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E A Cavalheiro

Publications and source records attributed to E A Cavalheiro.

At least 55 records · Page 3Linked to original sources
PubMed1997

Neuropeptide-Y immunoreactivity in the pilocarpine model of temporal lobe epilepsy.

Neuropeptide-Y (NPY) is expressed by granule cells and mossy fibres of the hippocampal dentate gyrus during experimental temporal lobe epilepsy (TLE). This expression may represent an endogenous damping mechanism since NPY has been shown to block seizure-like events following high-frequency stimulation in hippocampal slices. The pilocarpine (PILO) model of epilepsy is characterized by an acute period of status epilepticus followed by spontaneous recurrent seizures and related brain damage. We report peroxidase-antiperoxidase immunostaining for NPY in several brain regions in this model. PILO-injected animals exhibited NPY immunoreactivity in the region of the mossy fibre terminals, in the dentate gyrus inner molecular layer and, in a few cases, within presumed granule cells. NPY immunoreactivity was also dramatically changed in the entorhinal cortex, amygdala and sensorimotor areas. In addition, PILO injected animals exhibited a reduction in the number of NPY-immunoreactive interneurons compared with controls. The results demonstrate that changes in NPY expression, including expression in the granule cells and mossy fibres and the loss of vulnerable NPY neurons, are present in the PILO model of TLE. However, the significance of this changed synthesis of NPY remains to be determined.

Animals↗
PubMed1997

Blockade of spreading depression in chronic epileptic rats: reversion by diazepam.

Following pilocarpine-induced status epilepticus, rats become chronically epileptic showing 2-3 spontaneous recurrent seizures per week. The aim of this work was to verify the characteristics of spreading depression (SD) in these chronic epileptic rats (n = 16). SD was evoked in one point of the frontal cortex by topical application of KCl solution at 20 min intervals, and recordings were made in two points over the parietal cortex (a 'near' point and a 'remote' one, about 3 and 8 mm posterior to the stimulating region, respectively). In all control animals (n = 10), KCl stimulation elicited SD which in 100% of the cases propagated regularly to the two recording points. In the chronic epileptic rats only about 50% of the KCl applications were effective in eliciting SD, detected at the 'near' recording point. Of these, only 3% propagated to the 'remote' recording point. In eight of the above epileptic rats, diazepam (5-10 mg/kg, i.v.) was injected after 1-2 h of recording, when SD incidence in response to KCl stimulation has been established. After diazepam, the incidence of SDs propagating regularly to the 'near' and to the 'remote' recording points increased significantly, (132 and 53 SDs, respectively, out of 139 KCl stimulations), as compared with the incidence in the pretreatment period (33 and 1, respectively, out of 63 stimulations; P < 0.005). These data indicate an impairment in the susceptibility to cortical SD in chronic epileptic rats suggesting modifications in cortical excitability in the pilocarpine model of epilepsy. They also indicate a facilitatory effect of diazepam on SD, confirming previous observations in non-epileptic rats.

Animals↗
PubMed1996

Disruption of light-induced c-Fos immunoreactivity in the suprachiasmatic nuclei of chronic epileptic rats.

Photic stimulation during specific day periods may induce Fos oncoprotein expression within the ventrolateral part of the suprachiasmatic nucleus (SCN) in the hypothalamus of rodents. This phenomenon appears to be a major molecular mechanism for environmental light/dark cycle entrainment of the mammalian circadian clock. Light-dependent synchronization of circadian rhythmicity may be disrupted in epilepsy, a chronic neurological disorder often associated with chronobiological features such as seizure periodicity and disruption of endogenous biological rhythms. The present work examined the light-induced Fos protein expression on the SCN in the pilocarpine model of chronic epilepsy. Fos-like immunoreactivity was significantly reduced in the SCN of chronic epileptic rats after photic stimulation during the subjective night. These results indicate an altered Fos protein expression in the SCN of chronic epileptic rats. The present findings reveal that pathological neural events underlying epileptogenesis may disturb circadian rhythm regulation. The experimental study of circadian clock activity in the SCN may clarify the molecular bases of chronobiological disturbances in epilepsy.

Animals↗
PubMed1996

Lack of Fos-like immunoreactivity after spontaneous seizures or reinduction of status epilepticus by pilocarpine in rats.

