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1.
Hippocampus ; 24(2): 225-38, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24123729

RESUMO

New neurons are continuously produced in the subgranular zone of the adult hippocampus and can modulate hippocampal plasticity across life. Adolescence is characterized by dramatic changes in sex hormone levels, and social and emotional behaviors. It is also an age for increased risk of psychiatric disorders, including schizophrenia, which may involve altered hippocampal neurogenesis. The extent to which testosterone and other testicular hormones modulate hippocampal neurogenesis and adolescent behavioral development is unclear. This study aimed to determine if removal of testicular hormones during adolescence alters neurogenesis in the male rhesus macaque hippocampus. We used stereology to examine levels of cell proliferation, cell survival and neuronal differentiation in late adolescent male rhesus macaques (4.6-yrs old) that had previously been gonadectomized or sham operated prior to puberty (2.4-yrs old). While the absence of adolescent testicular hormones had no effect on cell proliferation, cell survival was increased by 65% and indices of immature neuronal differentiation were increased by 56% in gonadectomized monkeys compared to intact monkeys. We show for the first time that presence of circulating testicular hormones, including testosterone, may decrease neuronal survival in the primate hippocampus during adolescence. Our findings are in contrast to existing studies in adults where testosterone tends to be a pro-survival factor and demonstrate that testicular hormones may reduce hippocampal neurogenesis during the age typical of schizophrenia onset.


Assuntos
Regulação da Expressão Gênica/fisiologia , Hipocampo/citologia , Neurogênese/fisiologia , Orquiectomia , Animais , Bromodesoxiuridina , Contagem de Células , Diferenciação Celular/fisiologia , Antígeno Ki-67/metabolismo , Macaca mulatta , Masculino , Fosfopiruvato Hidratase/metabolismo , RNA Mensageiro/metabolismo , Testosterona/metabolismo , Proteínas Supressoras de Tumor/metabolismo
2.
Mol Psychiatry ; 18(11): 1185-92, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23070074

RESUMO

Blockade of N-methyl-D-aspartate receptors (NMDARs) produces behavior in healthy people that is similar to the psychotic symptoms and cognitive deficits of schizophrenia and can exacerbate symptoms in people with schizophrenia. However, an endogenous brain disruption of NMDARs has not been clearly established in schizophrenia. We measured mRNA transcripts for five NMDAR subunit mRNAs and protein for the NR1 subunit in the dorsolateral prefrontal cortex (DLPFC) of schizophrenia and control (n=74) brains. Five NMDAR single-nucleotide polymorphisms (SNPs) previously associated with schizophrenia were tested for association with NMDAR mRNAs in postmortem brain and for association with cognitive ability in an antemortem cohort of 101 healthy controls and 48 people with schizophrenia. The NR1 subunit (mRNA and protein) and NR2C mRNA were decreased in postmortem brain from people with schizophrenia (P=0.004, P=0.01 and P=0.01, respectively). In the antemortem cohort, the minor allele of NR2B rs1805502 (T5988C) was associated with significantly lower reasoning ability in schizophrenia. In the postmortem brain, the NR2B rs1805502 (T5988C) C allele was associated with reduced expression of NR1 mRNA and protein in schizophrenia. Reduction in NR1 and NR2C in the DLPFC of people with schizophrenia may lead to altered NMDAR stoichiometry and provides compelling evidence for an endogenous NMDAR deficit in schizophrenia. Genetic variation in the NR2B gene predicts reduced levels of the obligatory NR1 subunit, suggesting a novel mechanism by which the NR2B SNP may negatively influence other NMDAR subunit expression and reasoning ability in schizophrenia.


Assuntos
Cognição , Receptores de N-Metil-D-Aspartato/metabolismo , Esquizofrenia/metabolismo , Psicologia do Esquizofrênico , Adulto , Alelos , Estudos de Casos e Controles , Feminino , Predisposição Genética para Doença/genética , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Córtex Pré-Frontal/metabolismo , Subunidades Proteicas/genética , Receptores de N-Metil-D-Aspartato/genética , Esquizofrenia/genética , Escalas de Wechsler
3.
Transl Psychiatry ; 7(8): e1192, 2017 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-28786974

