User:Danielmcstay/sandbox

Hi this is my talk page - feel free to leave a message sometime Danielmcstay (talk) 09:11, 27 September 2017 (UTC)

This is my sandbox

The protein Annexin 1(ANXA1), found in high quantities in the anterior pituitary gland, is located specifically in the folliculostellate cell. In addition to the anterior pituitary gland, it can also be found in the non-endocrine cells of the hypothalamus. In both these anatomical sites – Annexin 1 acts to inhibit the release of ACTH and CRH, respectively. The protein is stimulated to do this by glucocorticoids and is consequently a mediator of glucocorticoid induced suppression of the Hypothalamic-Pituitary-Adrenal Axis (HPA axis).

Glucocorticoid induced suppression of the HPA axis has 2 components. Firstly, within 15 minutes of increased glucocorticoid exposure in the anterior pituitary, there is a reduction in the release of preformed ACTH. Secondly, glucocorticoids act at a genomic level by suppressing the translation of ACTH and CRH – this process takes 2 hours after exposure to increased glucocorticoid.

Glucocorticoids act on the folliculostellate cells to increase synthesis of ANXA1 and then stimulate its translocation to the cell surface of the FS cell. This translocation is dependent on protein kinase C. ANXA1 subsequently acts on the endocrine cells of the anterior pituitary, which express ANXA1 G protein coupled receptors, via a paracrine mechanism. The downstream signalling pathway which culminates in reduced ACTH synthesis and/or release remains largely unexplored and as consequence remains poorly understood.

The glucocorticoid/folliculostellate cell relationship also has a role in the production of the excitatory neurotransmitter glutamine. Cells in rat anterior pituitary gland which contain large quantities of the enzyme glutamine synthetase also express the S100 protein which is the marker for folliculostellate cells. After exogenous glucocorticoid administration, the number of these cells increases and the activity of glutamine synthetase also increases. This enzyme is necessary as it allows the CNS to produce glutamine internally. This is essential as the quantity of glutamine transported from the peripheral blood to the CNS cannot satisfy the demands of the CNS for glutamine.