Acute seizures and status epilepticus induced by pilocarpine lead to the expression of Fos-like immunoreactivity in several specific brain areas in a manner similar to that of other models of limbic seizures. Upon development of status epilepticus after systemic pilocarpine injection, animals develop a state where chronic spontaneous seizures recur. Assessment of Fos-like immunoreactivity after such spontaneous seizures or after status epilepticus reinduction reveals either lack of staining or a weak reaction in a few brain areas including the ventral tip of the dentate gyrus, prepiriform, lateral piriform and perirhinal cortices, and scattered locations throughout temporal neocortex. Our results suggest that status epilepticus induction may lead to a long-lasting state of Fos down-regulation.

Animals↗
PubMed1996

Branched connections to the septum and to the entorhinal cortex from the hippocampus, amygdala, and diencephalon in the rat.

Neuronal cell populations giving origin to bifurcating projections to the septum and the entorhinal cortex were studied in the rat by means of double retrograde labeling using the fluorescent tracers Fast Blue and Diamidino Yellow. Double labeled pyramidal neurons were consistently detected in the temporal level of the CA1 area and subiculum of the hippocampal formation, where they represented at least 50% of the cells retrogradely labeled from the entorhinal injections. Double labeled neurons were also detected in the amygdala, where they prevailed in the basal complex. Scattered double labeled neurons were observed in a number of hypothalamic nuclei, with a slight predominance in the preoptic region. Finally, a few double labeled cells were detected in the midline thalamus, and especially in the thalamic paraventricular nucleus. In all these structures, double labeled neurons were located ispilaterally to the injection sites. The present data indicate that the septum and entorhinal cortex are tightly interconnected by axonal bifurcations deriving from a variety of telencephalic and diencephalic sources.

Amygdala↗
PubMed1996

Monoamines and their metabolites in cerebrospinal fluid and temporal cortex of epileptic patients.

The involvement of monoamines in the initiation or maintenance of epileptic phenomena has been extensively studied in cerebral tissues and in cerebrospinal fluid. The present work was undertaken to study monoamines and their metabolites in human spiking and non-spiking temporal cortex excised from patients with complex partial seizures unresponsive to available anticonvulsants. The same substances were also analyzed by HPLC-ED in cerebrospinal fluid obtained 24 h before the surgical procedure and compared with those from patients with chronic headache and normal neurological evaluation. The results show increased 5-HT, 5-HIAA and HVA levels in spiking compared with non-spiking cortex. Cerebrospinal fluid levels of 5-HIAA and HVA are concomitantly increased in epileptic compared with headache patients.

Adult↗
PubMed1996

Developmental aspects of the pilocarpine model of epilepsy.

Prolonged seizures in young children may precede the later development of focal or generalized seizures. To study the age-related susceptibility to the development of chronic epilepsy we used the pilocarpine model of epilepsy (PME). This model is well characterized in adult rats, and presents three distinct periods: (a) an acute period of status epilepticus (SE), (b) a silent period of a progressive normalization of EEG and behavior, (c) a chronic period of spontaneous recurrent seizures. Wistar rats aged 7-120 days received pilocarpine hydrochloride (170-380 mg/kg, i.p., according to age), 30 min after methylscopolamine (1 mg/kg, s.c.). All surviving animals were observed for 120 days. The results indicate that chronic seizures following pilocarpine-induced status epilepticus can be induced in rats if the status is induced after the 18th day of life. The age-related differences in the susceptibility of young rats to developed chronic epilepsy reflect the complexity of seizure activity in immature brain and provide for an apparent distinction between the mechanisms of epileptogenesis in the mature and developing nervous system.

Age Factors↗
PubMed1996

The pilocarpine model of epilepsy in mice.

PURPOSE: To characterize the acute and chronic behavioral, electrographic and histologic effects of sustained seizures induced by pilocarpine in mice. METHODS: After status epilepticus, the surviving animals were continuously monitored for 24 h/day for < or = 120 days. The brains were processed by using neo-Timm and Nissl stains. RESULTS: The first spontaneous seizures occurred between 4 and 42 days after status epilepticus. The mean "seizure-silent period" lasted for 14.4 +/- 11.9 days. During the chronic phase, recurrent spontaneous seizures were observed 1-5 times per animal per week and were associated with sprouting in the supragranular layer of the dentate gyrus. CONCLUSIONS: Structural brain damage promoted by pilocarpine-induced status epilepticus may underlie or be associated with recurrent spontaneous seizures in mice.

Animals↗
PubMed1996

Effect of an aerobic exercise program on blood pressure and catecholamines in normotensive and hypertensive subjects.