RESUMO

The immune system is implicated in the pathogenesis of schizophrenia, with elevated proinflammatory cytokine mRNAs found in the brains of ~40% of individuals with the disorder. However, it is not clear if antibodies (specifically immunoglobulin-γ (IgG)) can be found in the brain of people with schizophrenia and if their abundance relates to brain inflammatory cytokine mRNA levels. Therefore, we investigated the localization and abundance of IgG in the frontal cortex of people with schizophrenia and controls, and the impact of proinflammatory cytokine status on IgG abundance in these groups. Brain IgGs were detected surrounding blood vessels in the human and non-human primate frontal cortex by immunohistochemistry. IgG levels did not differ significantly between schizophrenia cases and controls, or between schizophrenia cases in 'high' and 'low' proinflammatory cytokine subgroups. Consistent with the existence of IgG in the parenchyma of human brain, mRNA and protein of the IgG transporter (FcGRT) were present in the brain, and did not differ according to diagnosis or inflammatory status. Finally, brain-reactive antibody presence and abundance was investigated in the blood of living people. The plasma of living schizophrenia patients and healthy controls contained antibodies that displayed positive binding to Rhesus macaque cerebellar tissue, and the abundance of these antibodies was significantly lower in patients than controls. These findings suggest that antibodies in the brain and brain-reactive antibodies in the blood are present under normal circumstances.


Assuntos
Córtex Cerebral/imunologia , Imunoglobulina G/metabolismo , Esquizofrenia/imunologia , Adulto , Animais , Córtex Cerebral/metabolismo , Feminino , Humanos , Imunoglobulina G/sangue , Macaca mulatta , Masculino , Esquizofrenia/metabolismo
4.
Neurotox Res ; 7(1-2): 87-93, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15639801

RESUMO

In recent years metallothionein (MT) biology has moved from investigation of its ability to protect against environmental heavy metals to a wider appreciation of its role in responding to cellular stress, whether as a consequence of normal function, or following injury and disease. This is exemplified by recent investigation of MT in the mammalian brain where plausible roles for MT action have been described, including zinc metabolism, free radical scavenging, and protection and regeneration following neurological injury. Along with other laboratories we have used several models of central nervous system (CNS) injury to investigate possible parallels between injury-dependent changes in MT expression and those observed in the ageing and/or degenerating brain. Therefore, this brief review aims to summarise existing information on MT expression during CNS ageing, and to examine the possible involvement of this protein in the course of human neurodegenerative disease, as exemplified by Alzheimer's disease.


Assuntos
Envelhecimento/metabolismo , Envelhecimento/patologia , Encéfalo/metabolismo , Metalotioneína/fisiologia , Doenças Neurodegenerativas/metabolismo , Doenças Neurodegenerativas/patologia , Encéfalo/citologia , Encéfalo/patologia , Humanos , Metalotioneína/análise , Metalotioneína/biossíntese
5.
Neuroscience ; 298: 190-9, 2015 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-25892701

RESUMO

Anatomical studies have demonstrated that hypocretinergic and GABAergic neurons innervate cells in the nucleus pontis oralis (NPO), a nucleus responsible for the generation of active (rapid eye movement (REM)) sleep (AS) and wakefulness (W). Behavioral and electrophysiological studies have shown that hypocretinergic and GABAergic processes in the NPO are involved in the generation of AS as well as W. An increase in hypocretin in the NPO is associated with both AS and W, whereas GABA levels in the NPO are elevated during W. We therefore examined the manner in which GABA modulates NPO neuronal responses to hypocretin. We hypothesized that interactions between the hypocretinergic and GABAergic systems in the NPO play an important role in determining the occurrence of AS or W. To determine the veracity of this hypothesis, we examined the effects of the juxtacellular application of hypocretin-1 and GABA on the activity of NPO neurons, which were recorded intracellularly, in chloralose-anesthetized cats. The juxtacellular application of hypocretin-1 significantly increased the mean amplitude of spontaneous EPSPs and the frequency of discharge of NPO neurons; in contrast, the juxtacellular microinjection of GABA produced the opposite effects, i.e., there was a significant reduction in the mean amplitude of spontaneous EPSPs and a decrease in the discharge of these cells. When hypocretin-1 and GABA were applied simultaneously, the inhibitory effect of GABA on the activity of NPO neurons was reduced or completely blocked. In addition, hypocretin-1 also blocked GABAergic inhibition of EPSPs evoked by stimulation of the laterodorsal tegmental nucleus. These data indicate that hypocretin and GABA function within the context of a neuronal gate that controls the activity of AS-on neurons. Therefore, we suggest that the occurrence of either AS or W depends upon interactions between hypocretinergic and GABAergic processes as well as inputs from other sites that project to AS-on neurons in the NPO.


