RESUMO
Antibody microprobes were used to study the release of immunoreactive neurokinin A into the spinal cord of anaesthetised cats during and following injection of a knee joint with kaolin and carrageenan. A basal level of immunoreactive neurokinin A was detected prior to any noxious stimuli. Innocuous mechanical joint stimuli (flexion or pressure) did not alter this basal level of release. However, on injection of kaolin and carrageenan into a knee joint, evidence of release into the ipsilateral spinal cord was immediately observed. Initially, immunoreactive neurokinin A was detected in 2 regions: one at the dorsal surface of the spinal cord and the other centred on the superficial dorsal horn. Within 1 h of joint injection, however, immunoreactive neurokinin A was detected throughout the dorsal horn and the adjacent white matter. The extensive spread and persistence of immunoreactive neurokinin A in the spinal cord may underlie some of the prolonged excitability changes evoked by brief noxious stimuli and peripheral inflammation reported by other laboratories.
Assuntos
Artrite/metabolismo , Neurocinina A/metabolismo , Medula Espinal/metabolismo , Doença Aguda , Animais , Artrite/induzido quimicamente , Autorradiografia , Carragenina , Gatos , Modelos Animais de Doenças , Caulim , Sondas Moleculares , Estresse MecânicoAssuntos
Sistema Nervoso Central/fisiologia , Eletrofisiologia , Endorfinas/fisiologia , Entorpecentes/farmacologia , Animais , Gânglios da Base/fisiologia , Células Cultivadas , Cerebelo/fisiologia , Córtex Cerebral/fisiologia , Eletroquímica , Eletrofisiologia/métodos , Hipocampo/fisiologia , Humanos , Hipotálamo/fisiologia , Morfina/farmacologia , Junção Neuromuscular/fisiologia , Neurônios/fisiologia , Núcleo Accumbens/fisiologia , Nervos Periféricos/fisiologia , Especificidade da Espécie , Transmissão Sináptica/efeitos dos fármacos , Tálamo/fisiologiaAssuntos
Aminoácidos/farmacologia , Encéfalo/efeitos dos fármacos , Inibição Neural/efeitos dos fármacos , Neurotransmissores/farmacologia , Medula Espinal/efeitos dos fármacos , Acetilcolina/farmacologia , Animais , Tronco Encefálico/efeitos dos fármacos , Cerebelo/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Dopamina/farmacologia , Encefalinas/farmacologia , Hipocampo/efeitos dos fármacos , Histamina/farmacologia , Norepinefrina/farmacologia , Serotonina/farmacologia , Tálamo/efeitos dos fármacos , Ácido gama-Aminobutírico/farmacologiaRESUMO
Administered electrophoretically morphine depressed the firing of medial thalamic neurones. This effect was not antagonized by naloxone which itself was a depressant. A long lasting increase in sensitivity to L-glutamate followed ejection of both morphine and naloxone. Intravenous morphine, 0.5-1.5 mg/kg, had inconstant effects on spontaneous firing that evoked by electrical stimulation of the forepaws but in 7 of 10 experiments reduced the sensitivity of neurones to L-glutamate. This effect was reversed in all cases by intravenous naloxone, 0.3 mg/kg
Assuntos
Morfina/farmacologia , Naloxona/farmacologia , Tálamo/efeitos dos fármacos , Acetilcolina/farmacologia , Potenciais de Ação/efeitos dos fármacos , Animais , Gatos , Depressão Química , Interações Medicamentosas , Potenciais Evocados/efeitos dos fármacos , Glutamatos/farmacologia , Morfina/administração & dosagem , Naloxona/administração & dosagem , Neurônios/efeitos dos fármacos , Tálamo/citologiaRESUMO
Morphine, naloxone, nalorphine, levorphanol, dextrorphan and levallorphan were ejected electrophoretically from micropipettes near cholinoceptive and noncholinoceptive cells of the spinal cord, ventrobasal thalamus and cerebral cortex of decerebrate and barbiturate-anesthetized cats. Morphine excited those cells having nicotinic receptors for acetylcholine. Naloxone and nalorphine reduced the action of morphine and acetylcholine on these cells but not the effects of excitant amino acids. Levorphanol excited spinal neurons also excited by acetylcholine, an effect antagonized by naloxone, but also showed atropine-like activity when ejected for prolonged periods. Dextrorphan depressed the firing of both cholinoceptive and noncholinoceptive spinal neurons. Levallorphan reduced the effects of both acetylcholine and excitant amino acids on spinal neurons. The depressant effects of morphine and levorphanol on noncholinoceptive spinal neurons were not antagonized by naloxone.