Glutamate and GABA presence and action in the suprachiasmatic nucleus.

Glutamate and gamma-aminobutyrate (GABA) are two neurotransmitters that appear to play an important role in the hypothalamic suprachiasmatic nucleus (SCN) and in the adjacent areas of the medial hypothalamus. Converging evidence based on ultrastructural immunocytochemistry, molecular biology, calcium imaging, and electrophysiology suggests not only that GABA and glutamate are used for inhibitory and excitatory activity, respectively, in this region of the rat brain, but that these two fast-acting amino acids may account for the majority of neurotransmission there.