RESUMO
OBJECTIVE: The aim of this study was to examine whether the mu rhythm is also seen in the EEG of alert, undrugged and freely moving rats. The mu rhythm is a salient neocortical synchrony with dominant frequency in the 8-13 Hz band, initially recorded over the parietal and frontal areas of humans and subsequently investigated in monkeys and cats using the term sensorimotor rhythm. In the rat, these oscillations have been described only at single-unit level in the trigeminal system or in the cerebellar hemispheres. METHODS: In order to identify this rhythm, according to the "functional topography" approach, we examined the shape, spectral content, spatial distribution in power spectra, and functional reactivity. Rats were implanted with multiple electrodes along the antero-posterior axes. Monopolar recordings and simultaneous continuous 24-h video were taken in natural dark-light cycles for 6 consecutive days. Brain mappings based on quantitative spectral analysis were made. RESULTS: Spontaneous well-defined 7-12 Hz EEG oscillations were found during immobile wakefulness and REM sleep. Comparable features of these patterns indicated that they are largely analogous to the mu rhythm. CONCLUSIONS: The conservation of mu rhythm in the EEG across mammalian species with different cortical extension suggests that it is functionally important. SIGNIFICANCE: Given the great interest aroused by the properties of the mirror neurons, reflected by the mu rhythm, the detailed characterization of this rhythm in rats during natural life may prove useful in prospective evolutionary studies.
Assuntos
Ritmo alfa , Mapeamento Encefálico , Sono REM/fisiologia , Vigília/fisiologia , Animais , Comportamento Animal , Polissonografia/métodos , Ratos , Ratos Sprague-Dawley , Análise EspectralRESUMO
In chronically-implanted, drug-free, behaving aged Fischer rats, intracerebroventricularly (i.c.v.) and intraperitoneally (i.p.) acetyl-L-carnitine (ALCAR) injections powerfully enhanced motor behavior and head movements aimed at attention and exploratory activity. This effect was dose-dependent and associated with the abolition or substantial reduction of the incidence and duration of the spontaneous EEG generalized hypersynchronous patterns termed High Voltage Spindle (HVS), with an increase in EEG monitored theta activity. The results suggest that ALCAR may stimulate the motivational system and disrupt the hypersynchronous processes by inhibiting the GABAergic thalamic reticular neurons and/or activating the brain stem cholinergic reticular system (pedunculo pontine tegmental, PPT and laterodorsal tegmental, LDT nuclei).
Assuntos
Acetilcarnitina/farmacologia , Envelhecimento/fisiologia , Envelhecimento/psicologia , Comportamento Animal/efeitos dos fármacos , Nootrópicos/farmacologia , Acetilcarnitina/administração & dosagem , Animais , Nível de Alerta/efeitos dos fármacos , Atenção/efeitos dos fármacos , Relação Dose-Resposta a Droga , Implantes de Medicamento , Eletroencefalografia/efeitos dos fármacos , Eletrofisiologia , Comportamento Exploratório/efeitos dos fármacos , Movimentos da Cabeça/efeitos dos fármacos , Injeções Intraperitoneais , Injeções Intraventriculares , Masculino , Atividade Motora/efeitos dos fármacos , Nootrópicos/administração & dosagem , Ratos , Ratos Endogâmicos F344RESUMO
The extrathalamic relay from the brainstem reticular formation to the cerebral cortex in the basal forebrain has been thought to be constituted predominantly, if not exclusively, by cholinergic neurons. In contrast, the septohippocampal projection has been shown to contain an important contingent of gamma-aminobutyric acid (GABA)ergic neurons. In the present study, we investigated whether GABAergic neurons also contribute to the projection from the basal forebrain to neocortical regions, including the mesocortex (limbic) and the isocortex in the rat. For this purpose, retrograde transport of cholera toxin (CT) was examined from the medial prefrontal cortex for the mesocortex and from the parietal cortex for the isocortex and was combined with dual-immunohistochemical staining for either choline acetyltransferase (ChAT) or glutamic acid decarboxylase (GAD) in adjacent series of sections. Retrogradely labelled GAD+ neurons were codistributed with retrogradely labelled ChAT+ neurons through the basal forebrain from both the prefrontal and the parietal cortex, suggesting parallel, widespread cortical projections. The GAD+ cortically projecting cells were similar in size to the ChAT+ cells, thereby indicating that they comprise a contingent of the magnocellular basal cell complex. The proportions of retrogradely labelled neurons that were GAD+ (approximately one-third) were equal to or greater than those that were ChAT+ from both the prefrontal cortex and the parietal cortex. In addition, the total of GAD+ and ChAT+ neurons did not account for the total number of cortically projecting cells, indicating that another equivalent proportion of chemically unidentified noncholinergic neurons also contributes to the basalocortical projection. Accordingly, as in the allocortex, GABAergic, cholinergic, and other unidentified noncholinergic neurons may have the capacity to modulate activity in the mesocortex (limbic) and the isocortex through parallel, widespread projections.
