The effect of vitamin E supplementation on brain tissue element levels in epileptic rats.

The aim of this study was to investigate how the application of vitamin E affected the levels of chemical elements in the brain tissues of epilepsy-induced rats. The sample of 40 adult male rats was separated into 4 equal groups: Group 1: control, Group 2: vitamin E; Group 3: penicillin to promote epileptic form activity and Group 4: penicillin + vitamin E. After three months of treatment, an Atomic Absorption Spectrophotometer was used to analyze the presence of the elements in brain tissue sections (brain, brainstem, cerebellum) of the decapitated animals. The levels of magnesium in the groups that received vitamin E (G2 and 4) were significantly higher than in the control group (G1) and the first epilepsy group (G3) (p.05).Chrome and zinc levels in brain, brainstem, and cerebellum tissue of the two epilepsy groups (G3-4) decreased significantly compared to the control group (G1) and the vitamin E group (G2) (p.05). The levels of copper in the brainstem and lead in the cerebellum of the first epilepsy group (G3) were higher than in all other groups (p.05). The findings showed that the application of vitamin E in experimental epilepsy may have a limited effect on element metabolism in brain tissue. A decline in zinc levels in the brain, brainstem and cerebellum tissues in epilepsy groups constitutes another result of our study. This should be examined further to determine whether decreased levels of zinc play a role in epilepsy pathogenesis.

Hemopressin increases penicillin-induced epileptiform activity in rats.

OBJECTIVE: Hemopressin (Hp) is the first peptide ligand described for the CB1 cannabinoid receptor. Therefore, we aimed to investigate the effect of hemopressin on pencillin-induced epileptiform activity by using electrophysiological recording (ECoG) technique. METHODS: Male Wistar rats were anesthetized with urethane (1.25 g/kg), and epileptiform activity was induced by intracortical injection of penicillin (500 IU). Animals were randomly divided into eight groups. Subsequently, the rats were administered with saline or hemopressin as follows: saline control group (Group I: 2 µl/i.c.v/saline), hemopressin groups (Group II: 0.025 µg/i.c.v; Group III: 0.075 µg/i.c.v; Group IV: 0.15 µg/i.c.v; Group V: 0.3 µg/i.c.v; Group VI: 0.6 µg/i.c.v; Group VII: 1.2 µg/i.c.v; Group VIII: 2.4 µg/i.c.v). The various doses of hemopressin were injected intracerebroventricularly (i.c.v) 30 minutes after penicillin (2.5µl) injection. After hemopressin injection, ECoGs were recorded for three hours. RESULTS: Hp at doses of 0.075, 0.15, 0.3, 0.6, 1.2 and 2.4 µg/kg significantly increased the frequency of epileptiform ECoG activity compared to penicillin-injected group without changing the amplitude. The 0.6 µg hemopressin was the most effective dose to increase the epileptiform activity (p 0.05). CONCLUSIONS: The results of this study provided electrophysiological evidence for hemopressin to be modulating penicillin-induced epileptiform activity by acting as CB1 receptor antagonist. Further studies are required to elucidate the involved mechanism underlying this effect (Fig. 3, Ref. 40).

The role of cannabinoids and leptin in neurological diseases.

Cannabinoids exert a neuroprotective influence on some neurological diseases, including Alzheimer's, Parkinson's, Huntington's, multiple sclerosis and epilepsy. Synthetic cannabinoid receptor agonists/antagonists or compounds can provide symptom relief or control the progression of neurological diseases. However, the molecular mechanism and the effectiveness of these agents in controlling the progression of most of these diseases remain unclear. Cannabinoids may exert effects via a number of mechanisms and interactions with neurotransmitters, neurotropic factors and neuropeptides. Leptin is a peptide hormone involved in the regulation of food intake and energy balance via its actions on specific hypothalamic nuclei. Leptin receptors are widely expressed throughout the brain, especially in the hippocampus, basal ganglia, cortex and cerebellum. Leptin has also shown neuroprotective properties in a number of neurological disorders, such as Parkinson's and Alzheimer's. Therefore, cannabinoid and leptin hold therapeutic potential for neurological diseases. Further elucidation of the molecular mechanisms underlying the effects on these agents may lead to the development of new therapeutic strategies for the treatment of neurological disorders.

