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1.
Biol Psychiatry ; 29(3): 204-10, 1991 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-1673063

RESUMEN

Nonaffective psychotic symptoms are heterogeneous and probably caused by mixed biopathology. A preliminary investigative tool to study pituitary dopamine activity, the prolactin response to submaximal stimulation by thyrotropin-releasing hormone (TRH) (mini-TRH test) was correlated in 20 subjects with nonaffective psychoses to positive psychotic symptoms as assessed by the Comprehensive Psychiatric Rating Scale psychosis subscale. A significant positive correlation was observed between the response and ratings of nonparanoid symptoms, especially nonparanoid delusions and disrupted thoughts. Because, in addition to pituitary dopamine activity, there is evidence to suggest that the response reflects extrapituitary dopamine activity as well, the results extend the evidence that nonparanoid acute productive psychotic symptoms may be associated with hypoactivity rather than with hyperactivity of brain dopaminergic systems.


Asunto(s)
Prolactina/sangre , Trastornos Psicóticos/sangre , Hormona Liberadora de Tirotropina , Adulto , Antipsicóticos/efectos adversos , Antipsicóticos/uso terapéutico , Femenino , Humanos , Masculino , Escalas de Valoración Psiquiátrica , Trastornos Psicóticos/diagnóstico , Trastornos Psicóticos/psicología , Receptores Dopaminérgicos/efectos de los fármacos , Esquizofrenia/sangre , Esquizofrenia/diagnóstico , Psicología del Esquizofrénico , Síndrome de Abstinencia a Sustancias/sangre , Síndrome de Abstinencia a Sustancias/diagnóstico , Síndrome de Abstinencia a Sustancias/psicología
2.
J Clin Psychiatry ; 62(6): 448-52, 2001 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-11465522

RESUMEN

BACKGROUND: Although case reports and open studies have reported augmentation with buspirone to be beneficial in the treatment of depression refractory to treatment with a selective serotonin reuptake inhibitor (SSRI), a recently published randomized, placebo-controlled, double-blind study failed to show superiority of buspirone over placebo in this respect. METHOD: One hundred two outpatients who fulfilled DSM-IV criteria for a major depressive episode and who had failed to respond to a minimum of 6 weeks of treatment with either fluoxetine or citalopram were included in this double-blind, randomized, placebo-controlled study. After a single-blind placebo wash-in period of 2 weeks while continuing their SSRI, the patients were randomly assigned to adjunctive treatment with either buspirone, 10 to 30 mg b.i.d., or placebo for 6 weeks. Patients were assessed using the Montgomery-Asberg Depression Rating Scale (MADRS), the Clinical Global Impressions scale (CGI), and visual analogue scales. RESULTS: After the first week of double-blind treatment, there was a significantly greater reduction in MADRS score (p = .034) in the buspirone group as compared with placebo. At endpoint, there was no significant difference between treatment groups as a whole, although patients with initially high MADRS scores (> 30) showed a significantly greater reduction in MADRS score (p = .026) in the buspirone group as compared with placebo. CONCLUSION: Patients with severe depressive symptoms may benefit from augmentation with buspirone. It cannot be excluded that augmentation with buspirone may speed up the antidepressive response of patients refractory to treatment with fluoxetine or citalopram.


Asunto(s)
Buspirona/uso terapéutico , Trastorno Depresivo/tratamiento farmacológico , Inhibidores Selectivos de la Recaptación de Serotonina/uso terapéutico , Agonistas de Receptores de Serotonina/uso terapéutico , Adulto , Anciano , Atención Ambulatoria , Buspirona/efectos adversos , Citalopram/efectos adversos , Citalopram/uso terapéutico , Trastorno Depresivo/diagnóstico , Trastorno Depresivo/psicología , Método Doble Ciego , Esquema de Medicación , Quimioterapia Combinada , Femenino , Finlandia , Fluoxetina/efectos adversos , Fluoxetina/uso terapéutico , Humanos , Masculino , Persona de Mediana Edad , Pacientes Desistentes del Tratamiento , Placebos , Escalas de Valoración Psiquiátrica/estadística & datos numéricos , Agonistas de Receptores de Serotonina/efectos adversos , Inhibidores Selectivos de la Recaptación de Serotonina/efectos adversos , Índice de Severidad de la Enfermedad , Método Simple Ciego , Resultado del Tratamiento
3.
Schizophr Res ; 26(2-3): 103-5, 1997 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-9323339

RESUMEN

The phospholipase-A2 activity in plasma from 62 psychiatric patients admitted in an acute state to psychiatric hospital was determined by a fluorometric assay and compared to that of age- and sex-matched controls. Contrary to earlier findings, no significant differences were found between patients and controls.