Interrelations between physical exercise, monoamines and hypertension are postulated by various investigators. The purpose of the present study was to determine and compare catecholamine levels at rest and after a 12-week aerobic exercise program in 11 sedentary normotensive (N) and 8 hypertensive (H) men. Plasma catecholamines were determined by high performance liquid chromatography with electrochemical detection. A significant post-exercise increase in plasma noradrenaline was observed in the N and H groups (P < 0.01) both before and after the aerobic exercise program. The hypertensive group showed a significant reduction of the sum of 7 skinfold thickness scores after the aerobic exercise program (from 178.7 +/- 65.6 to 144.0 +/- 47.4 mm) although no significant difference was observed when the body mass index was compared. A significant reduction in diastolic blood pressure at rest was observed in the H group after the aerobic exercise program (from 99.2 +/- 2.0 to 85.0 +/- 5.5). There were no significant differences in catecholamine concentrations between groups before and after the 12-week aerobic exercise program at rest and post-exercise. These data show a relationship between physical exercise and hypertension that was not related to changes in plasma catecholamine levels.

Adult↗
PubMed1995

Suppression of pilocarpine-induced status epilepticus and the late development of epilepsy in rats.

Status epilepticus (SE) has been related to subsequent development of epilepsy. The present work was aimed at elucidating the relationship between the duration of pilocarpine- (PILO)-induced SE and the subsequent development of epilepsy in rats. The latency for the appearance of the first spontaneous seizure, the frequency of spontaneous seizures, the cell density in the hippocampal formation and the density of supragranular neo-Timm staining were monitored. At 30 min, 1, 2 and 6 h after the beginning of SE, animals were treated with diazepam plus pentobarbital. In non-treated rats, SE remitted spontaneously. Animals exhibiting 30 min of PILO-induced SE did not develop spontaneous seizures. Hippocampal cell counts and the density of neo-Timm staining in these animals were similar to those observed in control rats. In the other groups longer SE durations were related to: shorter latency for the appearance of the first spontaneous seizure, increased number of the spontaneous recurrent seizures, severe cell loss in the hippocampal formation, or increased supragranular neo-Timm staining. These data suggest that more than 30 min of SE is required to produce hippocampal damage with subsequent synaptic reorganization of the mossy fibre pathway that could account for SRSs observed in the PILO model of epilepsy.

Animals↗
PubMed1995

Profile of prostaglandin levels in the rat hippocampus in pilocarpine model of epilepsy.

Pilocarpine (PILO) administered to rats acutely induces status epilepticus (acute period), which is followed by a transient seizure-free period (silent period), and finally by a chronic phase of spontaneous recurrent seizures (chronic period, SRS) that lasts for the rest of animal's life. Hippocampal neurochemical changes following PILO administration include alteration in monoamines and amino acids content during all phases of this epilepsy model. The present work was delineated to study the content of prostaglandins (PG) levels in hippocampus during the three phases of this model. The levels of PG E2, PG F2 alpha and PG D2 were measured by radioimmunoassay 1 h after PILO, 5 h after PILO, during the silent period, and interictally into the chronic period. The results show, in hippocampus of rats, increase of PG F2 alpha and PG D2 during status epilepticus, increase of PG D2 during the silent period and increase of PG E2 and PG D2 during the chronic phase, when compared with control group. These changes match previously reported alteration in monoamines and amino acid levels, showing that altered neurotransmission is accompanied by changes in second messengers and enzyme activity related to PG production during all phases of the epilepsy model.

Animals↗
PubMed1995

Effects of conventional antiepileptic drugs in a model of spontaneous recurrent seizures in rats.

Pilocarpine (PILO) induces in rats limbic seizures that become secondarily generalized and evolve to status epilepticus (SE). Spontaneous recurrent seizures are registered during the long-term period following the systemic administration of PILO in rats. EEG, behavioral, and pathological features resemble those of complex partial seizures. The antiepileptic drugs (AEDs) diazepam, phenobarbital (PB), valproic acid (VPA) and trimethadione protect against PILO-induced SE while phenytoin (PHT) and carbamazepine (CBZ) are ineffective. Studies with AEDs on spontaneous seizures (chronic period) of this model have not yet been established. We now report the effects of different AEDs on spontaneous seizures. Male Wistar rats were subjected to PILO-induced SE. Following recovery from SE animals were daily observed in order to detect spontaneous seizures and to establish the baseline seizure frequency. PB 40 mg/kg, PHT 100 mg/kg, CBZ 120 mg/kg, VPA (450 mg/kg and 600 mg/kg) and ethosuximide (ETX) 400 mg/kg were given daily to epileptic rats for two weeks during the spontaneous recurrent seizures period. PB, CBZ and PHT were effective against spontaneous seizures. VPA was also effective against spontaneous seizures at the dose of 600 mg/kg and ETX was inactive against these seizures. Such pharmacological profiles correlate well with complex partial seizures. The results indicate that spontaneous recurrent seizures after PILO-induced SE may be a useful model for finding new AEDs with better efficacy against complex partial seizures. The use of animal models that share both pharmacological and phenomenological features with human epilepsy might improve their predictive value for specific types of human epilepsy.