Assuntos
Sistema Nervoso Autônomo/fisiologia , Córtex Cerebral/fisiologia , Neurônios/fisiologia , Sistema Nervoso Parassimpático/fisiologia , Prosencéfalo/fisiologia , Ácido gama-Aminobutírico/fisiologia , Animais , Córtex Cerebral/citologia , Toxina da Cólera , Colina O-Acetiltransferase/metabolismo , Glutamato Descarboxilase/metabolismo , Imuno-Histoquímica , Masculino , Vias Neurais/citologia , Vias Neurais/fisiologia , Sistema Nervoso Parassimpático/citologia , Lobo Parietal/citologia , Lobo Parietal/fisiologia , Córtex Pré-Frontal/citologia , Córtex Pré-Frontal/fisiologia , Prosencéfalo/citologia , Ratos , Ratos WistarRESUMO
The sleep-inducing properties of a new benzodiazepine hypnotic (quazepam--SCH 16134) were evaluated in cats with transection at different levels of the brain stem structure. Effects observed after administration of doses ranging from 0.12 and 1 mg/kg given intravenously were compared with those of pentobarbital. In the encéphale isolé small doses of quazepam induced or increased the synchronized periods. The desynchronized electroencephalogram (EEG) pattern of midpontine pretrigeminal preparations was not modified by these small doses. Only larger doses induced a fast neocortical activity of high amplitude. In midpontine pretrigeminal hemisection the synchronization occurred exclusively or predominantly in the hemisphere contralateral to the lesion. In the cerveau isolé, quazepam did not influence the typical synchronized EEG pattern. The arousal threshold after mesencephalic and physiological stimulation was raised only in encéphale isolé animals. Pentobarbital provoked sustained synchronization in all preparations with a pattern quite different from that of the benzodiazepine. These results suggest that quazepam may act through facilitation of the EEG-synchronizing mechanisms localized in the lower brain stem which are involved in physiological EEG-synchronizing and sleep-inducing processes.
Assuntos
Ansiolíticos , Benzodiazepinas/farmacologia , Sono/efeitos dos fármacos , Estimulação Acústica , Animais , Gatos , Sincronização Cortical , Estado de Descerebração/fisiopatologia , Relação Dose-Resposta a Droga , Estimulação Elétrica , Eletroencefalografia , Feminino , Hipnóticos e Sedativos/farmacologia , Masculino , Pentobarbital/farmacologiaRESUMO
It is well known that the electroencephalogram of the cat in the early stages of slow wave sleep is mainly characterized by rhythmic wave activity at 7-14 Hz, termed spindles, which recur periodically with a slow rhythm of 0.1-0.2 Hz. From early stimulation, decortication and transection studies (see Ref. 14), spindle oscillations were thought to originate in the thalamus. The search for the anatomical substrate of thalamic spindling, however, moved from medial (intralaminar nuclei) to lateral thalamic nuclei, and recently focused on the extreme shell-shaped collection of GABA-ergic cells, the nucleus reticularis thalami. This proposition was based on its structural, hodological, and physiological aspects. There is accumulating evidence that the nucleus reticularis may act as a conditional pacemaker, synchronizing the activity of cortically projecting thalamic neurons. The introduction of glutamate analogues with excitotoxic properties such as ibotenic acid provided the opportunity of studying the immediate effects of chemical excitation of this nucleus on synchronized electroencephalographic activity. We found that, in cats, spindle density was dramatically increased following infusion of ibotenic acid into the rostral pole of the nucleus, supporting the role of this sector in spindle-related rhythmicity.
