This review considers many lines of evidence from diverse experimental approaches indicating that the RHT employs glutamate (or a related excitatory amino acid) as a neurotransmitter... glutamate is the principal neurotransmitter within the RHT, and thus conveys photic cues to the circadian timing system in the SCN.
First-pass extracted concept
retinohypothalamic tract glutamatergic photic signaling to the suprachiasmatic nucleus
Candidate: concept label1 source documents5 linked claims
Live refresh every 5sNext refresh in 5s
Evidence Snippets
Supporting Sources
Linked Claims
The review states that application of glutamate to in vitro preparations phase shifts persistent circadian electrical rhythms in a way that mimics light-induced phase shifting in vivo.
The review concludes that glutamate is the principal neurotransmitter used by the retinohypothalamic tract to convey photic cues to the suprachiasmatic nucleus.
The review summarizes evidence that glutamate is present in presynaptic terminals within the SCN and that multiple ionotropic and metabotropic glutamate receptor subunits are present in the SCN.
The review states that glutamate antagonists can block light-induced phase shifting of circadian rhythms and block light-induced c-fos induction in SCN cells, while NMDA induces c-fos expression.
The review states that electrical stimulation of the optic nerves in hypothalamic slices induces glutamate and aspartate release and evokes SCN field potentials that are blocked by glutamate antagonists.