RESUMEN
The existence of a large number of receptors coupled to heterotrimeric guanine nucleotide binding proteins (G proteins) raises the question of how a particular receptor selectively regulates specific targets. We provide insight into this question by identifying a prototypical macromolecular signaling complex. The beta(2) adrenergic receptor was found to be directly associated with one of its ultimate effectors, the class C L-type calcium channel Ca(v)1.2. This complex also contained a G protein, an adenylyl cyclase, cyclic adenosine monophosphate-dependent protein kinase, and the counterbalancing phosphatase PP2A. Our electrophysiological recordings from hippocampal neurons demonstrate highly localized signal transduction from the receptor to the channel. The assembly of this signaling complex provides a mechanism that ensures specific and rapid signaling by a G protein-coupled receptor.
Asunto(s)
Canales de Calcio Tipo L/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Transducción de Señal , Adenilil Ciclasas/metabolismo , Agonistas de Receptores Adrenérgicos beta 2 , Albuterol/farmacología , Animales , Canales de Calcio Tipo L/genética , Línea Celular , Membrana Celular/metabolismo , Proteínas Quinasas Dependientes de AMP Cíclico/metabolismo , Conductividad Eléctrica , Técnica del Anticuerpo Fluorescente , Proteínas de Unión al GTP Heterotriméricas/metabolismo , Humanos , Isoproterenol/farmacología , Cinética , Sustancias Macromoleculares , Neuronas/citología , Neuronas/efectos de los fármacos , Neuronas/enzimología , Neuronas/metabolismo , Fosfoproteínas Fosfatasas/metabolismo , Pruebas de Precipitina , Prosencéfalo/citología , Prosencéfalo/metabolismo , Unión Proteica , Células Piramidales/citología , Células Piramidales/efectos de los fármacos , Células Piramidales/enzimología , Células Piramidales/metabolismo , Ratas , Receptores Adrenérgicos beta 2/genética , Especificidad por SustratoRESUMEN
Using immunohistochemical detection of the Fos protein as a cellular marker of neuronal activation, we examined forebrain areas that may be activated upon chemical stimulation of the laryngeal opening. Anesthetized rats were subject to multiple infusions of a chemical solution into the laryngopharynx. These animals were compared to two control groups: a surgical control group in which the animals were subject to the surgical procedure but received no stimulus infusions and a flow control group in which physiological saline replaced the chemical stimulus. Comparing the numbers of Fos-like-immunoreactive neurons in regions of the forebrain across groups revealed that infusing the chemical stimulus solution into the laryngopharyngeal opening selectively increased the number of Fos-like-immunoreactive nuclei in the paraventricular nucleus of the hypothalamus and the central nucleus of the amygdala, two autonomic-visceral related forebrain regions. Within the paraventricular nucleus of the hypothalamus, Fos-like-immunoreactive nuclei were significantly increased in the parvocellular subdivision while in the central nucleus of the amygdala, significant increases in Fos-like-immunoreactive nuclei were limited to the lateral capsular subdivision. These data suggest that in the rat laryngopharyngeal chemosensory stimulation activates forebrain regions that receive oral sensory information and are involved in visceral and autonomic functions.