Assuntos
Eletroencefalografia/efeitos dos fármacos , Ácido Ibotênico/farmacologia , Núcleos Talâmicos , Animais , Gatos , Eletromiografia/efeitos dos fármacos , Ácido Ibotênico/administração & dosagem , Microinjeções , Sono REM/fisiologiaRESUMO
The excitotoxin ibotenic acid (1.2-2.6 microliters of 50 micrograms/microliters) was injected bilaterally into the thalamic centralis lateralis nucleus of chronically implanted cats in order to study the effects of tonic excitation followed by destruction of perikarya on the sleep-waking cycle and its electrographic correlates. Ibotenate injections were performed under mild ketamine anaesthesia. Immediately afterwards, the animals showed behavioural arousal accompanied first by ocular nystagmiform movements and then by pontogeniculooccipital waves. By 6-10 h post-injection, the numbers of rapid eye movement sleep episodes, but not their duration, increased compared to the preinjection control period. The injection sites were histologically confirmed using conventional Thionin stains. Additional control was provided by retrograde transport of wheat-germ agglutinin conjugated with horseradish peroxidase. The present results suggest that a population of neurons important for ocular saccades, pontogeniculooccipital waves, and the state of desynchronized sleep is present in the internal medullary lamina, in particular in the centralis lateralis nuclei.
Assuntos
Movimentos Oculares/efeitos dos fármacos , Ácido Ibotênico/farmacologia , Sono REM/fisiologia , Núcleos Talâmicos/fisiologia , Animais , Transporte Axonal , Gatos , Eletroencefalografia , Eletromiografia , Eletroculografia , Corpos Geniculados/efeitos dos fármacos , Corpos Geniculados/fisiologia , Peroxidase do Rábano Silvestre , Ácido Ibotênico/administração & dosagem , Microinjeções , Músculos do Pescoço/fisiologia , Sono REM/efeitos dos fármacos , Núcleos Talâmicos/efeitos dos fármacos , Tálamo/anatomia & histologia , Tálamo/fisiologia , Fatores de Tempo , Conjugado Aglutinina do Germe de Trigo-Peroxidase do Rábano Silvestre , Aglutininas do Germe de TrigoRESUMO
The present study examined projections of GABAergic and cholinergic neurons from the basal forebrain and preoptic-anterior hypothalamus to the "intermediate" part of the mediodorsal nucleus of the thalamus. Retrograde transport from this region of the mediodorsal nucleus was investigated using horseradish peroxidase-conjugated wheatgerm agglutinin in combination with peroxidase-antiperoxidase immunohistochemical staining for glutamic acid decarboxylase and choline acetyltransferase. A relatively large number of retrogradely-labelled glutamic acid decarboxylase-positive neurons are located in the basal forebrain, amounting to more than 7% of the total population of glutamic acid decarboxylase-positive cells in this region. Moreover, retrogradely-labelled choline acetyltransferase-positive cells are interspersed among glutamic acid decarboxylase-positive neurons, accounting for about 6% of the total choline acetyltransferase-positive cell population in the basal forebrain. The glutamic acid decarboxylase-positive and choline acetyltransferase-positive retrogradely-labelled neurons are distributed throughout several regions of the basal forebrain, including the medial septum, the diagonal band of Broca, the magnocellular preoptic nucleus, the substantia innominata pars anterior, the substantia innominata pars posterior, and the globus pallidus where only a few retrogradely-labelled neurons were seen. The choline acetyltransferase-positive mediodorsal-projecting neurons are morphologically different from the choline acetyltransferase-positive neurons in the basal forebrain, suggesting that those projecting to the mediodorsal nucleus are a small