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Updated: Aug 24, 2026

Simultaneous Electrophysiological Recording and Calcium Imaging of Suprachiasmatic Nucleus Neurons
Published on: December 8, 2013
Serotonin innervation of the primate suprachiasmatic nucleus
1Departments of Neurology and Neuroscience, University of Pittsburgh, 3471 Fifth Avenue, Suite 811, Pittsburgh, PA 15213, USA. rym@pitt.edu
Abstract:
The suprachiasmatic nucleus (SCN) in rodents receives a dense innervation from serotonin neurons of the midbrain raphe. This projection overlaps the terminal field of the retinohypothalamic tract in the SCN core, the central part of the nucleus characterized by a population of vasoactive intestinal polypeptide (VIP)-containing neurons. To determine whether a similar pathway is present in primates, we carried out an immnunocytochemical investigation of the primate SCN using antisera against either serotonin (monkey) or the serotonin transporter (human). This demonstrated a dense serotonergic plexus over the SCN core in both species. As in rodents, the distribution of the serotonin innervation of the primate SCN overlaps that of the retinohypothalamic input and the VIP neuronal population. We also find a supraependymal plexus of serotonin axons in the third and lateral ventricles of the human and monkey brains that is similar in distribution, but less dense, than the one reported in rodents.
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