RESUMO
We report the existence and anatomical distribution to nociceptin/orphanin-FQ (N/O FQ)-like immunoreactivity in neurons and fibers in the perioesophageal ganglia of the snail (Helix aspersa). Intracellular recordings from perioesophageal ganglion neurons showed that the application of 10 microM N/O FQ produced an excitatory action in 22% of the neurons studied and an inhibitory action in 33% of the neurons regardless of their origin (cerebral or parietal ganglion). Our result provides evidence that N/O FQ-like peptide is located in whole perioesophageal ganglia (mainly in the cerebral one), and that it may serve as a neuromodulator of the neuronal spike discharge. These data support the idea that the N/O FQ opioid system has an early phylogenetic origin and a functional continuity during the course of evolution.
Assuntos
Encéfalo/metabolismo , Gânglios dos Invertebrados/metabolismo , Caracois Helix/metabolismo , Neurônios/metabolismo , Peptídeos Opioides/metabolismo , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Animais , Encéfalo/citologia , Encéfalo/efeitos dos fármacos , Relação Dose-Resposta a Droga , Gânglios dos Invertebrados/citologia , Gânglios dos Invertebrados/efeitos dos fármacos , Caracois Helix/citologia , Imuno-Histoquímica , Neurônios/citologia , Neurônios/efeitos dos fármacos , Peptídeos Opioides/farmacologia , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologia , NociceptinaRESUMO
The aim of this study was to describe the anatomic distribution of neuronal nitric oxide synthase immunoreactivity (nNOS-IR) and nicotinamide-adenine dinucleotide phosphate-diaphorase (NADPH-d) staining in the olfactory epithelium of the axolotl, juvenile, and neotenic adult, Ambystoma mexicanum. Nitric oxide (NO, nitrogen monoxide) is a widespread molecule that has been identified both as a neuromodulator and as an intracellular messenger. In the olfactory system, NO has been proposed to play a role in olfactory transduction. Nitric oxide synthase (NOS) can be detected by histochemical (NADPH-d) and immunohistochemical techniques. NADPH-d staining has been described in olfactory receptor neurons (ORN) of several species; however, nNOS-IR has not always been found at ORN. Present results show intense NADPH-d staining and nNOS-IR in the dendrites and cell bodies of ORN in both the nasal cavity and the vomeronasal organ of axolotls. Unilateral olfactory axotomy was conducted to confirm that labels were at ORN. Two weeks after this procedure an important decrease in NADPH-d staining and nNOS-IR was observed. The remaining labels were mostly in basal cells. By 5 weeks postaxotomy both labels were almost totally absent. Thus, both NADPH-d staining and nNOS-IR were mainly localized in ORN. NADPH-d staining and nNOS-IR were also found in nerve fibers surrounding arterioles, as well as in secretory and duct cells of the Bowman's glands. This last anatomical localization suggests that in the A. mexicanum NO might be involved in functions other than only olfactory transduction, such as regulation of local blood flow, glandular secretion, and ORN development.
Assuntos
NADPH Desidrogenase/análise , Fibras Nervosas/enzimologia , Óxido Nítrico Sintase/análise , Mucosa Olfatória/enzimologia , Ambystoma/anatomia & histologia , Ambystoma/fisiologia , Animais , Dendritos/enzimologia , Imuno-Histoquímica/métodos , Técnicas In Vitro , Distribuição Tecidual/fisiologiaRESUMO
Efflux of Cl(-) through GABA(A)-gated anion channels depolarizes the cell bodies and intraspinal terminals of sensory neurons, and contributes to the generation of presynaptic inhibition in the spinal cord. Active accumulation of Cl(-) inside sensory neurons occurs through an Na(+)-K(+)-2Cl(-) cotransport system that generates and maintains the electrochemical gradient for this outward Cl(-) current. We studied the immunolocalization of the Na(+)-K(+)-2Cl(-) cotransporter protein using a monoclonal antibody (T4) against a conserved epitope in the C-terminus of the molecule. Western blots of frog, rat and cat dorsal root ganglion membranes revealed a single band of cotransporter immunoreactivity at approximately 160kDa, consistent with the molecular mass of the glycosylated protein. Deglycosylation with N-glycosidase F reduced the molecular mass to approximately 135kDa, in agreement with the size of the core polypeptide. Indirect immunofluorescence revealed strong cotransporter immunoreactivity in all types of dorsal root ganglion cell bodies in frog, rat and cat. The subcellular distribution of cotransporter immunoreactivity was different amongst species. Membrane labeling was more apparent in frog and rat dorsal root ganglion cell bodies than in cat. In contrast, cytoplasmic labeling was intense in cat and weak in frog, being intermediate in the rat. Cotransporter immunoreactivity also occurred in satellite cells, particularly in rat and cat dorsal root ganglia. The membrane region and axoplasm of sensory fibers were heavily labeled in cat and rat and less in frog. Three-dimensional reconstruction of confocal optical sections and dual immunolocalization with S-100 protein showed that the cotransporter immunoreactivity was prominently expressed in the nodal and paranodal regions of the Schwann cells. Ultrastructural immunolocalization confirmed the presence of immunoreactivity on the membranes of the axon and the Schwann cell in both the nodal region and the paranode. Treatment with sodium dodecylsulfate and beta-mercaptoethanol also uncovered intense cotransporter immunoreactivity in Schmidt-Lanterman incisures at the light microscopic level. The localization of the Na(+)-K(+)-2Cl(-) cotransporter protein is consistent with its function as a Cl(-)-accumulating mechanism in sensory neurons. Its distinctive presence in Schwann cells suggests that it could also be involved in K(+) uptake from the extracellular space, particularly in the paranodal region of myelinated axons, thereby regulating the extracellular ionic environment and the excitability of axons.