Asunto(s)
Fosfolipasas A/metabolismo , Esquizofrenia/enzimología , Enfermedad Aguda , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Fosfolipasas A2 , Escalas de Valoración Psiquiátrica , Esquizofrenia/diagnóstico
4.
Schizophr Res ; 12(1): 29-34, 1994 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-8018583

RESUMEN

Plasma levels of interleukin (IL)-1 beta and IL-6 were measured in 60 acutely hospitalized psychiatric patients and in 60 healthy controls by enzyme-linked immunosorbent assay (ELISA). Almost no IL-6 was detected in the plasma of the patients or controls. The mean level of IL-1 beta was found to be significantly higher in schizophrenic patients than in their corresponding controls (P = 0.03). The acute schizophrenics, but not the group of chronic schizophrenics, contributed to this increase. No correlation with age, duration of illness or overt psychopathology was found. The neuroleptic medication did not prove to have a significant effect on the plasma IL-1 beta levels. There was no difference between non-psychotic affective disorder patients (N = 17) and the controls.


Asunto(s)
Interleucina-1/sangre , Interleucina-6/sangre , Trastornos del Humor/inmunología , Trastornos Psicóticos/inmunología , Esquizofrenia/inmunología , Psicología del Esquizofrénico , Adulto , Enfermedad Crónica , Femenino , Humanos , Masculino , Persona de Mediana Edad , Trastornos del Humor/diagnóstico , Trastornos del Humor/psicología , Trastornos Psicóticos/diagnóstico , Trastornos Psicóticos/psicología , Valores de Referencia , Esquizofrenia/diagnóstico
5.
Eur Neuropsychopharmacol ; 1(4): 535-40, 1991 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-1688013

RESUMEN

Plasma concentrations of remoxipride and haloperidol as well as prolactin (PRL) were determined in 20 patients with acute symptoms of schizophrenia. Ten patients received remoxipride and ten patients haloperidol for a period of 6 weeks. A significant linear correlation was found between the plasma level of remoxipride and the dosage applied (P less than 0.02) as well as between the corresponding haloperidol dosage and plasma concentration (P less than 0.05). In both patient groups a significant reduction in psychopathology was observed during the trial period (P less than 0.001). In the haloperidol group this was associated with a clearcut elevation of plasma PRL, whereas in the remoxipride group after an initial rise for 4 weeks, the mean PRL level returned to baseline at the end of the study.


Asunto(s)
Antipsicóticos/sangre , Benzamidas/sangre , Haloperidol/sangre , Prolactina/sangre , Esquizofrenia/tratamiento farmacológico , Adolescente , Adulto , Antipsicóticos/uso terapéutico , Benzamidas/uso terapéutico , Método Doble Ciego , Femenino , Haloperidol/uso terapéutico , Humanos , Masculino , Persona de Mediana Edad , Escalas de Valoración Psiquiátrica , Remoxiprida , Psicología del Esquizofrénico
6.
J Clin Neurophysiol ; 18(1): 9-13, 2001 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11290933

RESUMEN

The authors studied how clozapine treatment of patients with chronic schizophrenia affects the scalp topographic distribution of different frequency bands on EEG. Twenty-one patients treated with clozapine, in addition to zero to two typical neuroleptics (13 patients were treated with clozapine as the only neuroleptic), were compared with two control groups: one of healthy subjects and another of patients with schizophrenia receiving one to three typical neuroleptics and no clozapine. Significant differences in the EEG topography were seen between the groups: The theta and delta powers and were increased in the clozapine group compared with the two other groups (P < 0.001). Changes were observed over all electrodes, and were most prominent at the frontal, central, and parietal electrode locations. The nonclozapine-treated group of patients and the healthy control group did not differ significantly from each other. These results suggest that the topographic EEG features caused by clozapine are quite specific to it and can be differentiated from those of other neuroleptics.


