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Anterior pituitary thyrotropes are multifunctional cells
Carlos Villalobos1, Lucía Núñez, Javier García-Sancho
1Dept. Fisiología y Bioquímica, Facultad de Medicina, Instituto de Biología y Genética Molecular, University of Valladolid, E-47005 Valladolid, Spain.
Summary
Most thyrotropes are polyhormonal, co-storing other anterior pituitary (AP) hormones like luteinizing hormone and prolactin. Gender influences hormone combinations, suggesting thyrotropes are diverse cell phenotypes, not a single type.
Area of Science:
- Endocrinology
- Cell Biology
- Pituitary Physiology
Background:
- Anterior pituitary (AP) cells can be multifunctional, storing/secreting multiple hormones (polyhormonal) or responding to various hypothalamic-releasing hormones (HRHs; multiresponsive).
- These multifunctional cells may play roles in paradoxical secretion and transdifferentiation, processes crucial for AP regulation.
Purpose of the Study:
- To investigate the single-cell phenotype of thyrotropes in male and female mice.
- To determine the extent of polyhormonality and multiresponsiveness in thyrotropes.
Main Methods:
- Combined calcium imaging to assess responses to four HRHs.
- Performed multiple sequential immunoassays to detect six AP hormones at the single-cell level.
Main Results:
- Most thyrotropes were polyhormonal, co-storing thyrotropin (TSH) with luteinizing hormone (40-42%) and prolactin (19-21%).
- Thyrotropes co-storing growth hormone or ACTH were observed only in females (24% each).
- Polyhormonal thyrotropes showed weaker responses to thyrotropin-releasing hormone compared to monohormonal ones.
Conclusions:
- Thyrotropes exhibit a mosaic of phenotypes, co-storing various hormones, with gender-specific combinations.
- The observed hormone co-storage is not random and suggests finely regulated expression during potential transdifferentiation.
- Limited paradoxical secretion is predicted due to weaker responses in polyhormonal cells, indicating regulated HRH receptor expression.