Arginine vasopressin increases glutamate release and intracellular Ca²⁺ concentration in hippocampal and cortical astrocytes through two distinct receptors

• Published in: Journal of neurochemistry 2007-10, Vol.103 (1), p.229-237
• Main Authors: Syed, Nasser, Martens, Catherine A, Hsu, Walter H
• Format: Article
• Language: English
• Subjects: Aggressiveness; Animals; Animals, Newborn; Anxiety; Arginine Vasopressin - pharmacology; Arginine Vasopressin - physiology; Astrocytes - drug effects; Astrocytes - metabolism; Biochemistry; Biological and medical sciences; Calcium - metabolism; Cells, Cultured; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; cerebral cortex; Cerebral Cortex - cytology; Cognition & reasoning; Enzyme Inhibitors - pharmacology; Excitatory Amino Acid Antagonists - pharmacology; Fundamental and applied biological sciences. Psychology; glutamate release; Glutamic Acid - metabolism; hippocampus; Hippocampus - cytology; Intracellular Fluid - metabolism; Isolated neuron and nerve. Neuroglia; Neurology; phospholipase A; phospholipase A2; Phospholipases A - antagonists & inhibitors; Rats; Rats, Sprague-Dawley; Receptors, Vasopressin - classification; Receptors, Vasopressin - metabolism; Rodents; V1a receptors; V1b receptors; Vertebrates: nervous system and sense organs; V₁a receptors; V₁b receptors
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/j.1471-4159.2007.04737.x

Arginine vasopressin (AVP), released from the CNS, plays an important role in regulating several aspects of CNS functions including aggression, anxiety, and cognition. In this study, we report a novel finding that AVP induces glutamate release from astrocytes isolated from the cerebral cortex and hippocampus. We also investigated the types of AVP receptors involved in the AVP-induced increase in glutamate release from astrocytes isolated from the hippocampus and cortex of neonatal rats. We showed that the AVP (0.1-1000 nmol/L) induced increase in glutamate release and [Ca²⁺]i is brought about by two distinct subtypes of V₁ receptors (V₁a and V₁b). Our results suggested that V₁b receptors are predominantly expressed in astrocytes isolated from the hippocampus and V₁a receptors are solely expressed in astrocytes isolated from the cerebral cortex of neonatal rats. The results of the western blot analyses confirmed these pharmacological data. In addition, the AVP-induced increase in glutamate did not contribute to an increase in [Ca²⁺]i, as blockade of metabotropic glutamate receptors did not alter the AVP-induced increase in [Ca²⁺]i. In addition, the administration of a phospholipase A₂ inhibitor failed to alter AVP-induced [Ca²⁺]i increase suggesting the lack of involvement of this enzyme.