Assuntos
Neurônios/fisiologia , Orexinas/metabolismo , Formação Reticular/citologia , Transdução de Sinais/fisiologia , Ácido gama-Aminobutírico/metabolismo , Análise de Variância , Animais , Gatos , Interações Medicamentosas , Estimulação Elétrica , Potenciais Pós-Sinápticos Inibidores/efeitos dos fármacos , Potenciais da Membrana/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Orexinas/farmacologia , Ácido gama-Aminobutírico/farmacologia
6.
J Comp Neurol ; 291(2): 195-202, 1990 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-1967617

RESUMO

The dorsolateral pontine tegmentum of the cat is known to contain enkephalinergic neurons, with most of the enkephalin co-contained in the catecholaminergic neurons; however, enkephalinergic cells projecting to the spinal cord have not been identified. This study employs retrograde transport of horseradish peroxidase in combination with methionine-enkephalin or tyrosine hydroxylase immunocytochemistry to 1) determine the locations of pontospinal enkephalinergic neurons and 2) compare these with the locations of pontospinal catecholaminergic neurons. Pontospinal enkephalinergic neurons were observed in the nuclei locus coeruleus and subcoeruleus and the Kölliker-Fuse nucleus. A high concentration of these neurons was evident in the Kölliker-Fuse nucleus when compared to the nuclei locus coeruleus and subcoeruleus (P less than .01). Both the enkephalinergic and catecholaminergic neurons projecting to the spinal cord were located in the same general areas of the dorsolateral pontine tegmentum and there was no significant difference in the mean diameters of these two neuronal types (P greater than .05). Quantitative data concerning the pontospinal enkephalinergic neurons correlated well with previous data on pontospinal catecholaminergic neurons (Reddy et al., Brain Res. 491:144-149, '89). A majority of the descending neurons from the dorsolateral pontine tegmentum contain enkephalin (72-80%) and catecholamine (80-87%). The observations suggest that enkephalin is contained in many of the pontospinal catecholaminergic neurons.


Assuntos
Catecolaminas/metabolismo , Encefalina Metionina/metabolismo , Locus Cerúleo/metabolismo , Medula Espinal/metabolismo , Animais , Gatos , Vias Eferentes/anatomia & histologia , Locus Cerúleo/citologia , Medula Espinal/citologia , Tirosina 3-Mono-Oxigenase/metabolismo
7.
Neuropharmacology ; 32(7): 621-31, 1993 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-8361578

RESUMO

Electrical stimulation of the dorsolateral pontine tegmentum (DLPT) produces phasic facilitatory and inhibitory actions on the lumbar spinal monosynaptic reflexes (MSRs) of both flexor and extensor muscle nerves in the decerebrate cat. Naloxone, an opioid receptor antagonist, given intravenously or intraspinally enhanced the DLPT-induced potentiation of MSRs in most of the reflexes studied. However, systemic naloxone had no significant effect on the unconditioned MSR of the spinal cord. Intraspinal microinjections of naloxone significantly attenuated the DLPT-induced inhibition of MSRs of both flexors and extensors, similar to the action of systemic injection of naloxone, indicating a direct opioid action at the spinal ventral horn level upon DLPT stimulation. Results of the present experiment further support the anatomical finding that there are pontospinal enkephalinergic pathways in the cat, and indicate that these descending pathways modulate spinal motor outflow.


Assuntos
Endorfinas/fisiologia , Ponte/fisiologia , Reflexo Monosináptico/fisiologia , Medula Espinal/fisiologia , Tegmento Mesencefálico/fisiologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Tronco Encefálico/fisiologia , Gatos , Estado de Descerebração/fisiopatologia , Estimulação Elétrica , Eletrodos , Encefalina Metionina/fisiologia , Feminino , Injeções , Injeções Intravenosas , Masculino , Neurônios Motores/fisiologia , Naloxona/farmacologia , Ponte/anatomia & histologia , Reflexo Monosináptico/efeitos dos fármacos , Medula Espinal/anatomia & histologia , Medula Espinal/efeitos dos fármacos , Sinapses/efeitos dos fármacos , Tegmento Mesencefálico/anatomia & histologia
8.
Neuroscience ; 64(1): 193-208, 1995 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-7708205