Programa de incentivo de la actividad física apoyado con contadores de pasos en la enfermedad pulmonar obstructiva crónica / A program of physical activity enhancement using pedometers in chronic obstructive pulmonary disease

Introducción: La actividad física diaria está reducida en la EPOC lo que se asocia a una mayor morbimortalidad. La indicación médica de caminar más se ha demostrado poco eficaz y, en nuestro medio, se desconoce el beneficio del uso de los contadores de pasos en la EPOC. Objetivo: Determinar el efecto de los contadores de pasos para incentivar la actividadfísica en la EPOC. Método: 55 Pacientes con EPOC fueron incorporados a un programa de tres meses destinado a aumentar su actividad física y fueron asignados aleatoriamente a dos grupos: en uno el paciente autocontroló su actividad con un contador de pasos (grupo experimental) y en el otro se siguió el manejo habitual (grupo control). Al comienzo y al final del estudio se realizaron las siguientes mediciones: promedio de pasos caminados por día medidos en una semana, espirometría, caminata de seis minutos (C6M), disnea con escala de la Medical Research Council Modificada (mMRC) y calidad de vida mediante cuestionario de Saint George (SGRQ) y COPD Assessment Test (CAT). Resultados: 69 por ciento de los pacientes eran hombres, edad promedio 68 años, VEF1ICVF = 55 por ciento, VEF(1)63 por ciento predicho. El grupo experimental (n = 29) y el control (n = 26) presentaron características basales comparables. El grupo experimental presentó una diferencia significativa en el incremento de los pasos por día en comparación con el grupo control (mediana de 2073,5 versus -68, p < 0,001). También hubo diferencia en la reducción del componente síntomas del SGRQ (promedio de -9,65 versus 0,05 puntos, grupo experimental versus control, p = 0,048). Conclusión: Un programa de incentivo de la actividad física apoyado con contadores de pasos es útil para incentivar la actividad física en la EPOC.

Introduction: The level of daily physical activity is reduced in COPD and has a negative effect on the morbidity and mortality of this condition. Usual advice is not sufficient to reverse the sedentary condition. Pedometers are widely used but their effects in COPD have not been tested in our country. Aim: To determine the effect of pedometers on physical activity in COPD patients. Method: 55 COPD patients were recruited for a 3 months individual program promoting daily physical activity enhancement and were randomly assigned either to a pedometer-based program (experimental group) or to usual care (control group). At the beginning and at the end of the intervention period we measured the average daily steps over one week, exercise capacity using the six-minute walking test (6MWT), the MMRC dyspnoea score, the Saint George Respiratory Questionnaire (SGRQ) and the COPD assessment Test (CAT) to estimate quality of life. Results: 69% of the subjects were male, mean age 68 years, mean FEV1IFVC 55%, mean FEV163% of predicted value. Experimental (n = 29) and control group (n = 26) had comparable baseline characteristics. There was a significant difference in the increase of steps/day in the experimental group in comparison with the control group (median value = 2073.5 versus -68, p < 0.001). Also, a significant difference was observed in the symptoms subscale score of the SGRQ (reduction of 9.65 versus 0.05points, experimental versus control group, p = 0.048). Conclusions: Pedometers are a useful tool to increase physical activity level in COPD.

A simplified application of systematic field sampling and low-cost video recording set-up for viewing disector pairs - exemplified in the rat cochlear nucleus.

A description of a simple and efficient way of systematic field sampling along with a low-cost set-up for simultaneous viewing of physical disector pairs at the light microscopic level is presented. So far the use of a programmable motorized stage for the former purpose and two projection microscopes for the latter have proved to be the most efficient and fastest solutions, but the relatively high expense of purchasing such equipment constitutes a major impediment to the widespread use of such stereological methods. We describe practical applications of two new cost-effective alternative approaches derived from existing ones. These approaches are used in estimating the total number of neurones in the cochlear nucleus of the rat and involve the systematic selection of section fields at a magnification significantly lower than the magnification used for counting and a video recording set-up for comparing section pairs. Apart from providing a cheap way for the implementation of the physical disector, the main feature of the application, which may also encourage its use, is that it provides an efficient and simple design for systematic area sampling without requiring any specialized equipment. The same is true for optical disector designs, where the procedure is simplified even further.

