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Updated: Aug 30, 2026
Assay for Neural Induction in the Chick Embryo
Published on: February 13, 2009
Changes in the content of progesterone receptor isoforms and estrogen receptor alpha in the chick brain during
Ignacio Camacho-Arroyo1, Aliesha González-Arenas, Gabriela González-Agüero
1Departamento de Biología, Facultad de Qui;mica, Universidad Nacional Autónoma de México, Ciudad Universitaria, Coyoacán 04510, México, DF, Mexico. igcamacho55@hotmail.com
Insights
Progesterone receptors (PR) and estrogen receptors alpha (ER-alpha) show developmental changes in chick brains. These hormone receptors exhibit sexual dimorphism, indicating distinct roles in male and female brain development.
Area of Science:
- Neuroendocrinology
- Developmental Biology
- Molecular Endocrinology
Background:
- Progesterone receptors (PR) and estrogen receptors alpha (ER-alpha) are key regulators of reproductive functions.
- These receptors interact with progesterone and estradiol, respectively, influencing cellular processes.
- Understanding their expression patterns is crucial for comprehending reproductive development and function.
Purpose of the Study:
- To quantify PR and ER-alpha isoform content in the developing chick brain.
- To investigate potential sex differences in receptor expression during embryonic development.
- To correlate receptor levels with brain maturation stages.
Main Methods:
- Western blot analysis was employed to determine protein content.
- Samples were collected from chick brains at embryonic days 8 and 13, and on the day of hatching.
- Analysis was performed on both male and female chicks.
Main Results:
- PR isoforms protein content increased throughout embryonic development in both sexes, peaking at hatching.
- PR-A content and the PR-A/PR-B ratio were higher in male chick brains than in females at all measured ages.
- Two ER-alpha isoforms (66 and 52 kDa) were detected; their expression patterns differed between sexes and developmental stages, with higher levels in females early on and increasing levels in males as development progressed.
Conclusions:
- PR and ER-alpha isoform content in the chick brain is associated with the developmental stage.
- Significant sexual dimorphism in PR and ER-alpha isoform expression exists in the developing chick brain.
- These findings suggest distinct roles for progesterone and estrogen signaling in sex-specific brain development.
Abstract:
Progesterone and estradiol participate in the regulation of several reproductive functions through interaction with intracellular progesterone receptors (PR) and estrogen receptors (ER), respectively. In this work, we determined PR and ER-alpha isoforms content in the brain of chicks of both sexes on days 8 and 13 of embryonic development as well as on the day of hatching by Western blot analysis. PR isoforms protein content increased during embryonic development in both female and male chick brain. The highest PR isoforms content was observed on the day of hatching in both sexes. Interestingly, PR-A content was higher in the brain of chick males than in that of females on day 8 of embryonic development. PR-A/PR-B ratio was higher in the brain of males than in that of females at all ages. We found two ER-alpha isoforms of 66 and 52 kDa; the content of both isoforms was higher in the brain of females than in that of males on days 8 and 13 of embryonic development. An opposite pattern of ER-alpha isoforms content was observed. In males, ER-alpha content increased during embryonic development whereas in the females it decreased during this process. These results indicate that the content of PR and ER-alpha isoforms is related to the degree of brain development in chicks, and suggest that PR and ER-alpha isoforms should exhibit sexual dimorphism in the brain of chicks during embryonic development.
