Gliotransmission in physiologic and pathologic conditions.

This chapter explores the roles of gliotransmission in physiologic and pathologic conditions, including psychiatric and neurologic disorders. Gliotransmission, facilitated by astrocytes through the release of gliotransmitters such as glutamate, d-serine, and GABA, regulates neuronal activity and synaptic transmission. Under physiologic conditions, astrocytic gliotransmission maintains the balance of tonic excitation and inhibition, influencing synaptic plasticity and cognitive functions. In psychiatric disorders, the chapter examines how dysregulated gliotransmission contributes to major depression and schizophrenia. In major depression, changes in astrocytic glutamate and adenosine signaling impact mood regulation and cognitive functions. Schizophrenia involves complex astrocyte-neuron interactions, with dysregulated astrocytic activity affecting synaptic function and contributing to symptoms. The chapter also delves into neurologic disorders. In Alzheimer disease, aberrant GABA release from reactive astrocytes impairs memory and cognitive functions. Parkinson disease features alterations in glutamatergic and GABAergic systems, affecting motor and nonmotor symptoms. Epilepsy involves a disruption in the balance between excitatory and inhibitory neurotransmission, with astrocytic GABA accumulation helping to maintain neuronal stability. Autism spectrum disorder (ASD) is linked to imbalances in glutamatergic and GABAergic neurotransmission, underlying sensory, cognitive, and social impairments. Overall, the chapter underscores the pivotal role of gliotransmission in maintaining neural homeostasis and highlights its potential as a therapeutic target in various disorders.