proportion of the cholinergic neuronal population in the basal forebrain. In the preoptic-anterior hypothalamus, many retrogradely-labelled glutamic acid decarboxylase-positive cells were found, amounting to more than 7% of the total population of glutamic acid decarboxylase-positive cells in this region. These retrogradely-labelled glutamic acid decarboxylase-positive neurons are distributed throughout the preoptic-anterior hypothalamus in a continuous line with those in the basal forebrain, including the lateral preoptic area, the medial preoptic area, the bed nucleus of the stria terminalis, and the anterior and dorsal hypothalamic areas. The highest percentage of mediodorsal-projecting GABAergic neurons is in the anterior lateral hypothalamus where more than 25% of the total population of glutamic acid decarboxylase-positive cells project to the mediodorsal nucleus of the thalamus. Overall, of the large population of retrogradely-labelled neurons in the basal forebrain and preoptic-anterior hypothalamus, a significant proportion are glutamic acid decarboxylase-positive neurons (> 60% in the basal forebrain and > 30% in the preoptic-anterior hypothalamus), while the choline acetyltransferase-positive neurons amount to a smaller percentage of the neurons projecting to the mediodorsal nucleus (< 13% in the basal forebrain and < 2% in the preoptic-anterior hypothalamus). These results provide anatomical evidence of direct GABAergic projections from the basal forebrain and preoptic-anterior hypothalamic regions to the "intermediate" part of the mediodorsal nucleus in the cat. This GABAergic projection field could be the direct pathway by which the basal forebrain directly modulates thalamic excitability and may also be involved in mechanisms modulating electroencephalographic synchronization and sleep through the "intermediate" mediodorsal nucleus.
Assuntos
Núcleo Hipotalâmico Anterior/fisiologia , Fibras Colinérgicas/fisiologia , Área Pré-Óptica/fisiologia , Prosencéfalo/fisiologia , Transmissão Sináptica/fisiologia , Núcleos Talâmicos/fisiologia , Ácido gama-Aminobutírico/fisiologia , Animais , Núcleo Hipotalâmico Anterior/citologia , Mapeamento Encefálico , Gatos , Colina O-Acetiltransferase/metabolismo , Feminino , Glutamato Descarboxilase/metabolismo , Masculino , Sondas Moleculares , Neurônios/fisiologia , Área Pré-Óptica/citologia , Prosencéfalo/citologia , Conjugado Aglutinina do Germe de Trigo-Peroxidase do Rábano SilvestreRESUMO
Recent data suggest that interleukin-1-induced enhancement of non-rapid eye movement sleep is mediated, in part, by the serotonergic system. To determine if sleep changes induced by interleukin-1 are mediated by a specific serotonergic receptor subtype, we evaluated interleukin-1 effects on sleep in rats pretreated with the 5-hydroxytryptamine (serotonin)-2 receptor antagonist ritanserin. Ritanserin (0.63 mg/kg, intraperitoneally) by itself did not alter sleep-wake behavior, although it did reduce cortical brain temperature. Interleukin-1 (5 ng, intracerebroventricularly) enhanced non-rapid eye movement sleep, suppressed rapid eye movement sleep, and induced a moderate febrile response. Pretreatment with ritanserin completely blocked the febrile response to interleukin-1 and abolished the interleukin-1-induced enhancement in non-rapid eye movement sleep that occurred during postinjection hours 3-4, without altering interleukin-1 effects on rapid eye movement sleep. The present data suggest that serotonin may partially mediate interleukin-1 effects on sleep by interacting with 5-hydroxytryptamine (serotonin)-2 receptors. These results also suggest that interactions between the serotonergic system and interleukin-1 may be important in regulating sleep-wake behavior.