Animals↗
PubMed1994

Increased serotonin levels in physically trained men.

It has been postulated that exercise training influences monoaminergic systems. The purpose of the present study was to determine the basal level of serum serotonin (5HT) in track and field-trained men (N = 15) and in untrained subjects matched by age, weight and height (N = 15). Serum serotonin levels were determined in blood drawn into dry tubes after a 12-h fast by high performance liquid chromatography utilizing electrochemical detection. Mean (+/- SD) serum serotonin levels were: 141.32 +/- 38.77 ng/ml for trained subjects and 97.77 +/- 30.53 ng/ml for untrained subjects (P < 0.01, Student t-test). These data show that basal serum serotonin levels are increased by exercise training.

Adult↗
PubMed1993

Epilepsy and hormonal regulation: the patterns of GnRH and galanin immunoreactivity in the hypothalamus of epileptic female rats.

Endocrine and reproductive alterations are frequently reported to occur in women with temporal lobe epilepsy as well as in female rats in different experimental models of limbic seizures. We have recently observed that rats with structural damage of limbic structures induced by sustained convulsions triggered by systemic administration of pilocarpine develop spontaneous seizures after a mean latency of 15 days. In order to investigate the possible substrate of endocrine alterations in epilepsy, changes of the gonadotropin-releasing hormone (GnRH) and the neuropeptide galanin (GAL) were studied in the hypothalamus of epileptic female rats after pilocarpine treatment. Female rats injected with pilocarpine (320-350 mg/kg, i.p.) and control cases injected with saline were killed 10-20 h, 10-15 or 60-90 days following treatment. In some of these animals colchicine was injected in the lateral cerebral ventricle 24 h before death. GnRH immunopositivity was observed in the hypothalamus in neuronal cell bodies, fibers and punctate elements of both epileptic and control cases. A striking reduction of the density of GnRH-immunoreactive fibers and puncta was observed in the hypothalamus of the epileptic female rats killed 10-15 or 60-90 days following pilocarpine administration. No significant differences were observed in the number and size of GAL-immunoreactive perikarya of epileptic and control cases. The present findings suggest that a substantial rearrangement of GnRH-containing efferents, and in particular a loss of their terminal branches, occurs in the epileptic rat brain. Comparable regressive changes could account for alterations in endocrine and reproductive functions observed in temporal lobe epilepsy.

Animals↗
PubMed1993

Serum serotonin levels of normal and autistic children.

1. Serum serotonin (5HT) was determined in normal and autistic children by high performance liquid chromatography with electrochemical detection (HPLC-ED), after serum deproteinization. 2. The sample deproteinization was carried out by the addition of 3.4 M HCLO4 to a small volume of the serum, followed by freezing, centrifugation, dilution and injection of sample into the HPLC. 3. Serum 5HT concentration was significantly increased in autistic children (303 +/- 92 ng/ml) (N = 19) when compared to that of normal children (215 +/- 67 ng/ml) (N = 46). The data of normal children analyzed by ANOVA for sex or age showed no difference. 4. The method employed in this study showed high resolution, good sensitivity and can be used for routine determination of serum 5HT in the clinical investigation of hyperserotonemia in autism.

Analysis of Variance↗
PubMed1992

Age dependency of the susceptibility of rats to aminooxyacetic acid seizures.

Immature rats are more susceptible to clonic seizures induced by aminooxyacetic acid (AOAA) than mature and senile rats. Highest susceptibility to AOAA seizures was observed in 7-14-day-old rat pups. The lowest susceptibility was recorded in 10-20 month-old rats. AOAA seizures in 14-day-old rats were blocked by clonazepam and valproate, but not by phenobarbital, carbamazepine, diphenylhydantoin, trimethadione or ethosuximide. Morphological analysis of brains from 14-day- and 3-month-old rats which experienced AOAA seizures did not reveal epilepsy-related damage. These observations suggest that immature rat brain is highly prone to convulsions induced by AOAA and that such convulsions are difficult to control by available antiepileptic treatment.

Aging↗