El complejo pre-Bötzinger: generación y modulación del ritmo respiratorio / Pre-Bötzinger complex: Generation and modulation of respiratory rhythm

Introducción: En los mamíferos, el complejo pre-Bötzinger (preBötC) es una red neuronal bilateral y simétrica localizada en el tallo cerebral, la cual es indispensable para la generación y modulación del ritmo respiratorio. En humanos existen pocos estudios acerca del preBötC y su relación con enfermedades neurológicas no ha sido descrita. Sin embargo, la importancia del preBötC en el control neural del ritmo respiratorio y su posible participación en enfermedades neurológicas en humanos ha sido mostrada gracias a la manipulación farmacológica y de lesiones del preBötC realizadas en modelos animales in vivo e in vitro. Método: En esta revisión describimos los efectos de algunos fármacos sobre la actividad inspiratoria in vitro en el modelo de rebanada transversal del tallo cerebral que contiene el preBötC, y algunos experimentos in vivo. La farmacología fue clasificada de acuerdo con los principales sistemas de neurotransmisión y con la importancia de los fármacos como estimuladores o inhibidores de la actividad del preBötC y, por tanto, de la generación del ritmo respiratorio. Conclusiones: El neurólogo clínico encontrará esta información relevante para entender cómo el sistema nervioso central genera el ritmo respiratorio y, además, podrá relacionarla con las observaciones hechas durante su práctica

Introduction: In mammals, the preBötzinger complex (preBötC) is a bilateral and symmetrical neural network located in the brainstem which is essential for the generation and modulation of respiratory rhythm. There are few human studies about the preBötC and, its relationship with neurological diseases has not been described. However, the importance of the preBötC in neural control of breathing and its potential participation in neurological diseases in humans, has been suggested based on pharmacological manipulation and lesion of the preBötC in animal models, both in vivo and in vitro. Method: In this review, we describe the effects of some drugs on the inspiratory activity in vitro in a transverse slice that contains the preBötC, as well as some in vivo experiments. Drugs were classified according to their effects on the main neurotransmitter systems and their importance as stimulators or inhibitors of preBötC activity and therefore for the generation of the respiratory rhythm. Conclusion: Clinical neurologists will find this information relevant to understanding how the central nervous system generates the respiratory rhythm and may also relate this information to the findings made in daily practice

Pre-Bötzinger complex: Generation and modulation of respiratory rhythm. / El complejo pre-Bötzinger: generación y modulación del ritmo respiratorio.

INTRODUCTION: In mammals, the preBötzinger complex (preBötC) is a bilateral and symmetrical neural network located in the brainstem which is essential for the generation and modulation of respiratory rhythm. There are few human studies about the preBötC and, its relationship with neurological diseases has not been described. However, the importance of the preBötC in neural control of breathing and its potential participation in neurological diseases in humans, has been suggested based on pharmacological manipulation and lesion of the preBötC in animal models, both in vivo and in vitro. METHOD: In this review, we describe the effects of some drugs on the inspiratory activity in vitro in a transverse slice that contains the preBötC, as well as some in vivo experiments. Drugs were classified according to their effects on the main neurotransmitter systems and their importance as stimulators or inhibitors of preBötC activity and therefore for the generation of the respiratory rhythm. CONCLUSION: Clinical neurologists will find this information relevant to understanding how the central nervous system generates the respiratory rhythm and may also relate this information to the findings made in daily practice.

Evaluación temporal del efecto del status epilepticus inducido en la rata en desarrollo en la concentración cerebelar de ácido gama-aminobutírico y glutamato / Time course of the effect of status epilepticus induced in the developing rat on gama-amino butyric acid and glutamate cerebellar concentration