RESUMO

Glutamate is considered to be a major excitatory neurotransmitter in the central nervous system. The presence of glutamate-like immunoreactive neurons in the rodent locus coeruleus has been reported previously. In this study we used both immunohistochemical and electrophysiological techniques to answer two major questions: (1) Is there any glutamate-like immunoreactivity in the catecholaminergic coeruleospinal system of the cat? (2) What is the physiological role, if any, of glutamate in descending locus coeruleus control of spinal motoneurons? Following injections of rhodamine-labeled latex microspheres or Fast Blue into the seventh lumbar segment of the spinal cord of the cat, retrogradely labeled cells were found throughout the rostrocaudal extent of the dorsolateral pontine tegmentum. They were primarily observed in the nucleus locus coeruleus and the Kolliker-Fuse nucleus. Some labeled cells were also present in the nucleus subcoeruleus and, to a lesser extent, in the parabrachial nuclei. Data from immunohistochemical studies indicate that 86% of all dorsolateral pontine tegmentum neurons that project to the spinal cord contain glutamate-like immunoreactivity, and 77% co-contain both glutamate- and tyrosine hydroxylase-like immunoreactivity. Electrical stimulation (four pulses of 500 microseconds duration at 500 Hz; intensity = 50-200 microA) of the locus coeruleus, in decerebrate cats, consistently induced lumbar motoneuron discharges recordable ipsilaterally as ventral root responses. These motoneuronal responses were reversibly antagonized following chemical inactivation of noradrenergic locus coeruleus neurons by local infusion of the alpha 2-adrenergic agonist clonidine, suggesting the locus coeruleus neurons to be the main source of evoked ventral root responses. Additionally, the evoked ventral root responses were reversibly reduced by 34.20 +/- 4.45% (mean +/- S.E.M.) upon intraspinal injections of the non-N-methyl-D-aspartate receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione, into the ventral horn of seventh lumbar spinal cord segment (three to four injections, 20 nmol in 0.2 microliter of 0.1 M Tris-buffered saline for each injection). Similar volumes of vehicle injections had no significant effect on the locus coeruleus-evoked ventral root responses. These ventral root responses were also partially blocked (62.30 +/- 11.76%) by intravenous administration of the alpha 1-adrenergic receptor antagonist prazosin (20 micrograms/kg). In the light of several anatomical reports of noradrenergic and glutamatergic terminals in close contact with spinal motoneurons, our present findings suggest that the locus coeruleus-evoked ventral root response probably involves the synaptic release of both norepinephrine and glutamate onto lumbar motoneurons.(ABSTRACT TRUNCATED AT 400 WORDS)


Assuntos
Locus Cerúleo/fisiologia , Neurônios Motores/fisiologia , Neurônios/fisiologia , Medula Espinal/fisiologia , 6-Ciano-7-nitroquinoxalina-2,3-diona/farmacologia , Animais , Gatos , Clonidina/farmacologia , Relação Dose-Resposta a Droga , Ácido Glutâmico , Locus Cerúleo/ultraestrutura , Região Lombossacral , Nervo Fibular/fisiologia , Prazosina/farmacologia
9.
Neuroscience ; 94(1): 11-5, 1999.
Artigo em Inglês | MEDLINE | ID: mdl-10613491

RESUMO

The obstructive sleep apnea syndrome is characterized by the occurrence of cyclic snoring and frequent apneic episodes during sleep, with consequent hypoxia and hypercapnia. Obstructive sleep apnea syndrome is associated with excess daytime sleepiness, depression, and an increased incidence of ischemic cardiopathy, cardiac arrhythmias, systemic hypertension and brain infarction. Hypoglossal motoneurons, which innervate extrinsic and intrinsic muscles of the tongue, play a key role in maintaining the patency of the upper airway and in the pathophysiology of obstructive sleep apnea syndrome. Based on data obtained by using extracellular recording techniques, there is a consensus that hypoglossal motoneurons cease to discharge during rapid eye movement sleep, because they are disfacilitated. Since other somatic motoneurons are known to be postsynaptically inhibited during rapid eye movement sleep, we sought to determine, by the use of intracellular recording techniques during cholinergically induced rapid eye movement sleep, whether postsynaptic inhibitory mechanisms act on hypoglossal motoneurons. We found that, during this state, a powerful glycinergic premotor inhibitory system acts to suppress hypoglossal motoneurons. This finding opens new avenues for the treatment of obstructive sleep apnea syndrome, and provides a foundation to explore the neural and pharmacological control of respiration-related motoneurons during rapid eye movement sleep.