Assuntos
Potenciais de Ação/fisiologia , Proteínas de Transporte/metabolismo , Gânglios Espinais/metabolismo , Inibição Neural/fisiologia , Neurônios Aferentes/metabolismo , Nós Neurofibrosos/metabolismo , Células de Schwann/metabolismo , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/isolamento & purificação , Especificidade de Anticorpos , Gatos , Imunofluorescência , Gânglios Espinais/ultraestrutura , Microscopia Confocal , Microscopia Eletrônica , Fibras Nervosas Mielinizadas/metabolismo , Fibras Nervosas Mielinizadas/ultraestrutura , Neurônios Aferentes/ultraestrutura , Ranidae , Nós Neurofibrosos/ultraestrutura , Ratos , Células de Schwann/ultraestrutura , Simportadores de Cloreto de Sódio-Potássio , Vertebrados/anatomia & histologia , Vertebrados/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
Oral administration of aqueous red pepper (Capsicum frutescens, Cf) solution and low capsaicin (8-methyl-N-vanillyl-6-nonenamide) doses during gestation produces an increase in the latency of the thermonociceptive escape response of rat offspring. The present work shows that different amounts of Cf (10%, 25% and 50%) incorporated to normal food of gestating rats modify in a dose-dependent manner the flexion reflex latency (R), as well as the latency of appearance of antialgesic behaviours expressed as paw lick (P) and escape response (E) using the hot plate test (53 degrees C+/-0.5 degrees C). The latency of the same parameters was tested in the same subjects 55 days later to determine the persistence of this effect. Results show an increase in latency of the three parameters R, P and E in all experimental groups with respect to controls. Animals (Cf, 25% group) tested 55 days after the first test exhibited latencies similar to controls, which suggests that the process is reversible.
Assuntos
Capsaicina/farmacologia , Capsicum , Nociceptores/efeitos dos fármacos , Limiar da Dor/efeitos dos fármacos , Extratos Vegetais/farmacologia , Plantas Medicinais , Efeitos Tardios da Exposição Pré-Natal , Tempo de Reação/efeitos dos fármacos , Sensação Térmica/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Reação de Fuga/efeitos dos fármacos , Feminino , Gravidez , Ratos , Ratos WistarRESUMO
Nicotinamide adenine dinucleotide phosphate reduced-diaphorase (NADPH-d) histochemistry was investigated in the axolotl (Ambystoma tigrinum) inner ear. Hair cells showed an intense NADPH-d reaction; afferent neurones also stained but less intensely than hair cells. Effects of NG-nitro-L-arginine (L-NOARG) on the basal discharge and mechanical responses of semicircular canal afferent neurones recorded extracellularly were also studied. L-NOARG (1 mu M) diminished the basal discharge and the response of afferent neurones to sinusoidal mechanical stimuli to 45 +/- 6.4% and 65 +/- 5.3% (mean +/- SEM) of control value, respectively. These findings suggest that production of nitric oxide (NO) by hair cells and probably also by afferent neurones contributes to the basal discharge and the response of afferent neurones to mechanical stimuli.
