Developmental changes in serotonin levels in the chick spinal cord and brain
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Updated: Aug 14, 2026
Spinal Cord Electrophysiology
Published on: January 19, 2010
N Okado1, S Shibanoki, K Ishikawa
1Department of Anatomy, University of Tsukuba, Ibaraki, Japan.
Insights
This study tracked serotonin (5-HT) and its metabolite (5-HIAA) in developing chicks. Spinal cord levels initially rose, peaking post-hatching, then declined, while brain levels steadily increased.
Area of Science:
- Neuroscience
- Developmental Biology
- Biochemistry
Background:
- Serotonin (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) are crucial neurotransmitters.
- Understanding their developmental trajectory is key to comprehending nervous system maturation.
Purpose of the Study:
- To investigate the developmental changes of 5-HT and 5-HIAA in the chick spinal cord and brain.
- To map the regional and temporal distribution of these compounds during embryonic and post-hatching periods.
Main Methods:
- High-performance liquid chromatography with electrochemical detection (HPLC-ECD).
- Immunohistochemistry.
- Analysis of spinal cord and brain tissue from embryonic day 6 (E6) to post-hatching day 120 (P120).
Main Results:
- Initially, 5-HT and 5-HIAA were low in the spinal cord but high in surrounding non-neuronal tissue.
- Spinal cord 5-HT concentrations showed regional variations (cervical, thoracic, lumbar) that shifted with development.
- Spinal cord 5-HT peaked around post-hatching day 7 before declining, while brain 5-HT levels consistently increased throughout development.
Conclusions:
- The distribution and concentration of 5-HT and 5-HIAA undergo significant developmental changes in the chick nervous system.
- These changes suggest distinct roles and regulatory mechanisms for serotonin in the developing spinal cord versus the brain.
Abstract:
Developmental changes in 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in the developing chick spinal cord and brain were examined using high-performance liquid chromatography with electrochemical detection and immunohistochemistry. On embryonic day (E)6 only small amounts of 5-HT (0.086 ng) and 5-HIAA (0.0144 ng) were found in the spinal cord. By contrast, large amounts of 5-HT (x30) and 5-HIAA (x60) were detected in non-neuronal tissue outside the spinal cord; a similar distribution of 5-HT was also detected by immunohistochemistry. Up to E10, the highest concentrations of 5-HT in the spinal cord were found in the cervical region, followed by the thoracic and lumbar regions. In embryos older than E16, as well as in posthatched chicks, however, the highest and lowest concentrations of 5-HT were found in the lumbar and thoracic spinal cord, respectively. The concentration of spinal cord 5-HT reached maximal values on posthatching day (P)7, after which there was a marked decrease. By P120, 5-HT levels in the spinal cord decreased to the same level as on E10-E16. Concentrations in the brain, however, gradually increased with development. The basic pattern of development of 5-HIAA was similar to that of 5-HT.