Assuntos
Interleucina-1/farmacologia , Receptores de Serotonina/efeitos dos fármacos , Ritanserina/farmacologia , Antagonistas da Serotonina/farmacologia , Sono/efeitos dos fármacos , Animais , Temperatura Corporal/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Masculino , Ratos , Ratos Sprague-Dawley , Sono/fisiologiaRESUMO
The precise role of serotonin (5-hydroxytryptamine) in the regulation of sleep is not fully understood. To further clarify this role for 5-hydroxytryptamine, the 5-hydroxytryptamine precursors L-tryptophan (40 and 80 mg/kg) and L-5-hydroxytryptophan (25-, 50-, 75-, 100 mg/kg) were injected intraperitoneally into freely behaving rats 15 min prior to dark onset, and subsequent effects on sleep-wake activity and cortical brain temperature were determined. L-5-hydroxytryptophan, but not L-tryptophan, induced dose-dependent changes in sleep-wake activity. During the 12-h dark period, non-rapid eye movement sleep was inhibited in post-injection hours 1-2 by the two lowest L-5-hydroxytryptophan doses tested, while the two highest doses induced a delayed increase in non-rapid eye movement sleep in post-injection hours 3-12. These highest doses inhibited non-rapid eye movement sleep during the subsequent 12-h light period. The finding that L-5-hydroxytryptophan, but not L-tryptophan, induced a dose-dependent and long-lasting decrease in cortical brain temperature regardless of whether or not non-rapid eye movement sleep was suppressed or enhanced contributes to a growing list of conditions showing that sleep-wake activity and thermoregulation, although normally tightly coupled, may be dissociated. The initial non-rapid eye movement sleep inhibition observed following low doses of L-5-hydroxytryptophan may be attributable to increased serotonergic activity since 5-hydroxytryptamine may promote wakefulness per se, whereas the delayed non-rapid eye movement sleep enhancement after higher doses may be due to the induction by 5-hydroxytryptamine of sleep-inducing factor(s), as previously hypothesized. The period of non-rapid eye movement sleep inhibition beginning 12 h after administration of L-5-hydroxytryptophan doses that increase non-rapid eye movement sleep is characteristic of physiological manipulations in which non-rapid eye movement sleep is enhanced. The results of the present study suggest that the complex effects of 5-HT on sleep depend on the degree and time course of activation of the serotonergic system such that 5-HT may directly inhibit sleep, yet induce a cascade of physiological processes that enhance subsequent sleep.
Assuntos
Temperatura Corporal/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Serotonina/farmacologia , Sono REM/efeitos dos fármacos , Triptofano/farmacologia , Animais , Comportamento Animal/efeitos dos fármacos , Regulação da Temperatura Corporal/efeitos dos fármacos , Encéfalo/fisiologia , Eletroencefalografia/efeitos dos fármacos , Masculino , Ratos , Ratos Sprague-Dawley , Vigília/efeitos dos fármacosRESUMO
Changes in the serotonergic system in the posterior hypothalamus of freely moving rats were related to sleep and wakefulness using in vivo voltammetry (with carbon fiber microelectrodes) and polygraphic recordings. By using an optoelectronic telemetry system for the voltammetric signals, electrical cross-talk between the two settings was avoided and simultaneous neurochemical and electro-physiological recordings could be made so that a detailed time course of events could be obtained. Extracellular levels of the serotonin metabolite, 5-hydroxy-indoleacetic acid, measured every 2 min, increased with wakefulness and decreased with sleep: levels were significantly lower during desynchronized sleep than slow wave sleep. In vivo voltammetry associated with the optoelectronic telemetry system appears to be a useful tool for studying the relationship between neurochemical changes and electrophysiological events.
Assuntos
Hipotálamo Posterior/fisiologia , Serotonina/fisiologia , Sono/fisiologia , Vigília/fisiologia , Animais , Comportamento Animal/fisiologia , Química Encefálica/fisiologia , Eletroencefalografia , Eletrofisiologia , Espaço Extracelular/metabolismo , Histocitoquímica , Ácido Hidroxi-Indolacético/metabolismo , Masculino , Polissonografia , Ratos , Sono REM/fisiologia , TelemetriaRESUMO
The activity of the serotonergic system varies in phase with the sleep-wake cycle, which is associated with changes in several physiological functions, including electroencephalographic activity, brain temperature, and locomotion. The aim of the present study was to clarify which of these parameters correlates better with serotonergic activity in spontaneous conditions. Voltammetric recordings by telemetry of serotonergic metabolism in the medial preoptic area and polygraphic recordings of sleep-wake activity (by means of electroencephalographic delta band, brain cortical temperature and neck electromyographic activity recordings) were simultaneously performed in freely moving rats. Univariate analyses of variance revealed that each variable under investigation was statistically correlated with serotonergic metabolism. When the variables were entered into the model simultaneously, both partial correlation and step-wise multiple regression analyses indicated that the highest correlation exists between serotonergic metabolism and brain cortical temperature. The present data show that serotonergic activity in the medial preoptic area is closely linked to physiological changes in brain temperature.