Asunto(s)
Mapeo Encefálico/métodos , Corteza Cerebral/efectos de los fármacos , Clozapina/farmacología , Agonistas de Dopamina/farmacología , Electroencefalografía/efectos de los fármacos , Esquizofrenia/fisiopatología , Adulto , Anciano , Corteza Cerebral/fisiología , Clozapina/uso terapéutico , Agonistas de Dopamina/uso terapéutico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Cuero Cabelludo/efectos de los fármacos , Cuero Cabelludo/fisiología , Esquizofrenia/tratamiento farmacológico , Estadísticas no Paramétricas
7.
Int Clin Psychopharmacol ; 14(4): 233-8, 1999 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-10468316

RESUMEN

A combination of nefazodone with a conventional neuroleptic would lead to a serotonin (5-HT)2 and D2 receptor blockade resembling that of an atypical neuroleptic, with an additional increase of 5-HT (and noradrenaline) turnover. This may be of benefit in some cases of schizophrenia. In this study, eight patients with schizophrenia with predominantly negative and/or depressive symptoms underwent an open prospective 26-week trial with nefazodone, added to conventional neuroleptics. The total Positive and Negative Syndrome Scale (PANSS) and the Montgomery-Asberg Depression Rating Scale (MADRS) scores (the last observations carried forward, LOCF) significantly (P < 0.05) decreased in these eight patients by a mean of 31% and 63%, respectively, mainly within the first 6 weeks. Positive symptoms, observed in three patients and panic attacks in two patients disappeared entirely. The doses of neuroleptics, stable during the first 6 weeks of the trial, subsequently were able to be decreased by 28%. Extrapyramidal symptoms noticeably improved during the phase of stable neuroleptic dose regimen. Of the three patients who discontinued the trial prematurely (after 14 weeks or more), only one evidenced a nefazodone-related adverse event. Adjunctive nefazodone may be a useful treatment option in this patient population, but additional studies are recommended.


Asunto(s)
Antidepresivos de Segunda Generación/uso terapéutico , Antipsicóticos/uso terapéutico , Esquizofrenia/tratamiento farmacológico , Antagonistas de la Serotonina/uso terapéutico , Triazoles/uso terapéutico , Adolescente , Adulto , Antidepresivos de Segunda Generación/efectos adversos , Antipsicóticos/efectos adversos , Trastorno Depresivo/complicaciones , Trastorno Depresivo/tratamiento farmacológico , Quimioterapia Combinada , Femenino , Humanos , Masculino , Persona de Mediana Edad , Proyectos Piloto , Piperazinas , Estudios Prospectivos , Escalas de Valoración Psiquiátrica , Esquizofrenia/complicaciones , Antagonistas de la Serotonina/efectos adversos , Triazoles/efectos adversos
8.
Int Clin Psychopharmacol ; 9(3): 203-6, 1994 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-7814830

RESUMEN

Fluoxetine, a selective inhibitor of serotonin (5-HT) uptake, was compared with placebo in a randomized double-blind longitudinal trial in 12 healthy volunteers. Sleep polygraphic recordings were performed at home twice before and once after 6 days of medication. After 6 days fluoxetine significantly decreased the amount of rapid eye movement (REM) sleep. The sleep-onset latency and REM latency were increased, but there was no significant increase in the amount of awakenings during night. The relative proportion of stages 2 and 3 increased after fluoxetine administration, although there was no significant change with regard to total amount of slow-wave sleep. Fluoxetine did not induce prominent eye movements during non-rapid eye movement (NREM) sleep in this study. Results of the subjective assessment revealed tendencies of improved sleep and well-being in the fluoxetine group. It is concluded that a comparatively small dose of fluoxetine (20 mg/day) causes the same type of changes in REM sleep which are characteristic of most antidepressive drugs.


Asunto(s)
Electroencefalografía/efectos de los fármacos , Fluoxetina/farmacología , Polisomnografía/efectos de los fármacos , Fases del Sueño/efectos de los fármacos , Adulto , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Femenino , Humanos , Estudios Longitudinales , Masculino , Tiempo de Reacción/efectos de los fármacos , Sueño REM/efectos de los fármacos , Vigilia/efectos de los fármacos
9.
Int Clin Psychopharmacol ; 17(4): 177-84, 2002 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-12131601

RESUMEN

The effect of a single dose of 10 mg olanzapine on healthy volunteers of both sexes was examined using polysomnography and power spectral analysis. The structure and continuity of sleep were unaffected by olanzapine in both sexes. The increase in both actual sleep time and slow wave sleep in females correlated with the increase in theta power, while delta power was not significantly elevated, suggesting that theta power may be a sensitive indicator of changes in sleep. The changes in sleep had the same tendency in men, but they were not significant. The difference between the sexes could not be explained by differences in body mass index. Olanzapine affects sleep probably through 5-HT(2C) receptors. The receptor gene is located on the X-chromosome, inducing an allelic difference between the females and males. This difference may contribute to the different effects of olanzapine on sleep. Olanzapine seems to preserve the normal structure of sleep and increase the amount of slow-wave sleep, which might be of additional benefit in treatment of schizophrenia. The effective clinical dose may be lower for females than males.