The effects of albendazole solution at scolocidal concentration in the rat brain.

Intra-operative cyst rupture is a catastrophic event in the intracranial hydatid cyst disease. Dissemination of the cyst contents may lead to severe anaphylactic reactions and an increased risk of recurrence. Several scolicidal agents have been used to eradicate the infective scolices but recurrences occur and no solution has been evaluated for its adverse effects to the brain tissue. Being a specific scolocidal agent albendazole has been shown to be 100% scolicidal in vitro. In this study, we present the electrophysiological and histopathological effects of intracerebral 2% albendazole injection in the rat brain. Vascular, neuronal and glial as well as inflammatory changes were evaluated in order to detect any adverse pharmacological effects. Electrophysiological and most microscopic parameters showed no significant effects attributable to albendazole but in 25% of the albendazole group cerebral gliosis was detected whereas no gliosis was present in the control group. It is concluded that being a specific scolicidal agent albendazole offers an efficient alternative for ruptured cerebral hydatid disease, but the significance and clinical importance of the gliosis should be further investigated.

Segregation of on and off bipolar cell axonal arbors in the absence of retinal ganglion cells.

Retinal cells that respond selectively to light onset or offset are segregated into On and Off pathways. Here, we describe the development of cone bipolar cells whose axonal arbors at maturity synapse onto ganglion cell dendrites confined to On and Off strata of the inner plexiform layer (IPL). In particular, we sought to determine whether the formation of this segregated pattern is dependent on the presence of ganglion cells. Developing bipolar cells were visualized using an antibody against recoverin, the calcium binding protein that labels On and Off cone bipolar cells in the adult rat retina. Recoverin-positive cells were apparent in the ventricular zone on the day of birth [postnatal day 0 (P0)], before bipolar cells begin to migrate to the inner nuclear layer. Two distinct strata were first apparent in the IPL at P8, with the Off pathway maturing earlier than the On pathway. There was no indication of exuberant bipolar cell projections. Throughout development, there were also a small number of recoverin-positive cells of unknown origin in the ganglion cell layer. To assess whether the formation of On and Off cone bipolar cell projections is dependent on the presence of ganglion cells, these target neurons were eliminated by unilateral section of the optic nerve. This was done on the day of birth, resulting in a total loss of ganglion cells 5-6 d before bipolar cell axons innervate the IPL. In retinas with optic nerve sections, On and Off cone bipolar cells were present, albeit at a lower than normal density, and the axonal arbors of these interneurons were organized into two distinct strata. This indicates that ganglion cells are not essential for the formation of segregated On and Off bipolar cell inputs. These results lend support to the hypothesis that specific ingrowth patterns of bipolar cell terminal arbors could regulate the formation of stratified retinal ganglion cell dendrites.

The effect of ethanol on lipid peroxidation and glutathione level in the brain stem of rat.

The effects of ethanol consumption on the levels of lipid peroxidation (TBARS) and reduced glutathione (GSH) in the brain stem of male rats were investigated. The rats randomly divided into eight groups: control, 10%, 25%, 35% ethanol-consuming groups and four groups given vitamin E. Brain stem GSH levels were significantly decreased by 39.74%, 61.57%, 78.23% in rats consuming 10%, 25% and 35% ethanol, respectively. The level of TBARS was increased six-fold, 12-fold and 17-fold in these groups when compared with the control group. The administration of vitamin E (100 mg/kg/day, i.p) to ethanol-consuming rats for 20 days caused a significant increase in glutathione levels and a significant decrease in lipid peroxidation.

Do cochlear nuclei contribute to auditory lateralization? A stereological evaluation of neuron numbers.

The aim of this study was to estimate the total number of cells in the subdivisions of the cochlear nucleus (CN) of the rat with unbiased stereological methods. The total number of neurons was determined in both the ventral cochlear nucleus (VCN) and the dorsal cochlear nucleus (DCN) to compare the right and left sides. The total cell numbers were 15,280 in the left VCN, 15,400 in the right VCN, 10,260 in the left DCN, and 10,860 in the right DCN. Comparison of the right and left major subdivisions of the CN of the rat showed that there was no significant difference between the right and left sides of the rat CN. This result indicates that the CNs do not contribute to auditory lateralization in the rat in regard to cell numbers.