Assuntos
Carbacol/farmacologia , Agonistas Colinérgicos/farmacologia , Nervo Hipoglosso/citologia , Neurônios Motores/fisiologia , Inibição Neural/fisiologia , Sono REM/fisiologia , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Animais , Gatos , Glicina/fisiologia , Nervo Hipoglosso/fisiologia , Ponte/efeitos dos fármacos , Ponte/fisiologia , Respiração , Formação Reticular/efeitos dos fármacos , Formação Reticular/fisiologia , Apneia Obstrutiva do Sono/tratamento farmacológico , Apneia Obstrutiva do Sono/fisiopatologia , Sono REM/efeitos dos fármacos , Sinapses/fisiologia
10.
Prog Brain Res ; 88: 343-50, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-1813925

RESUMO

Intracellular recordings from cat spinal motoneurons in situ demonstrated that microiontophoretic application of NE with low-intensity ejection currents produces a slowly developing, small-amplitude depolarization of the cells, in contrast to early reports of NE-induced hyperpolarization. This depolarization was associated with an increase in excitability of the cells and a decrease in membrane conductance. These observations are consistent with the hypothesis that NE reduces potassium conductance in spinal motoneurons as has been proposed for facial motoneurons (VanderMaelen and Aghajanian, 1980) and thalamic neurons (McCormick and Prince, 1988). The time course of the facilitatory effects of NE on cat motoneuron excitability recorded intracellularly agreed very closely with the time course of NE-induced facilitation of glutamate-evoked excitability in rat spinal motoneurons recorded extracellularly. The similarity of the observations in rats and cats suggests that NE functions generally to enhance mammalian motoneuron responsiveness to excitatory input.


Assuntos
Neurônios Motores/efeitos dos fármacos , Norepinefrina/fisiologia , Medula Espinal/efeitos dos fármacos , Potenciais de Ação/efeitos dos fármacos , Fibras Adrenérgicas/efeitos dos fármacos , Fibras Adrenérgicas/fisiologia , Animais , Gatos , Estado de Descerebração/fisiopatologia , Nervo Facial/efeitos dos fármacos , Nervo Facial/fisiologia , Ativação do Canal Iônico/efeitos dos fármacos , Iontoforese , Locus Cerúleo/fisiologia , Norepinefrina/farmacologia , Ponte/fisiologia , Potássio/fisiologia , Ratos , Serotonina/farmacologia , Medula Espinal/citologia
11.
Prog Brain Res ; 88: 103-21, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-1687616

RESUMO

The dorsolateral pontine tegmentum of the cat is known to contain a large population of catecholaminergic neurons. Additionally, several studies have also shown the presence of other neurochemicals (acetylcholine, enkephalin, neuropeptide Y, serotonin, somatostatin and substance P). In this study, we have employed retrograde transport of horseradish peroxidase in combination with immunocytochemistry to determine the locations of pontospinal neurons which contain catecholamine, enkephalin, neuropeptide Y, and serotonin. Furthermore, we have combined the retrograde transport of Fast Blue and immunofluorescence histochemistry to determine whether enkephalin-containing neurons are catecholaminergic. All pontospinal neurons, irrespective of the neurochemical content, were observed in the ventral and lateral parts of the dorsolateral pontine tegmentum at coronal levels P1.8-P4.0. These neurons were located in the nuclei locus coeruleus alpha and subcoeruleus and the Kölliker-Fuse nucleus. A high concentration of these neurons was evident in the Kölliker-Fuse nucleus when compared to the nuclei locus coeruleus alpha and subcoeruleus. Quantitative data have revealed that enkephalin is contained in a large proportion of the pontospinal catecholaminergic neurons (75%). The observations suggest that catecholaminergic neurons may contain one or more putative peptide neurotransmitters.