Assuntos
Temperatura Corporal/fisiologia , Córtex Cerebral/fisiologia , Hipotálamo/fisiologia , Serotonina/fisiologia , Sono/fisiologia , Vigília/fisiologia , Análise de Variância , Animais , Ritmo Delta , Eletroencefalografia , Eletromiografia , Masculino , Atividade Motora , Músculo Esquelético/inervação , Músculo Esquelético/fisiologia , Ratos , TelemetriaRESUMO
Somatosensory cortical neurons were intracellularly and extracellularly recorded in cats encéphale isolé, and after acute lesions of midthalamic nuclei or after chronic hemisection of the brain stem at the pretrigeminal level. Intracellular recordings showed postsynaptic facilitatory and inhibitory effects at very low latency by stimulating both the mesencephalic (MRF) and bulbar reticular formation (BRF). Inhibitory effects dominated by stimulating the BRF. Neither midthalamic lesions nor pretrigeminal hemisection changed the quality of latency of postsynaptic responses. Extracellular recordings revealed long-latency inhibition of discharge following MRF stimulation after midthalamic lesion. In these experimental conditions long-latency BRF effects were abolished. No differences were found in responses of pyramidal tract (PT) or non-PT neurons during BRF and MRF stimulation. The results are discussed on the basis of a possible extrathalamic differential reticular control, from caudal and rostral brain stem, of somatosensory cortical neurons.
Assuntos
Mesencéfalo/fisiologia , Neurônios/fisiologia , Formação Reticular/fisiologia , Córtex Somatossensorial/fisiologia , Animais , Gatos , Eletroencefalografia , Inibição Neural , Vias Neurais/fisiologia , Tempo de Reação , Núcleos Talâmicos/fisiologiaRESUMO
Male Sprague-Dawley rats injected (i.p.) at 1500h with L-acetyl-carnitine in doses of 10, 30 or 90 mg/kg exhibited a notable increase in their pineal and serum melatonin content 1 hr later. Likewise, L-acetyl-carnitine administered in the same dose range induced a significant increase of pineal and serum melatonin content in rats treated at 0100h, following exposure of 30 min to bright white light to suppress endogenous melatonin. Under in vitro experimental conditions, however, 60 min of coincubation of isolated rat pineal glands with L-acetyl-carnitine (10(-5) M) did not result in an elevation in melatonin accumulated in the incubation medium. These results demonstrate that, in vivo, L-acetyl-carnitine can exert a modulatory action on synthesis and release of melatonin, possibly by modifying noradrenergic transmission and signal transduction in the pineal gland.
Assuntos
Acetilcarnitina/farmacologia , Melatonina/sangue , Glândula Pineal/efeitos dos fármacos , Animais , Técnicas de Cultura , Relação Dose-Resposta a Droga , Masculino , Glândula Pineal/fisiologia , Ratos , Ratos EndogâmicosRESUMO
Voltage-dependent Ca2+ channels in adult rat sensory neurones were studied as far as their characterization and nimodipine effects are concerned, using patch-clamp whole-cell technique. Low-voltage activated (LVA) Ca2+ currents were identified according to activation and inactivation kinetics and sensitivity to amiloride. Nimodipine (10 nM) caused a decrease in LVA Ca2+ current amplitude (-40% +/- 2.2 s.e.m., n = 11 out of 30 with LVA Ca2+ currents). Conversely, in 6 neurones out of 30 nimodipine increased the Ca2+ current amplitude (+ 10% +/- 2). In some unaffected neurones (n = 5) nimodipine was also tested at higher concentrations (up to 5 microM) without any appreciable effect. In conclusion, nimodipine was partly able to block LVA calcium channels even at nanomolar concentrations. Supposing nimodipine acts directly on the channel, it can be assumed that there may be different types of LVA calcium channels in sensory neurones.