INTRODUCCIÓN: El status epilepticus (SE) es un tipo de actividad epiléptica que causa atrofia cerebelar y pérdida de células de Purkinje en humanos y en animales de experimentación. El cerebelo es una región con alto contenido de ácido gama-aminobutírico (GABA) y glutamato, y algunos estudios refieren cambios en su concentración después de las convulsiones. Sin embargo, hasta la fecha no existen estudios que hayan analizado su efecto en diferentes regiones cerebelares en ratas en desarrollo. El objetivo del presente estudio fue realizar un curso temporal del efecto del SE inducido en ratas Wistar de 14 días de edad (P14) sobre el contenido tisular de GABA y glutamato en el vermis y los hemisferios cerebelares. MÉTODOS: El SE se indujo con el modelo de litio-pilocarpina; las ratas control se inyectaron con salina. Seis h, 24 h o 30 días después del inicio del SE o de la aplicación de solución salina, las ratas se anestesiaron y decapitaron, se extrajo su cerebelo y se separaron el vermis y los hemisferios. Las ratas de ambos grupos se anestesiaron y decapitaron, se extrajo su cerebelo y se separaron el vermis y los hemisferios. Ambas regiones se homogeneizaron (ácido perclórico 0,1 M conteniendo metabisulfito de sodio 4 mM) y centrifugaron, y el sobrenadante se empleó para cuantificar la concentración tisular de GABA y glutamato por cromatografía de líquidos de alta resolución acoplada a un detector fluorométrico. RESULTADOS: El SE no modificó la concentración de GABA y glutamato a los diferentes tiempos de análisis ni en el vermis ni en los hemisferios cerebelares. CONCLUSIONES: El cerebelo en desarrollo es resistente a los cambios neuroquímicos a corto y largo plazo producidos por el SE

INTRODUCTION: Status epilepticus (SE) is an epileptic condition that can cause cerebellar atrophy and loss of Purkinje cells in both humans and research animals. Cerebellum is a region rich in γ-aminobutyric acid (GABA) and glutamate, and some studies have shown that their concentrations may be altered after convulsions. However, there are no studies showing the effect of seizures on different cerebellar regions in developing rats. Time course of the effect of status epilepticus induced in the developing rat on γ-amino butyric acid and glutamate cerebellar concentration. METHODS: SE was induced using the lithium-pilocarpine model; control rats were injected with saline solution. At 6h, 24h, and 1 month after SE o saline injection, rats were anaesthetised with pentobarbital and decapitated, and cerebella were extracted. The vermis and hemispheres were dissected and homogenised in 0.1M perchloric acid containing 4mM sodium bisulfite. Homogenates were centrifuged and supernatant was used to quantify GABA, and glutamate tissue concentrations by HPLC coupled with fluorometric detection. RESULTS: SE did not alter GABA and glutamate tissue concentration in the cerebellar vermis and hemispheres. CONCLUSION: The developing rat cerebellum is resistant to both short- and long-term neurochemical changes induced by SE

Time course of the effect of status epilepticus induced in the developing rat on γ-amino butyric acid and glutamate cerebellar concentration. / Evaluación temporal del efecto del status epilepticus inducido en la rata en desarrollo en la concentración cerebelar de ácido γ-aminobutírico y glutamato.

INTRODUCTION: Status epilepticus (SE) is an epileptic condition that can cause cerebellar atrophy and loss of Purkinje cells in both humans and research animals. Cerebellum is a region rich in γ-aminobutyric acid (GABA) and glutamate, and some studies have shown that their concentrations may be altered after convulsions. However, there are no studies showing the effect of seizures on different cerebellar regions in developing rats. Time course of the effect of status epilepticus induced in the developing rat on γ-amino butyric acid and glutamate cerebellar concentration. METHODS: SE was induced using the lithium-pilocarpine model; control rats were injected with saline solution. At 6h, 24h, and 1 month after SE o saline injection, rats were anaesthetised with pentobarbital and decapitated, and cerebella were extracted. The vermis and hemispheres were dissected and homogenised in 0.1M perchloric acid containing 4mM sodium bisulfite. Homogenates were centrifuged and supernatant was used to quantify GABA, and glutamate tissue concentrations by HPLC coupled with fluorometric detection. RESULTS: SE did not alter GABA and glutamate tissue concentration in the cerebellar vermis and hemispheres. CONCLUSION: The developing rat cerebellum is resistant to both short- and long-term neurochemical changes induced by SE.

Inhibition of endoplasmic reticulum Ca²âº ATPase in preBötzinger complex of neonatal rat does not affect respiratory rhythm generation.