Assuntos
Neurotransmissores/análise , Ponte/química , Medula Espinal/química , Animais , Mapeamento Encefálico , Gatos , Locus Cerúleo/química , Locus Cerúleo/fisiologia , Neurônios/química , Ponte/fisiologia , Medula Espinal/fisiologia
12.
Prog Brain Res ; 88: 395-409, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-1667549

RESUMO

Using electrophysiological techniques, we investigated the functional properties of the coeruleospinal system for regulating the somatomotor outflow at lumbar cord levels. Many of the fast-conducting, antidromically activated coeruleospinal units were shown to exhibit the alpha 2-receptor response common to noradrenergic locus coeruleus (LC) neurons. Electrically activating the coeruleospinal system potentiated the lumbar monosynaptic reflex and depolarized hindlimb flexor and extensor motoneurons via an alpha 1-receptor mechanism. The latter synaptically induced membrane depolarization was mimicked by norepinephrine applied iontophoretically to motoneurons. That LC inhibited Renshaw cell activity and induced a positive dorsal root potential at the lumbar cord also reinforced LC's action on motor excitation. We conclude that LC augments the somatomotor output, at least in part, via an alpha 1-adrenoceptor-mediated excitation of ventral horn motoneurons. Such process is being strengthened by LC's suppression of the recurrent inhibition pathway as well as by its presynaptic facilitation of afferent impulse transmission at the spinal cord level.


Assuntos
Locus Cerúleo/fisiologia , Neurônios Motores/fisiologia , Norepinefrina/fisiologia , Medula Espinal/fisiologia , Potenciais de Ação/efeitos dos fármacos , Vias Aferentes/fisiologia , Animais , Gatos , Estado de Descerebração/fisiopatologia , Vias Eferentes/fisiologia , Estimulação Elétrica , Neurônios Motores/efeitos dos fármacos , Norepinefrina/farmacologia , Primatas , Ratos , Receptores Adrenérgicos alfa/efeitos dos fármacos , Receptores Adrenérgicos alfa/fisiologia
13.
J Chem Neuroanat ; 5(1): 1-10, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1351395

RESUMO

Previous studies have revealed the presence of pontospinal neurons with either methionine-enkephalin- or tyrosine hydroxylase-like immunoreactivity in the dorsolateral pontine tegmentum of the cat. Using a combined fast blue retrograde transport technique and simultaneous immunofluorescence histochemistry, the present study was designed to reveal the coexistence of enkephalin and tyrosine hydroxylase in cat coerulospinal neurons and to determine if and to what extent the coerulospinal pathway is heterogeneous. Fast blue-labelled neurons with tyrosine hydroxylase- and enkephalin-like immunoreactivities were found in the nucleus locus coeruleus, nucleus subcoeruleus, Kölliker-Fuse nucleus, and the medial and lateral parabrachial nuclei. Approximately 87% of tyrosine hydroxylase-like immunoreactive neurons had enkephalin-like immunoreactivity, whereas about 76% of the enkephalin-like immunoreactive neurons had tyrosine hydroxylase-like immunoreactivity. About 71% of all coerulospinal neurons exhibited both tyrosine hydroxylase- and enkephalin-like immunoreactivities. These findings indicate that coerulospinal activity may lead to spinal cord effects reflecting both norepinephrine and enkephalin activity in most cases but do not rule out each transmitter's isolated functions.


Assuntos
Encefalina Metionina/metabolismo , Locus Cerúleo/metabolismo , Neurônios/metabolismo , Medula Espinal/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Amidinas , Animais , Tronco Encefálico/citologia , Tronco Encefálico/enzimologia , Tronco Encefálico/metabolismo , Gatos , Imunofluorescência , Imuno-Histoquímica , Locus Cerúleo/citologia , Locus Cerúleo/enzimologia , Vias Neurais/citologia , Vias Neurais/enzimologia , Vias Neurais/metabolismo , Neurônios/enzimologia , Norepinefrina/metabolismo , Medula Espinal/citologia , Medula Espinal/enzimologia
14.
Microsc Res Tech ; 29(3): 219-25, 1994 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-7849326