Assuntos
Ambystoma/metabolismo , Orelha Interna/enzimologia , Óxido Nítrico Sintase/metabolismo , Animais , Orelha Interna/citologia , Eletrofisiologia , Inibidores Enzimáticos/farmacologia , Potenciais Evocados/efeitos dos fármacos , Células Ciliadas Vestibulares/efeitos dos fármacos , Células Ciliadas Vestibulares/enzimologia , Histocitoquímica , NADPH Desidrogenase/metabolismo , Neurônios Aferentes/efeitos dos fármacos , Neurônios Aferentes/enzimologia , Neurônios Eferentes/efeitos dos fármacos , Neurônios Eferentes/enzimologia , Nitroarginina/farmacologiaRESUMO
In this paper we discuss the anatomical localization of NADPH-diaphorase using Nitroblue tetrazolium in perioesophageal ganglia of Helix aspersa. Our results show that the reaction is present in neurons and fibers of the procerebrum, some positive neurons are found in mesocerebrum, and there were positive fibers in the neuropile of postcerebrum and mesocerebrum; likewise, immunopositive fibers were found in the neuropile of pedal, pleural and parietal ganglia. The presence of NADPH-diaphorase in the interneurons of procerebrum suggests the participation of this enzyme in the production of nitric oxide for the processing of the olfactory information, as has been suggested in mammalian olfactory tissue.
Assuntos
Gânglios dos Invertebrados/enzimologia , NADPH Desidrogenase/metabolismo , Animais , Gânglios dos Invertebrados/anatomia & histologia , Gânglios dos Invertebrados/metabolismo , Caracois Helix , Histocitoquímica , Interneurônios/enzimologia , Interneurônios/fisiologia , Óxido Nítrico/biossíntese , Nitroazul de TetrazólioRESUMO
An immunohistochemical study of opioid peptides in the hypophysis of the axolotl, Ambystoma mexicanum, was carried out with antisera against leu-enkephalin, beta-endorphin, met-enkephalin, and dynorphin A (1-8). We found leu-enkephalin immunoreactivity in some fibers of the neural lobe and the median eminence. In contrast to previous reports on mammals and other vertebrates, we found leu-enkephalin immunoreactivity in many cells scattered throughout the anterior lobe. As in other vertebrates, the beta-endorphin immunoreactivity was present in all the cells of the intermediate lobe and in a few cells of the anterior lobe. Met-enkephalin and dynorphin A (1-8) immunoreactivities were only present in the neural lobe and the median eminence. The presence of leu-enkephalin and beta-endorphin in the anterior lobe suggests that these peptides could be acting as hormones released from the hypophysis of the unmetamorphosed amphibian.
Assuntos
Endorfinas/análise , Encefalinas/análise , Adeno-Hipófise/citologia , Ambystoma mexicanum , Animais , Anticorpos , Reações Cruzadas , Dinorfinas/análise , Encefalina Leucina/análise , Encefalina Metionina/análise , Imunofluorescência , Imuno-Histoquímica , Fibras Nervosas/ultraestrutura , Adeno-Hipófise/anatomia & histologia , beta-Endorfina/análiseRESUMO
There is evidence for the existence of a descending pain suppression system, but also there are data supporting the hypothesis for the modulation of pain at higher central nervous system levels. In the present study we give evidence for a possible ascending pain modulation pathway which involves the dorsal raphe (DR), the centralis lateralis nucleus (CL) of the thalamus and the medial prefrontal cortex (PFCx). Urethane-anesthetized rats were used. Simultaneous single unit recordings were done in the CL and PFCx regions under noxious and DR stimulations. Cells responding to both types of stimuli exhibit duration responses directly related to the duration of the stimuli. Thus, from our results we conclude a DR influence upon CL and PFCx structures that are involved in the coding of nociceptive information. A possible route for an ascending pain modulation path is proposed.
Assuntos
Lobo Frontal/fisiopatologia , Dor/fisiopatologia , Núcleos da Rafe/fisiopatologia , Núcleos Talâmicos/fisiopatologia , Potenciais de Ação , Animais , Potenciais Evocados , Vias Neurais/fisiologia , Ratos , Ratos EndogâmicosRESUMO
We report the effects exerted by the cortex upon the intralaminar thalamic nucleic, as revealed by reversible blockade of the cortex with spreading depression in awake rats. Extracellular recordings of spontaneous activity were made simultaneously at thalamic and cortical sites. The effect of peripheral receptive field stimulation was to decrease activity of intralaminar thalamic cells. Cortical recordings revealed the cortical regions affected by spreading depression. Two type of cells were identified depending on the changes in their sensorial responses during the cortical spreading depression propagation. The first exhibited a tonic facilitating cortical control when the cortical spreading depression was located at A 8.0 to A 10.0. The second type exhibited a disappearance of the sensorial responses when cortical spreading depression was located at A 4.0 to A 8.0 and also displayed the tonic facilitating control. This indicates that two different identified cortical regions influenced the thalamic activity.