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Updated: Aug 19, 2026

Rapid In Situ Hybridization using Oligonucleotide Probes on Paraformaldehyde-prefixed Brain of Rats with Serotonin Syndrome
Published on: September 23, 2015
Diurnal variation in serotonin immunoreactivity in the dorsal raphe nucleus
Melissa Birkett1, Katherine V Fite
1Department of Neuroscience and Behavior Program, Tobin Hall, University of Massachusetts, Amherst, MA 01003-9271, USA.
Abstract:
Serotonin (5-HT) immunostained sections were analyzed using integrated optical density (IOD) measures obtained throughout the dorsal raphe nucleus (DRN) in Mongolian gerbils at selected times during a 12:12 h light:dark cycle. Substantial diurnal variation occurred in 5-HT neuronal staining density, with lowest and highest IOD values occurring at the light/dark and dark/light transitions, respectively. The injection of pargyline and tryptophan increased 5-HT immunostaining comparable to the highest level observed in control animals. Transitions between light and dark periods appear to be major environmental events that influence 5-HT levels in the DRN.