Excitatory amino acid receptors coupled to the phosphoinositide pathway in Bergmann glia

• Published in: Neurochemical research Vol. 22; no. 3; pp. 305 - 312
• Main Authors: LOPEZ-COLOME, A. M, ORTEGA, A, FRAGOSO, G, TRUEBA, E
• Format: Journal Article
• Language: English
• Published: New York, NY Springer 01.03.1997; Springer Nature B.V
• Subjects: AMP; Animals; Astrocytes - drug effects; Astrocytes - metabolism; Biological and medical sciences; Calcium Channels - drug effects; Cells, Cultured; Cerebellum - drug effects; Cerebellum - embryology; Cerebellum - metabolism; Chick Embryo; Cycloleucine - analogs & derivatives; Cycloleucine - pharmacology; Fundamental and applied biological sciences. Psychology; Glutamic Acid - pharmacology; Hydrolysis; Isolated neuron and nerve. Neuroglia; Neuroglia - drug effects; Neuroglia - metabolism; Phosphatidylinositols - metabolism; Quisqualic Acid - pharmacology; Receptors, Glutamate - drug effects; Receptors, Glutamate - metabolism; Receptors, Metabotropic Glutamate - agonists; Stimulation, Chemical; Vertebrates: nervous system and sense organs; Cerebellum; Vertebrata; Glial cell; Phosphoinositide; Neuroglia; Central nervous system; Chicken; Glutamate receptor; Inositol phosphate; Aves; Brain (vertebrata)
• ISSN: 0364-3190; 1573-6903
• DOI: 10.1023/A:1022494923084

Glutamate (L-glu) receptors coupled to phosphoinositide hydrolysis in primary cultures of Bergmann cells from chick cerebellum were characterized biochemically and pharmacologically. Both ionotropic and metabotropic receptor agonists stimulated [3H] inositol phosphates accumulation in the following order of potency: QA > NMDA > L-glu > KA approximately QA > AMPA > > t-ACPD. QA showed a biphasic dose-response curve (EC50 = 0.07 and 53 microM), suggesting interaction with two populations of receptors; L-glu was the most efficient agonist. Stimulation by NMDA was blocked by CPP, AP5 and MK-801; that by AMPA and KA was inhibited 100% by CNQX and DNQX, whereas the effect of QA was decreased both by CNQX and the metabotropic antagonist 4-CPG. Stimulation of PIP2 hydrolysis induced by metabotropic L-glu receptor agonist t-ACPD was blocked by 4-CPG but was only moderately inhibited by MCPG. EAA-induced [3H]IPs accumulation was dependent on external Ca2+ and was not affected by nifedipine verapamil, or dantrolene; thapsigargin increased the effect. Results suggest that EAA activate the PI pathway in Bergmann glia through ionotropic (NMDA and AMPA/KA) as well as metabotropic receptor subtypes (t-ACPD) which could act jointly influencing neurotransmission at the parallel fiber-Purkinje cell synapses in the cerebellum.