Glutamatergic neurotransmission as molecular target in anxiety

Glutamate (GLU) is the main excitatory neurotransmitter in the mammalian brain. GLU receptors are classified as ionotropic (iGLUR) or metabotropic (mGLUR). The GLU interference with neural development, synaptic plasticity, learning and memory, epilepsy, neural ischemia, drug addiction, tolerance, neuropathic pain, anxiety and depression, has limited the use of compounds acting on GLU synapses, when there is a need for a selective effect for these drugs. Pre-clinical data in rodents and humans subjects has shown that compounds that reduce GLU activation either by blocking its receptors or by reducing its release from terminals elicit an anxiolytic profile of action in models of anxiety. When applied to specific brain areas involved in the mediation of defensive behavior, such as the periaqueductal gray matter, these compounds also replicate the same anxiolytic-like profile. The increasing knowledge about GLU neurotransmission and the development of more selective GLU-acting compounds have renewed attention towards this neurotransmismiting system as a possible target for new classes of drugs for the treatment of neuropsychiatric conditions. Although not complete this review tried to draw attention to collaborative studies between clinicians and basic researchers that have provided insight for potential targets in the development of new anxiolytic compounds thus contributing for the understanding of the biological basis of anxiety.