Asunto(s)
Antipsicóticos/farmacología , Pirenzepina/análogos & derivados , Pirenzepina/farmacología , Serotoninérgicos/farmacología , Sueño/efectos de los fármacos , Adulto , Antipsicóticos/administración & dosificación , Benzodiazepinas , Electroencefalografía , Femenino , Humanos , Masculino , Olanzapina , Pirenzepina/administración & dosificación , Polisomnografía , Serotoninérgicos/administración & dosificación , Factores Sexuales , Fases del Sueño/efectos de los fármacos , Fases del Sueño/genética
13.
Acta Physiol Scand ; 95(4): 431-40, 1975 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-1211199

RESUMEN

Rubrospinal effects on about 60 extracellularyl recorded gamma-motoneurones were studied in anesthetized cats. All cells were antidromically identified from various muscle nerves. 23 cells were regarded as dynamic as they were activated from a mesencephalic region previously known to influence selectively muscle spindle dynamic sensitivity. The pattern of rubrospinal influence on static fusimotor neurones to different muscles closely followed that previously demonstrated for alpha-motoneurones with pr edominantly excitation of flexor neurones and excitation or inhibition in equal amounts of extensor cells. Dynamic fusimotor neurones were influenced in a strictly reciprocal manner with excitation of flexor cells and inhibition of extensor cells except for a few neurones which could not be reached from nucleur ruber. Evidence was also obtained indicating that the shortest path from nucleus ruber to static fusimotor neurones involves one interneurone.


Asunto(s)
Neuronas Motoras/fisiología , Sistema Nervioso , Vías Nerviosas , Médula Espinal/fisiología , Animales , Axones/fisiología , Gatos , Estimulación Eléctrica , Miembro Posterior/inervación , Mesencéfalo/fisiología , Músculos/inervación , Conducción Nerviosa , Inhibición Neural
14.
J Physiol ; 373: 419-41, 1986 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-3746678

RESUMEN

Experiments were performed on twenty-one cats anaesthetized with alpha-chloralose. The aim of this study was to investigate the reflex effects on triceps surae and plantaris fusimotor neurones elicited by tonic stretch of the contralateral posterior biceps and semitendinosus (p.b.s.t.) and the contralateral triceps surae and plantaris muscles, to compare these effects with the effects evoked by flexion or extension of the intact contralateral hind limb (Appelberg, Hulliger, Johansson & Sojka, 1984) and to clarify the interactions between the reflexes from contralateral and ipsilateral muscles. Activity in fusimotor neurones was studied indirectly by recording from primary muscle spindle afferents of the triceps surae and plantaris muscle. The mean rate of firing and the modulation of the afferent response to sinusoidal extension of the triceps surae and plantaris muscles was determined. Control measurements were made with the ipsilateral p.b.s.t., the contralateral p.b.s.t. and the contralateral triceps and plantaris muscles relaxed. Tests were made with tonic stretch of one of these muscles alone or with two of them simultaneously. With stretch of the contralateral p.b.s.t. ten out of eighty-four primary afferents (11.9%) showed predominantly dynamic reflexes (six out of forty-one in spinalized preparations: 14.6%), twenty-two (26.2%) showed mixed or predominantly static effects (one spinalized: 2.4%) and fifty-two units (61.9%) showed no effect (thirty-four spinalized: 83.0%). The reflex effects could be reproduced by electrical stimulation of the cut contralateral p.b.s.t. nerve either at group II or at group III strength. With stretch of the contralateral triceps and plantaris muscles seventy out of seventy-six (92.1%) primary muscle spindle afferents showed no effect and six (7.9%) mixed or predominantly static reflex effects. In general, the reflex effects were not accompanied by detectable electromyographic (e.m.g.) activity in the ipsilateral triceps and plantaris (recorded with surface or needle electrodes), indicating that the reflexes mainly involved gamma-motoneurones. The difference in efficacy between contralateral flexor (p.b.s.t.) and extensor (triceps and plantaris) muscles seems to be in accordance with the response pattern found with extension or flexion of the intact contralateral hind limb (Appelberg et al. 1984).(ABSTRACT TRUNCATED AT 400 WORDS)


