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An intrinsic CRF signaling system within the optic tectum
James A Carr1, Bo Zhang, Wenjie Li
1Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409, USA. james.carr@ttu.edu
General and Comparative Endocrinology
|April 16, 2013
Summary
Corticotropin-releasing factor (CRF) acts in the optic tectum of Xenopus laevis frogs. This brain region is key for visually guided feeding, suggesting CRF modulates sensory-motor pathways for food intake.
Area of Science:
- Neuroscience
- Animal Behavior
- Molecular Biology
Background:
- Previous studies show corticotropin-releasing factor (CRF) inhibits visually guided feeding in amphibians.
- The optic tectum integrates visual and premotor pathways crucial for feeding behaviors in anurans.
Purpose of the Study:
- To investigate if CRF functions as a neurotransmitter within the optic tectum.
- To explore the role of CRF signaling in regulating visually guided feeding in Xenopus laevis.
Main Methods:
- Reverse transcriptase PCR to detect CRF and CRF receptor mRNA expression in the optic tectum.
- Radioligand binding assays using CRF R1 antagonists to assess receptor interactions.
- Measurement of neurotransmitter secretion (norepinephrine, glutamate, GABA) from tectal explants.
- Radioimmunoassay to quantify CRF release from brain tissue.
Main Results:
- Optic tectum cells express mRNA for CRF and the CRF R1 receptor.
- CRF R1 antagonists blocked CRF's effect on regulator of G-protein signaling 2 (rgs2) mRNA expression.
- CRF inhibited norepinephrine secretion from tectal explants, an effect blocked by CRF R1 antagonists.
- CRF release from tectal explants is potassium- and calcium-dependent and higher than in other brain regions.
Conclusions:
- The optic tectum possesses a functional CRF signaling system.
- This system likely modulates communication within sensory-motor pathways involved in food intake regulation.
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