meningitis in the neonatal period.