Asunto(s)
Neuronas Motoras gamma/fisiología , Neuronas Motoras/fisiología , Músculos/fisiología , Reflejo de Estiramiento , Reflejo/fisiología , Animales , Gatos , Miembro Anterior , Miembro Posterior , Factores de Tiempo
15.
Artículo en Inglés | MEDLINE | ID: mdl-8499501

RESUMEN

Twelve outpatients with seasonal affective disorder (depression, winter type) were treated by 1 h of bright light exposure for five mornings. The intervention produced a significant reduction in depression scores, but no change was seen in the sleep electroencephalographic variables recorded after light treatment. Significant changes were seen, however, in ratings of subjective sleepiness. The acrophase of the circadian sleepiness rhythm was phase advanced, the mean level of the sleepiness rhythm was diminished, and the mean values of sleepiness scores were reduced at 8 and 10 a.m. This minimal influence of bright light on sleep structure is unlikely to explain the well-documented antidepressant effect.


Asunto(s)
Trastorno Afectivo Estacional/terapia , Sueño REM , Adulto , Atención Ambulatoria , Ritmo Circadiano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Fototerapia , Escalas de Valoración Psiquiátrica , Trastorno Afectivo Estacional/complicaciones , Trastorno Afectivo Estacional/diagnóstico , Trastorno Afectivo Estacional/rehabilitación , Trastornos del Sueño-Vigilia/complicaciones , Trastornos del Sueño-Vigilia/diagnóstico , Trastornos del Sueño-Vigilia/terapia
16.
J Physiol ; 185(1): 160-71, 1966 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-4226252

RESUMEN

1. The effects exerted on secondary endings by repetitive stimulation of single static or single dynamic fusimotor fibres were studied in nine tenuissimus spindles in cats.2. The discharge of each secondary ending was recorded simultaneously with the discharge of the primary ending belonging to the same spindle.3. All the nineteen static fusimotor fibres studied activated secondary endings.4. Of eight dynamic fusimotor fibres, seven had no action on secondary endings. One dynamic fibre activated an atypical secondary ending which displayed some phasic sensitivity.5. No difference in conduction velocity was found between static and dynamic fibres.6. The implications of these observations for the mechanism of action of static and dynamic fusimotor fibres are discussed.


Asunto(s)
Husos Musculares/fisiología , Animales , Gatos , Estimulación Eléctrica , Electrofisiología , Conducción Nerviosa/fisiología , Fenobarbital
17.
Psychosom Med ; 59(5): 529-32, 1997.
Artículo en Inglés | MEDLINE | ID: mdl-9316186

RESUMEN

OBJECTIVE: It has been reported that sleep deprivation may enhance interleukin (IL)-1 beta production of healthy subjects. Furthermore, patients with acute psychoses have been reported to exhibit higher levels of IL-1 beta than healthy controls. The present study examined polysomnographic sleep and morning IL-1 beta plasma values in 20 drug-free patients with acute nonaffective psychoses. METHODS: Ten patients with DSM-III diagnosis of schizophrenia, five with delusional disorder, and five with atypical psychosis underwent polysomnographic sleep registrations and their morning blood levels of IL-1 beta were measured. RESULTS: IL-1 beta values correlated negatively with the length of the sleep period (p = 0.010) and the relative time of rapid eye movement (REM) sleep (p = 0.038), and positively with REM latency (p = 0.043). CONCLUSIONS: It is concluded that reduced sleep, possibly especially reduced REM sleep, may be a reason for increased morning IL-1 beta values in these patients. Additional studies on IL-1 beta in psychiatric patients should consider the possibility of sleep disturbances as a possible explanation for deviations in IL-1 beta levels.