PreBötzinger complex (preBötC) neurons in the brainstem underlie respiratory rhythm generation in vitro. As a result of network interactions, preBötC neurons burst synchronously to produce rhythmic premotor inspiratory activity. Each inspiratory neuron has a characteristic 10-20 mV, 0.3-0.8 s synchronous depolarization known as the inspiratory drive potential or inspiratory envelope, topped by action potentials (APs). Mechanisms involving Ca(2+) fluxes have been proposed to underlie the initiation of the inspiratory drive potential. An important source of intracellular Ca(2+) is the endoplasmic reticulum (ER) in which active Ca(2+) sequestration is mediated by a class of transporters termed sarco/endoplasmic reticulum Ca(2+) ATPases (SERCAs). We aim to test the hypothesis that disruption of Ca(2+) sequestration into the ER affects respiratory rhythm generation. We examined the effect of inhibiting SERCA on respiratory rhythm generation in an in vitro slice preparation. Bath application of the potent SERCA inhibitors thapsigargin or cyclopiazonic acid (CPA) for up to 90 min did not significantly affect the period or amplitude of respiratory-related motor output or integral and duration of inspiratory drive in preBötC neurons. We promoted the depletion of intracellular Ca(2+) stores by a transient bath application of 30 mM K(+) (high K(+)) in the continuous presence of thapsigargin or CPA. After washing out the high K(+), respiratory rhythm period and amplitude returned to baseline values. These results show that after inhibition of SERCA and depletion of intracellular Ca(2+) stores, respiratory rhythm remains substantially the same, suggesting that this source of Ca(2+) does not significantly contribute to rhythm generation in the preBötC in vitro.

A motif present in the main cytoplasmic loop of nicotinic acetylcholine receptors and catalases.

A motif containing five conserved amino acids (RXPXTH(X)14P) was detected in 111 proteins, including 82 nicotinic acetylcholine receptor (nAChR) subunits and 20 catalases. To explore possible functional roles of this motif in nAChRs two approaches were used: first, the motif sequences in nAChR subunits and catalases were analysed and compared; and, second, deletions in the rat alpha2 and beta4 nAChR subunits expressed in Xenopus oocytes were analysed. Compared to the three-dimensional structure of bovine hepatic catalase, structural coincidences were found in the motif of catalases and nAChRs. On the other hand, partial deletions of the motif in the alpha2 or beta4 subunits and injection of the mutants into oocytes was followed by a very weak expression of functional nAChRs; oocytes injected with alpha2 and beta4 subunits in which the entire motif had been deleted failed to elicit any acetylcholine currents. The results suggest that the motif may play a role in the activation of nAChRs.

Transplant of cultured neuron-like differentiated chromaffin cells in a Parkinson's disease patient. A preliminary report.

BACKGROUND: Treatment of Parkinson's Disease (PD) has been attempted by others by transplanting either the patient's own adrenal medullary tissue or fetal substantia nigra into caudate or putamen areas. However, the difficulties inherent in using the patient's own adrenal gland, or the difficulty in obtaining human fetal tissue, has generated the need to find alternative methods. METHODS: We report here of an alternative to both procedures by using as transplant material cultured human adrenal chromaffin cells differentiated into neuron-like cells by extremely low frequency magnetic fields (ELF MF). RESULTS: The results of this study show that human differentiated chromaffin cells can be grafted into the caudate nucleus of a PD patient, generating substantial clinical improvement, as measured by the Unified Rating Scale for PD, which correlated with glucose metabolism and D2 DA receptor increases as seen in a PET scan, while allowing a 70% decrease in L-Dopa medication. DISCUSSION: This is the first preliminary report showing that transplants of cultured differentiated neuron-like cells can be successfully used to treat a PD patient.

The role of voltage-gated Ca2+ channels in neurite growth of cultured chromaffin cells induced by extremely low frequency (ELF) magnetic field stimulation.

The ion Ca2+ has been shown to play an important role in a wide variety of cellular functions, one of them being related to cell differentiation in which nerve growth factor (NGF) is involved. Chromaffin cells obtained from adrenals of 2- to 3-day-old rats were cultured for 7 days. During this time, these cells were subjected to the application of either NGF or extremely low frequency magnetic fields (ELF MF). Since this induced cell differentiation toward neuronal-like cells, the mechanism by which this occurred was studied. When the L-Ca2+ channel blocker nifedipine was applied simultaneously with ELF MF, this differentiation did not take place, but it did when an N-Ca2+ channel blocker was used. In contrast, none of the Ca2+ channel blockers prevented differentiation in the presence of NGF. In addition, Bay K-8644, an L-Ca2+ channel agonist, increased both the percentage of differentiated cells and neurite length in the presence of ELF MF. This effect was much weaker in the presence of NGF. [3H]-noradrenaline release was reduced by nifedipine, suggesting an important role for L-Ca2+ channels in neurotransmitter release. Total high voltage Ca2+ currents were significantly increased in ELF MF-treated cells with NGF, but these currents in ELF MF-treated cells were more sensitive to nifedipine. Amperometric analysis of catecholamine release revealed that the KCl-induced activity of cells stimulated to differentiate by ELF MF is highly sensitive to L-type Ca2+ channel blockers. A possible mechanism to explain the way in which the application of magnetic fields can induce differentation of chromaffin cells into neuronal-like cells is proposed.