RESUMO

This paper reviews the anatomical evidence for the presence of glutamate (GLU) in noradrenergic neurons of the nucleus locus coeruleus (LC) and adjacent nuclei in the dorsolateral pontine tegmentum (DLPT) that project to the spinal cord, cerebellum, or cerebral cortex. Additionally, the evidence for the existence of methionine-enkephalin (ENK) in noradrenergic neurons of the DLPT that project to the spinal cord of the cat is reviewed. In these studies, we have combined the retrograde transport of either Fast Blue (FB), rhodamine labeled latex microspheres (MS), or rhodamine labeled dextran and indirect immunofluorescence histochemistry to determine whether the neurons that contain tyrosine hydroxylase (TH) and project to these terminal fields also contain GLU or ENK. The neurons of the cat that project to the spinal cord, cerebellum, and neocortex were observed in the nucleus LC and Kölliker-Fuse (KF) nucleus. They were also present, to a lesser extent, in the nucleus subcoeruleus (SC) and nuclei parabrachialis medialis (PBM) and lateralis (PBL). In the rat the majority of the neurons that project to the neocortex and hippocampus were located in the nucleus LC. Our data revealed a major proportion of these neurons to be immunostained for both GLU and TH (cat, rat), or ENK and TH (cat). Functional implications of such colocalized neurochemicals within individual LC projection neurons are discussed.


Assuntos
Encefalina Metionina/análise , Ácido Glutâmico/análise , Locus Cerúleo/química , Neurônios/química , Norepinefrina/análise , Animais , Gatos , Imunofluorescência , Locus Cerúleo/enzimologia , Locus Cerúleo/ultraestrutura , Microesferas , Neurônios/enzimologia , Neurônios/ultraestrutura , Ponte/química , Ponte/ultraestrutura , Ratos , Rodaminas , Tirosina 3-Mono-Oxigenase/análise
15.
Peptides ; 12(4): 739-43, 1991.
Artigo em Inglês | MEDLINE | ID: mdl-1788136

RESUMO

Spinally projecting neuropeptide Y (NPY)-immunoreactive cells were sought in the feline locus coeruleus (LC) nuclear complex after horseradish peroxidase (HRP) injection into the lumbar cord; HRP injection was followed by intracerebroventricular colchicine administration. Our results revealed that a significant number (approximately 20% of all descending cells from the LC complex) of spinally projecting NPY-immunoreactive neurons arise from the LC alpha, the subcoeruleus and the Kölliker-Fuse nuclei. Other nonspinally projecting NPY-containing cells were also evident in the laterodorsal tegmental nucleus and the LCd, in addition to those occurring in the aforementioned LC nuclear complex.


Assuntos
Locus Cerúleo/metabolismo , Neuropeptídeo Y/metabolismo , Animais , Gatos , Imuno-Histoquímica , Locus Cerúleo/citologia , Neurônios/metabolismo
16.
J Neurosci Methods ; 40(2-3): 113-20, 1991 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-1800847

RESUMO

Glass microelectrodes filled with electrolyte solutions are standard tools for electrophysiological studies. However, for any given application, there are limitations to the properties of the microelectrode, such as impedance and shank length, that can yield satisfactory results. The trial and error approach in pulling electrodes with the desired properties can be time consuming. The use of a response surface procedure which allows the experimenter to change more than one factor at a time and therefore determine the desired puller condition more efficiently is demonstrated. Also, design improvements for the World Precision Instrument, Model PUL-1, Microelectrode puller, used in this study are suggested.


Assuntos
Eletrofisiologia/métodos , Microeletrodos , Animais , Linhagem Celular , Eletrofisiologia/instrumentação , Vidro , Humanos , Matemática , Neuroblastoma , Soluções
17.
J Neurosci Methods ; 41(2): 113-21, 1992 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-1564947

RESUMO

Two programs are described which use an IBM-AT compatible personal computer, equipped with an analog-to-digital converter, to collect and analyze electrophysiological data. The first program is used to determine neuron firing rates during intracellular experiments and to save these results on disk. The second program is used to perform off-line analysis of the frequency data. Both programs are written entirely in the well known BASIC language and the Microsoft QuickBASIC compiler is employed for their use. All of the necessary hardware can be purchased commercially. In this paper emphasis is placed on the strategies and limitations involved when this high-level language is applied to tasks often needed in data acquisition and analysis. Both on- and off-line collection schemes are considered. This software is available from the authors.