Asunto(s)
Interleucina-1/sangre , Trastornos Psicóticos/fisiopatología , Esquizofrenia/fisiopatología , Sueño/fisiología , Adolescente , Adulto , Estudios Transversales , Humanos , Persona de Mediana Edad , Polisomnografía , Privación de Sueño/fisiología , Sueño REM/fisiología
18.
J Interferon Res ; 13(3): 233-4, 1993 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-8366290

RESUMEN

Induced production of interferon-alpha (IFN-alpha) and IFN-gamma was studied in 101 blood samples from 49 healthy subjects during 1 year. The results indicate a seasonal variation of the IFN-producing capacity, with a decrease in summertime, in Finland.


Asunto(s)
Interferón-alfa/biosíntesis , Interferón gamma/biosíntesis , Estaciones del Año , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valores de Referencia
19.
J Physiol ; 329: 211-29, 1982 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-6216334

RESUMEN

1. Experiments were performed in forty-one cats anaesthetized with chloralose.2. The aim of the study was to investigate whether activity in stretch-sensitive muscle receptors may cause reflex effects in fusimotor neurones.3. Activity in fusimotor neurones was studied indirectly by recording from primary and secondary muscle spindle afferents of the triceps surae muscle. The mean rate of firing of the afferents as well as either dynamic index (during ramp extension) or modulation (during sinusoidal extension) was determined. This was done under control conditions, with the posterior biceps-semitendinosus muscles relaxed, and under test conditions, with the same muscles extended.4. All together, seventy-one primary afferents were studied quantitatively. Pure or predominantly dynamic effects were observed in twenty-two, pure or predominantly static effects in nine and no statistically significant effects in forty of the units. Amongst seven secondary afferents studied, two showed weak fusimotor activation, the other five were not influenced.5. Electrical stimulation of the posterior biceps-semitendinosus or medial gastrocnemius nerves at group II strength was observed to cause dynamic fusimotor reflexes on a number of occasions.6. The reflex effects observed were, on many occasions, recorded in spinalized preparations.7. The reflex effects were not accompanied by any detectable e.m.g. activity in triceps, as judged from surface e.m.g. recordings. The reflex effects observed are therefore tentatively ascribed to activation of gamma-motoneurones, yet a contribution from beta-motoneurones cannot wholly be excluded.8. On the basis of available evidence concerning reflex connexions to gamma-motoneurones from various muscle afferents, it is suggested that the effects observed were caused by activation of muscle spindle secondary endings.


Asunto(s)
Mecanorreceptores/fisiología , Neuronas Motoras/fisiología , Husos Musculares/fisiología , Reflejo/fisiología , Animales , Gatos , Estimulación Eléctrica , Miembro Posterior , Conducción Nerviosa , Neuronas Aferentes/fisiología , Factores de Tiempo
20.
J Physiol ; 335: 237-53, 1983 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-6875876

RESUMEN

The reflex actions, elicited by graded electrical stimulation of hind-limb muscle, skin and joint nerves were studied in an extended series of experiments in extra-and intracellular recordings from 120 lumbar gamma-motoneurones of cats anaesthetized with chloralose. The present report deals with the action of group I muscle afferent fibres, which was examined in ninety-five gamma-cells. Of the gamma-cells 83% were classified as either static or dynamic by stimulation in the mesencephalic area for dynamic control. The general responsiveness (i.e. number of input nerves with effect/number of input nerves tested) of the cells was very high (89.9%). The responsiveness to stimulation of group I muscle afferent fibres was extremely low, both in flexor and extensor gamma-motoneurones and irrespective of whether they were static or dynamic. There was no difference, as regards the low incidence of group I muscle reflex action, between stimulation of autogenetic and heteronymous nerves. Among the rare reflex effects elicited from group I muscle fibres inhibition was four times as frequent as excitation. Inhibitory effects could be provoked from the autogenetic as well as from the heteronymous nerves. In contrast, excitatory effects were almost always autogenetic. The scarcity of group I muscle action on gamma-motoneurones is in striking contrast to the well known and powerful reflex actions of Ia and Ib fibres on alpha-motoneurones. These findings are discussed in relation to the concept of alpha-gamma linkage, and it is concluded that skeletomotor and fusimotor activity cannot be rigidly linked under all conditions.


Asunto(s)
Neuronas Motoras gamma/fisiología , Neuronas Motoras/fisiología , Músculos/inervación , Neuronas Aferentes/fisiología , Potenciales de Acción , Animales , Gatos , Estimulación Eléctrica , Miembro Posterior , Articulación de la Rodilla/inervación , Reflejo/fisiología , Piel/inervación , Factores de Tiempo
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