Developmental changes in the electrophysiological properties of brain stem trigeminal neurons during pattern (barrelette) formation.

In the brain stem trigeminal nuclei of rodents there is a patterned representation of whiskers and sinus hairs. The subnucleus interpolaris (SPI) contains the largest and the most conspicuous whisker patterns (barrelettes). Although neural activity plays a role in pattern formation, little is known about the electrophysiological properties of developing barrelette neurons. Here we examined the functional state of early postnatal SPI neurons during and after the consolidation of patterns by using in vitro intracellular recording techniques. After the consolidation of barrelettes [>/= postnatal day (P)4], responses to intracellular current injection consistently reflected the activation of a number voltage-dependent conductances. Most notable was a mixed cation conductance (IH) that prevented strong hyperpolarization and a large low-threshold Ca2+ conductance, which led to Ca2+ spikes and burst firing. At the oldest ages tested (P11-P14) some cells also exhibited an outward K+ conductance (IA), which led to significant delays in action-potential firing. Between P0-3, a time when the formation of barrelettes in the brain stem is still susceptible to damage of the sensory periphery, cells responded linearly to intracellular current injection, indicating they either lacked such voltage-gated properties or weakly expressed them. At all ages tested (P0-14), SPI cells were capable of generating trains of action potentials in response to intracellular injection of depolarizing current pulses. However, during the first few days of postnatal life, spikes were shorter and longer. Additionally, spike trains rose more linearly with stimulus intensity and showed frequency accommodation at early ages. Taken together, these results indicate that the electrophysiological properties of SPI neurons change markedly during the period of barrelette consolidation. Moreover, the properties of developing SPI neurons may play a significant role in pattern formation by minimizing signal distortion and ensuring that excitatory responses from sensory periphery are accurately received and transmitted according to stimulus strength.

Functional connectivity in the rodent trigeminal pathway grown in vitro.

In explant cocultures of the rat trigeminal pathway, embryonic trigeminal ganglion cells grow their axons into peripheral cutaneous and central nervous system targets (R.S. Erzurumlu, S. Jhaveri, Target influences on the morphology of trigeminal axons, Exp. Neurol, 135 (1995) 1-16; R.S. Erzurumlu, S. Jhaveri, H. Takahashi, R.D.G. McKay, Target-derived influences on axon growth modes in explant cocultures of trigeminal neurons, Proc. Natl. Acad. Sci. USA 90 (1993) 7235-7239). In heterochronic cocultures, composed of embryonic trigeminal ganglion, embryonic whisker pad and postnatal brainstem slice, trigeminal axons develop arbors and terminal boutons in the brainstem trigeminal nuclei. To determine whether these terminal arbors establish functional connections with the brainstem neurons, we examined the electrophysiological properties of brainstem neurons and their responsiveness to trigeminal ganglion stimulation. Intracellular recordings were done in vitro on cells of the trigeminal subnucleus interpolaris (SPI) in trigeminal pathway cocultures (E15 whisker pad, E15 trigeminal ganglion, and postnatal day (PND) 0-2 brainstem slice) or in the SPI of acutely prepared brainstem slices. Electrophysiological properties of SPI cells in both preparations were virtually identical. The voltage responses of SPI neurons to intracellular current injection were highly linear suggesting they lacked a number of voltage-dependent conductances. Depolarizing current injection produced trains of action potentials with a frequency that varied with stimulus intensity. In explant cocultures, electrical activation of the trigeminal ganglion evoked EPSPs, and EPSPs coupled with IPSPs in SPI cells. Bicuculline blockade of IPSP activity resulted in long lasting EPSPs whose duration increased with membrane depolarization. These results show that brainstem trigeminal neurons can retain their functional properties in culture and establish functional connections with primary sensory afferents.

Membrane properties of mouse dorsal cochlear nucleus neurons in vitro.

