La activación de receptores AMPA/kainato, pero no la de receptores de acetilcolina, provoca un influjo de Mg²⁺ en las neuronas de Retzius de la sanguijuela Hirudo medicinalis

In Retzius neurones of the medicinal leech, Hirudo medicinalis, kainate activates ionotropic glutamate receptors classified as AMPA/kainate receptors. Activation of the AMPA/kainate receptor-coupled cation channels evokes a marked depolarization, intracellular acidification, and increases in the intracellular concentrations of Na+ ([Na+]i) and Ca2+. Qualitatively similar changes are observed upon the application of carbachol, an activator of acetylcholine receptor-coupled cation channels. Using multibarrelled ion-selective microelectrodes it was demonstrated that kainate, but not carbachol, caused additional increases in the intracellular free Mg2+ concentration ([Mg2+]i). Experiments were designed to investigate whether this kainate-induced [Mg2+]i increase was due to a direct Mg2+ influx through the AMPA/kainate receptor-coupled cation channels or a secondary effect due to the depolarization or the ionic changes. It was found that: (a) Similar [Mg2+]i increases were evoked by the application of glutamate or aspartate. (b) All kainate-induced effects were inhibited by the glutamatergic antagonist DNQX. (c) The magnitude of the [Mg2+]i increases depended on the extracellular Mg2+ concentration. (d) A reduction of the extracellular Ca2+ concentration increased kainate-induced [Mg2+]i increases, excluding possible Ca2+ interference at the Mg2+-selective microelectrode or at intracellular buffer sites. (e) Neither depolarizations evoked by the application of 30 mM K+, nor [Na+]i increases induced by the inhibition of the Na+/K+ ATPase caused comparable [Mg2+]i increases. (f) Inhibitors of voltage-dependent Ca2+ channels did not affect the kainate-induced [Mg2+]i increases. Moreover, previous experiments had already shown that intracellular acidification evoked by the application of 20 mM propionate did not cause changes in [Mg2+]i. The results indicate that kainate-induced [Mg2+]i increases in leech Retzius neurones are due to an influx of extracellular Mg2+ through the AMPA/kainate receptor-coupled cation channel. Mg2+ may thus act as an intracellular signal to distinguish between glutamatergic and cholinergic activation of leech Retzius neurones.

Resumen tomado de PubMed (NCBI) para el registro citado, en el idioma original. La versión de referencia es la de la publicación original.

El resumen se deja sin traducir para conservar la redacción original de los autores.

En neuronas de Retzius de Hirudo medicinalis, el kainato activa receptores AMPA/kainato y produce despolarización, acidificación intracelular y aumentos de [Na⁺]ᵢ y [Ca²⁺]ᵢ. A diferencia del carbacol, elevó el Mg²⁺ intracelular libre ([Mg²⁺]ᵢ). El antagonista DNQX bloqueó los efectos del kainato; reducir el Ca²⁺ extracelular potenció el aumento de [Mg²⁺]ᵢ, y los bloqueadores de canales de Ca²⁺ dependientes de voltaje no tuvieron efecto. Según los autores, el Mg²⁺ podría servir de señal para distinguir la activación glutamatérgica de la colinérgica.

Explore cómo esta investigación se conecta con la práctica clínica

Más estudios revisados por pares en la categoría «Genómica y proteómica».

• Leech Salivary Proteome and Transcriptome: 434 Deduced Protein Sequences — Liu Z, Tong X, Su Y, et al. (2019)
• Medicinal Leech Draft Genome — Anticoagulant Gene Survey — Kvist S, Manzano-Marín A, de Carle D, Trontelj P, Siddall ME (2020)
• La terapia con sanguijuelas (Hirudo medicinalis) atenúa las lesiones testiculares inducidas por isquemia/reperfusión testicular en un modelo animal — Davoodi F et al. (2021)
• Nueva proteína anticoagulante de la sanguijuela medicinal — Manuvera V et al. (2024)
• AIF-1 y RNASET2 desempeñan papeles complementarios en la respuesta inmunitaria innata de la sanguijuela medicinal — Baranzini N et al. (2019)
• Los péptidos antimicrobianos de la sanguijuela medicinal carentes de toxicidad representan una estrategia alternativa prometedora para combatir patógenos resistentes a antibióticos — Grafskaia E et al. (2019)
• Perspectivas estructurales sobre la actividad trombolítica de la destabilasa de la sanguijuela medicinal — Marin E et al. (2023)
• El genoma de la sanguijuela medicinal (Whitmania pigra) y un estudio genómico comparativo para la exploración de ingredientes bioactivos — Tong L et al. (2022)
• El SNC de la sanguijuela medicinal como modelo para estudios de exosomas en la comunicación cruzada entre microglía y neuronas — Raffo-Romero A et al. (2018)
• Transcriptomic profiling and the first spatial expression analysis of candidate genes in the salivary gland of the East Asian medicinal leech, Hirudo nipponia — Kim J et al. (2024)

Ver toda la investigación analizada por la ASH →