Assuntos
Canais de Cálcio/efeitos dos fármacos , Neurônios Aferentes/efeitos dos fármacos , Nimodipina/farmacologia , Animais , Cálcio/metabolismo , Canais de Cálcio/classificação , Células Cultivadas , Gânglios Espinais/citologia , Potenciais da Membrana , Neurônios Aferentes/fisiologia , Ratos , Ratos WistarRESUMO
To study the role of muscarinic receptor subtypes in sleep control, methoctramine (25, 50, 75 micrograms), a highly selective M2 antagonist, was injected intra-cerebroventricularly into freely moving rats. Methoctramine induced a dose-dependent increase in desynchronized sleep (DS) latency (from 62.7 +/- 10 min following saline to 122.4 +/- 13.8 min with the lowest dose) and a 75% decrease in the amount of DS in 6 h recordings. 4DAMP (a M3/M1 selective antagonist) did not significantly change DS latency and percentage time, but it reduced wakefulness (from 38 +/- 2.8% following saline to 25.3 +/- 3.7% with a dose of 2.5), and increased slow wave sleep. The results suggest that M2 muscarinic receptors play a selective role in DS physiology.
Assuntos
Ventrículos Cerebrais/fisiologia , Diaminas/farmacologia , Piperidinas/farmacologia , Receptores Muscarínicos/fisiologia , Sono/efeitos dos fármacos , Simpatolíticos/farmacologia , Vigília/efeitos dos fármacos , Animais , Ventrículos Cerebrais/efeitos dos fármacos , Diaminas/administração & dosagem , Relação Dose-Resposta a Droga , Injeções Intraventriculares , Masculino , Piperidinas/administração & dosagem , Ratos , Ratos Endogâmicos , Receptores Muscarínicos/efeitos dos fármacos , Valores de ReferênciaRESUMO
P-fluoro-hexahydro-sila-difenidol hydrochloride (p-F-HHSiD) (15, 30 micrograms) and pirenzepine (7.5, 15, 30 micrograms), which are highly selective M3 and M1 muscarinic antagonists, respectively, were injected intracerebroventricularly into freely moving rats. p-F-HHSiD (30 micrograms) reduced wakefulness (W) (from 34.7 +/- 3.1 to 24.9 +/- 1.3 min) and increased slow wave sleep (SWS) (from 56.7 +/- 2.4 to 67.2 +/- 1.5 min); however, it did not modify desynchronized sleep (DS) latency and percentage in 6 h recordings. W and SWS were not affected by pirenzepine (7.5, 15, 30 micrograms) which decreased significantly DS amount but left unaffected DS latency. The results suggest that each muscarinic receptor subtype may induce different and specific changes in sleep phases and cortical desynchronization processes.
Assuntos
Piperidinas/farmacologia , Pirenzepina/farmacologia , Receptores Muscarínicos/fisiologia , Sono/fisiologia , Animais , Injeções Intraventriculares , Masculino , Antagonistas Muscarínicos , Ratos , Sono/efeitos dos fármacos , Vigília/efeitos dos fármacosRESUMO
To clarify which muscarinic receptor subtype(s) mediate changes in sleep and cortical temperature (Tcort) induced by carbachol microinjections into the medial preoptic area (MPA), pirenzepine, tripitramine and +/- p < > -fluorohexahydro-sila-difenidol (p-F-HHSiD), which are highly selective muscarinic M1, M2 and M3 antagonists, respectively, were microinjected into the MPA of rats. Whereas pirenzepine (3.45 and 7.08 nmol) and p-F-HHSiD (3.90 and 7.80 nmol) were without effect, tripitramine (0.67 and 3.37 nmol) enhanced wakefulness, decreased slow wave and desynchronized sleep, and raised Tcort with the higher dose. The data suggest that in the MPA only M2 muscarinic subtypes may be functionally important in mediating the cholinergic effects on sleep and thermoregulation.