Intracellular recordings were made from neurons of the mouse dorsal cochlear nucleus (DCN) in vitro using current clamp techniques in the presence or absence of different ion channel blocking drugs. Four electrophysiologically distinct cell groups were identified in the DCN. The groups were characterized on the basis of their spontaneous firing properties, the shape of the action potential (AP) and the pattern of firing, the shape of the current-voltage (I/V) relationship and the effects of channel blocking agents. By comparison with known histology, three of the four DCN groups were postulated to be cartwheel-like, fusiform-like, or tuberculoventral-like cells. The fourth group was postulated to be a stellate-like as it had similar properties to the spike train (stellate) cell of the AVCN. DCN stellate-like cells were spontaneously active, the action potentials (APs) were always followed by a large, brief hyperpolarization and the cells had linear current voltage relationships. The fusiform-like cells were spontaneously active and spontaneous IPSPs were also observed. The I/V relationship was linear for these cells. Tuberculoventral-like cells were not spontaneously active, but APs could be elicited by inward current injection. The I/V relationships for tuberculoventral-like cells were linear. Cartwheel-like cells were spontaneously active. These cells were characterized by the distinctive shape of their APs which were single, large amplitude, short duration APs sometimes followed by a series of complexes consisting of small, long duration APs. Cartwheel-like cells were the only cell type in the DCN which had non-linear I/V relationships. All cells in the DCN had APs which were abolished by tetrodotoxin. Different calcium dependent channels play a role in the formation of both the fast single AP and the slow complex AP in the cartwheel-like cells since all APs were abolished by the use of high concentrations of verapamil. Verapamil dramatically increased the duration of APs in fusiform-like cells and had no effect on tuberculoventral-like cells. In both tuberculoventral-like cells and cartwheel-like cells, 4-aminopyridine (4AP) depolarized the cells and all APs were abolished. Tetraethylammonium chloride (TEA) had a similar effect in cartwheel-like cells. In stellate-like, tuberculoventral-like and fusiform-like cells, the hyperpolarization which followed the AP was abolished by TEA. The AP duration in these cells was also increased by TEA. 4AP had a similar effect in stellate-like and fusiform-like cells. The data for DCN suggest that electrophysiological properties can be used to distinguish and identify neurons.

Membrane properties of complex spike firing neurons of the mouse dorsal cochlear nucleus in vitro.

Intracellular recordings were made from complex spike firing neurons of the mouse dorsal cochlear nucleus (DCN) in vitro. The whole cochlear nucleus was dissected out and maintained submerged in rapidly flowing artificial cerebrospinal fluid (CSF). Recordings were made with current clamp techniques in the presence or absence of ion channel blocking drugs tetrodotoxin (TTX, 1 microM), tetraethylammonium (TEA, 20 mM), 4-aminopyridine (4-AP, 5 mM) or verapamil (50, 100, 150, 250 microM). The cells showed both spontaneous firing and responses to injections of depolarising current consisting of a mixture of a tall single action potential and complexes of 2 to 3 smaller wider action potentials superimposed on a plateau depolarisation. The membrane properties were: resting membrane potential -68.8 +/- 8.5 mV, cell resistance 54.1 +/- 26.5 M omega, time constant 9.6 +/- 5.4 ms and capacitance 0.25 +/- 0.5 nF; the first three variables had bimodel distributions. The current/voltage (I/V) relationship at membrane below resting was non-linear. Previously published histological evidence from the mouse DCN has shown that both cartwheel cells and Purkinje-like neurons are present. Both DCN cartwheel cells and cerebellar Purkinje cells are known to fire both tall single action potentials and complexes of smaller wider action potentials. It is therefore possible that the recordings shown here were made from these neuron types. TTX (1 microM) abolished both the tall single and the complexes of smaller action potentials, suggesting that the tall single action potentials are sodium dependent and possibly that a TTX sensitive sodium channel is responsible for the plateau as is suggested for Purkinje cells in the cerebellum. Verapamil (100 microM) abolished only the complex action potentials and the plateau leaving the tall narrow action potentials intact, which is consistent with the smaller complexes being calcium dependent. Higher concentrations abolished all spiking activity. TEA and 4-AP used separately both caused marked depolarisation to around -20 mV, suggesting that there is a large potassium current active at and near resting.