Assuntos
Coleta de Dados/instrumentação , Processamento Eletrônico de Dados , Neurônios/fisiologia , Linguagens de Programação , Software , Animais , Eletrofisiologia , Lymnaea
18.
Biosens Bioelectron ; 7(2): 91-101, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1637528

RESUMO

Results are presented which enhance the field of neuron-based sensing by providing insight on the effects of operating temperature and analyte application technique (pulse versus back-mixed) on sensing properties. In these studies, serotonin sensing attributes of giant visceral neurons VV1 and VV2 from the pond snail Lymnea stagnalis were measured. Experiments using a rapid fluid-exchange system reveal a concentration-dependent increase in maximum firing frequency similar to that reported earlier for a slow well-mixed application. With a rapid application, however, the maximum firing frequency is reached more quickly, and there is less cell-to-cell variability in both the maximum response and sensitivity. Given an application technique, an increase in temperature causes an increase in sensitivity and maximum firing frequency, as well as a decrease in the time required for the response to return to baseline following removal of the analyte. To provide insights on the kinetics of the serotonin-induced response, the effects of temperature and concentration on the rates of activation, recovery and desensitization were examined in detail. In general, it was found that an increase in temperature increases the rates of activation and desensitization, while the effects on recovery were not apparent. In addition, both the rates of activation and desensitization have a direct dependence on concentration while the rate of recovery has an inverse dependence.


Assuntos
Técnicas Biossensoriais , Lymnaea/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Serotonina/farmacologia , Temperatura , Potenciais de Ação/efeitos dos fármacos , Animais , Gânglios/efeitos dos fármacos , Cinética , Métodos , Sensibilidade e Especificidade
19.
Biosens Bioelectron ; 5(6): 491-510, 1990.
Artigo em Inglês | MEDLINE | ID: mdl-2271148

RESUMO

Results are presented on the development of a novel biosensor which will use neurons or neuronal components as both the recognition elements and primary transducers for analyte quantitation. This concept is demonstrated and evaluated by exposing identified neurons from the visceral ganglia of the pond snail Limnea stagnalis to the model analyte serotonin. Experiments reveal a reversible, concentration-dependent increase in the rate of spontaneous action potential generation, over a concentration range of four orders of magnitude. Studies with the antagonist methysergide verify that this response is mediated through serotonin-sensitive receptors. Exposure of the neurons to serotonin causes the firing frequency to rapidly increase to a maximum and then slowly diminish to a sub-optimal level. It was found that the maximum frequency provides an indication of chemical concentration that is repeatable. Data are also presented which further advance the field of neuronal biosensing by demonstrating both the effects of cell to cell variability on response reproducibility and the effects of the desensitizing response on the operation of a neuron-based sensor in both a continuous and discontinuous mode.


Assuntos
Técnicas Biossensoriais , Neurônios , Serotonina/análise , Potenciais de Ação/efeitos dos fármacos , Animais , Eletrofisiologia , Estudos de Avaliação como Assunto , Técnicas In Vitro , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Serotonina/farmacologia , Caramujos
20.
Brain Res ; 402(2): 230-42, 1987 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-3828795

RESUMO

The present analysis describes the cellular mechanisms underlying the heightened membrane excitability of hindlimb flexor and extensor motoneurons upon stimulation of the locus coeruleus (LC) in unanesthetized, decerebrate cats. In a total of 73 cells, brief train stimuli to the LC at 50-300 microA intensity evoked one of 4 patterns of motoneuronal responses: a simple excitatory postsynaptic potential (EPSP) with weak trailing depolarization, a double-peak EPSP, an EPSP succeeded by a weak hyperpolarization, or a slow rising EPSP. As the initial dominant EPSP was a consistent finding among all cells and the ensuing potentials were variable in polarity, quantitative characterization was focused on the initial EPSP only. In all cells tested (n = 11), the LC-EPSP was accompanied by a decrease in input resistance. The excitatory LC action was further demonstrated by the consistent (n = 25 cells) motoneuron rheobase decrease when the latter was measured coincident with the summit of an LC-EPSP. Furthermore, the time course of the single-spike afterhyperpolarization became shortened during the LC conditioning stimuli (n = 16 motoneurons). Our data show that the descending LC action on motoneurons is typified by an EPSP accompanied by a net decrease in input resistance as well as a concurrent increase in motoneuron electrical excitability.


Assuntos
Membro Posterior/inervação , Locus Cerúleo/fisiologia , Neurônios Motores/fisiologia , Animais , Gatos , Membrana Celular/fisiologia , Condutividade Elétrica , Estimulação Elétrica , Eletrofisiologia , Sinapses/fisiologia
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