Assuntos
Antagonistas Muscarínicos/farmacologia , Área Pré-Óptica/fisiologia , Receptores Muscarínicos/fisiologia , Sono/fisiologia , Vigília/fisiologia , Animais , Benzodiazepinas/administração & dosagem , Benzodiazepinas/farmacologia , Regulação da Temperatura Corporal/efeitos dos fármacos , Masculino , Microinjeções , Piperidinas/administração & dosagem , Piperidinas/farmacologia , Pirenzepina/administração & dosagem , Pirenzepina/farmacologia , Área Pré-Óptica/anatomia & histologia , Ratos , Sono REM/efeitos dos fármacosRESUMO
The possibility of area-specific changes in binding sites for CGRP in response to stress was studied in cat CNS after repeated sleep-deprivation and restriction of movement. Brain sections were obtained from a cat placed under stressful conditions for 2 h the 1st day, 6 h the 2nd day and 24 h the 3rd day. Changes in CGRP binding sites were evaluated by an in vitro autoradiographic technique with 125I-Tyr-rat-CGRP as a ligand. The autoradiograms were then compared with those of control animals. The results show decreased labelling in the cortex prefrontalis and pyriformis and in some basal ganglia (n. caudatus, claustrum, n. entopedencularis). Increased CGRP binding site densities were seen in areas involved in the integration of sensory information, in the control of endocrine secretion and in those that participate in sleep-walking cycles. These changes in CGRP binding in selective CNS areas following stress suggests that CGRP plays a role in processes of adaptation.
Assuntos
Encéfalo/metabolismo , Peptídeo Relacionado com Gene de Calcitonina/metabolismo , Receptores de Superfície Celular/metabolismo , Estresse Fisiológico/metabolismo , Animais , Gatos , Receptores da CalcitoninaRESUMO
Calcitonin (CT) binding site distribution has been studied in the cat CNS. The autoradiographic analyses of [125I]-eelCT (ECT) binding showed high density of silver grains in the mesencephalic PAG, in the raphe nuclei and in the dorsal horns, laminae I, IV, V, and VI, where ECT may act to inhibit nociceptive transmission. Other binding-rich areas included the caudatus, the amygdala, the hypothalamus, the substantia nigra, the locus coeruleus and the formatio reticularis mesencephalica. Medium to low density was seen, amongst other areas in the cortex piriformis, the hippocampus, the medial and intralaminar thalamus and the tractus spino-thalamicus. ECT binding site distribution revealed essentially homologous locations in the cat and rat CNS. At difference, the presence of binding in the piriform cortex and in discrete thalamic nuclei suggests a widespread involvement of ECT in a variety of central functions in addition to what already demonstrated.
Assuntos
Encéfalo/fisiologia , Sistema Nervoso Central/análise , Receptores de Superfície Celular/análise , Animais , Autorradiografia , Calcitonina/fisiologia , Gatos , Receptores da CalcitoninaRESUMO
Among the various functions of sleep, one is particularly significant for our mental life: that of producing dreams. This specifically human experience, which takes place only during sleep, is closely related with neurophysiological events. The coincidence between mental and biological events raises a complex epistemological question concerning the close relationship between dreams, viewed as a subjective experience and sleep, viewed as a vegetative experience which is possible to define from a behavioural, electrical, neurochemical and neurobiological viewpoint. In this presentation, the author criticizes Hobson and McCarley's internal generator theory, according to which the pons activates the limbic structures responsible for the recovery of memory in dreams, on account of physiological and psychological reasons. The author puts forward a cognitive hypothesis, which considers dreams as a symbolic process of elaborating, interpreting and reorganizing in narrative sequences all the material accumulated in the memory during waking hours. The author proposes, therefore, a psychoanalytical model of dreaming, in which dreams constitute a way of representing the individual's inner world with internal objects related with one another and with the Self.