Determination of dopamine-releasing protein (DARP) in cerebrospinal fluid of patients with neurological disorders.

Levels of DARP in the cerebrospinal fluid (CSF) of patients having a wide variety of neurological disorders were determined. Neurological disorders were categorized as degenerative, demyelinating, epilepsy, trauma, hydrocephalia, inflammatory, A-V malformation, CNS neoplasia, parasitic and stroke. DARP levels were determined by an enzyme-linked immunoabsorbent assay (ELISA) using monoclonal anti-DARP antibodies. A synthetic peptide corresponding to the first 36 aa of the N-terminal of DARP was used as standard. A total of 7 non-neurological patients and 73 patients with neurological disorders were tested. The relative concentrations of DARP decreased in patients with Parkinson's diseases vs. patients with non-neurological diseases and increased in other neuropathologies such as demyelinating, hydrocephalia and A-V malformations. Data obtained suggest that changes in the percentage and concentration of DARP may correlate with certain neurological disorders, showing particularly low levels in Parkinson's disease patients.

Delay in manifestations of aging by grafting NGF cultured chromaffin cells in adulthood.

Dopamine agonists or grafts compensate impaired motor functions in aged rats. However, there is no evidence showing whether grafting in adulthood retard aging manifestations. Motor performance of 13-month-old rats was tested on 2 meter-long wooden beams which had a 15 degree inclination and whose thickness varied from 3, 6, 12, 18, to 24 mm. Rats at 14 months were randomly assigned to 3 groups: sham graft (Group 1); intrastriatal graft of chromaffin cells cultured with NGF (Group 2); intrastriatal graft of chromaffin cells (Group 3). Motor performance was tested at monthly intervals up until rats were 26 months old. Two more groups were included: 26-month-old naive rats (Group 4); and 3- to 5-month-old naive rats (Group 5) both evaluated only once. At 26 months, the basal activity of ventral mesencephalic dopaminergic neurons was recorded. Results showed in Group 2 delay of motor detriments seen in aged rats, maintenance of basal firing rates of nigral cells compared to those of younger rats, and greater survival of substantia nigra cells. It is suggested that NGF cultured chromaffin cells produce a delay of motor detriments in aged rats, as a result of inducing survival and firing rates of nigral cells comparable to those seen in young rats.

Comparison between low frequency magnetic field stimulation and nerve growth factor treatment of cultured chromaffin cells, on neurite growth, noradrenaline release, excitable properties, and grafting in nigrostriatal lesioned rats.

Adrenal chromaffin cells in vitro respond to nerve growth factor (NGF) by expressing neuronal traits. Low frequency magnetic (LFM) field stimulation, while inducing a variety of effects on several cell types, has never been studies as to its effects on chromaffin cell cultures. The purpose of this study was to compare the effects of LFM field stimulation with that of NGF on the morphological phenotype, on noradrenaline (NA) release, and on membrane excitability of cultured chromaffin cells. We also tested the effects of grafting LFM and NGF-treated chromaffin cells into the caudate nucleus of rats with 6-hydroxydopamine lesions of the nigrostriatal pathway. The results of this study showed that LFM field stimulation produced neurite growth of cultured chromaffin cells in a manner similar to that of NGF exposure. The combination of the two procedures did not induce changes above those observed by NGF alone. Both NGF- and LFM-treated chromaffin cells released [3H]NA equally in response to a depolarizing concentration of KCl. On the other, Na+ current density of LFM field stimulation increased, but to a lesser extent than that seen in NGF-treated cells. In addition both types of cells when transplanted into nigrostriatal-lesioned animals induced a similar decrease in the motor asymmetries produced by the lesion. When NGF- or LFM-treated chromaffin cells where compared to untreated control cells, no significant differences were observed in [3H]NA release, on Na+ current densities, or on postgraft motor asymmetries. The results are discussed in terms of the fact that LFM-stimulated cells can be differentiated in a manner similar to NGF-treated cells, by acquiring sympathetic like traits which in turn can diminish motor asymmetries when grafted into nigrostriatal-lesioned rats.