Second messenger cascade of glial responses evoked by interneuron activity and by a myomodulin peptide in the leech central nervous system.
Eur J Neurosci
; 19(4): 983-92, 2004 Feb.
Article
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| MEDLINE
| ID: mdl-15009146
ABSTRACT
The giant glial cell in the neuropil of segmental ganglia of the leech Hirudo medicinalis responds to the activity of the Leydig interneuron and to a peptide of the myomodulin family, the presumed transmitter mediating the Leydig neuron-to-giant glial cell transmission, with a membrane hyperpolarization due to an increased membrane K+ conductance [Britz et al. (2002) Glia, 38, 215-227]. We have now studied the second messenger cascade initiated by Leydig neuron stimulation and by the endogenous myomodulin (MMHir) in the voltage-clamped giant glial cell. Glial responses to both stimuli are mediated by a G-protein-coupled receptor linked to adenylyl cyclase by the following criteria (i) injection of GDP-beta-S, but not GDP, resulted in an irreversible decrease of the glial responses to both stimuli; (ii) the responses to both stimuli were reversibly inhibited by the adenylyl cyclase inhibitor SQ22,536; and (3) bath-applied di-butyryl-cyclic AMP, but not di-butyryl-cyclic GMP, elicited an outward current, which reduced the responses elicited by neuronal stimulation or myomodulin. A cocktail of protein kinase (PK) inhibitors (H-8, KT5720), the PKA antagonist Rp-cAMPS, or presumed inhibitors of cyclic nucleotide channels, LY83583 and l-cis-diltiazem, had no effect on the glial responses. Our results suggest that Leydig neuron stimulation and MMHir activate a cAMP-mediated K+ conductance in the glial cell, which appeared neither to be due to the activation of PKA nor of known cyclic nucleotide-gated channels directly.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Neuropéptidos
/
Sistemas de Mensajero Secundario
/
Neuroglía
/
Interneuronas
/
Sanguijuelas
Límite:
Animals
Idioma:
En
Revista:
Eur J Neurosci
Asunto de la revista:
NEUROLOGIA
Año:
2004
Tipo del documento:
Article
País de afiliación:
Alemania