Membrane properties of mouse anteroventral cochlear nucleus neurons in vitro.

Intracellular recordings were made from neurons of the mouse anteroventral cochlear nucleus (AVCN) in vitro. The whole cochlear nucleus was dissected out and maintained submerged in rapidly flowing artificial CSF. This preparation has the advantages of maintaining cell-to-cell connections and dendritic trees whereas slices and enzymatically separated preparations do not. Recordings were made using current clamp technique in the presence and absence of the ion channel blockers, tetrodotoxin (TTX 1 microM), tetraethylammonium (TEA 20 mM), 4-aminopyridine (4-AP 5 mM) or verapamil (150 microM). Two distinct types of neurons were observed when tested with depolarizing current pulses: one which fired only a single action potential at the onset of stimulation followed by a relative depolarization for the remainder of the stimulus period, and the other which fired a sustained train of action potentials, each followed by a large undershoot, then a rapid recovery phase and the slower depolarization to threshold. The single spike cells (n = 24) had resting membrane potentials of -63.4 +/- 4.7 mV, resistance of 48.4 +/- 29.6 M omega, time constant of 3.47 +/- 3.1 ms, capacitance of 0.081 +/- 0.079 nF. The I/V plot was non-linear above the resting membrane potential and linear below. Spike train cells (n = 24) had resting membrane potentials of -64.2 +/- 4.54 mV, resistance of 69.8 +/- 28.9 M omega, time constant of 6.51 +/- 3.09 ms, capacitance of 0.11 +/- 0.087 nF. The I/V plot was linear both below resting membrane potential and up to threshold for spike firing. TTX abolished spike firing in both cell types. TEA significantly increased the spike duration in both cell types. 4-AP increased the spike duration in spike train cells but not in single spike cells. Verapamil had no effect on the firing properties of both cells but it significantly increased the spike duration of spike train cells. The single spike cells are known to fire rapidly and repetitively in vivo. Injection of sine wave currents caused rapid and repetitive firing suggesting that these cells require hyperpolarization to allow for removal of inactivation. There was a linear relationship between injected depolarizing current and the rate of action potential firing in spike train cells.

Evidence that sodium nitroprusside possesses anticonvulsant effects mediated through nitric oxide.

The effect of sodium nitroprusside (SNP) on epileptiform activity elicited by administration of penicillin (500 units) into the somatomotor cortex was studied in anaesthetized rats. No epileptiform activity was observed after intracortical microinjection of SNP (5 and 20 nM). Microinjection of penicillin into the somatomotor cortex induced epileptiform activity in electrocorticograms (ECoG). Epileptiform discharges elicited by penicillin were significantly decreased by SNP. The effect of SNP appeared within 1 min of application and lasted for 2-5 min. The inhibitory effect of SNP on epileptiform activity could be prevented by pretreatment with methylene blue (20 nM), a soluble guanylate cyclase inhibitor. Prior injection of haemoglobin (5 microliter), a nitric oxide (NO) scavenger, prevented the anticonvulsant effect of SNP. These results suggest that NO may be an endogenous anticonvulsant substance.

The effects of the purinergic system on digitalis-induced epileptiform activity.

It has been suggested that endogenous chemical substances, such as adenosine, released during a seizure attack, may act as anticonvulsants in vivo. We have investigated electrophysiologically the effects of purinoceptor agonists and antagonists on the epileptiform activity induced by intracortical digitalis in anesthetized rats. Intracortical injections of 1, 2, or 4 micrograms digitalis (desacetyl lanatocid C) caused an epileptiform electrocorticogram (ECoG). The application of adenosine (25 or 100 microM) or adenosine triphosphate (ATP) (3 mM) after desacetyl lanatocid C blocked the epileptiform activity. beta, gamma-Methylene ATP (0.1-0.8 mM), a stable analog of ATP, produced inhibition and then death. The epileptogenic effect of desacetyl lanatocid C was enhanced by theophylline (1 mM); however, suramin (1 mM) changed the pattern of epilepsy. These results indicate that the purinergic system may be involved in the mechanism of action of digitalis glycosides.