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Exploring the Role of Vasopressin in Modulating Corticosteroid Activity

Sacha James, 2nd year PhD, University of Exeter

BACKGROUND:

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I am a second-year PhD student studying neuroendocrinology: I specialise in the study of the Hypothalamic Pituitary Adrenal Axis (HPA) which is the system in the body that controls cortisol and is responsible for our stress response.

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My PhD is aiming to understand how elevated Vasopressin concentrations within the HPA change the activity of the axis and its ability to respond to stress. Vasopressin is a protein of the hypothalamus within the HPA which is increased by stress, and which naturally increases in concentration with age. We do not currently know how elevated Vasopressin changes specific activity patterns of the HPA stress axis and so this is the basis for my project.

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METHODOLOGY: 

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To study certain aspects of the HPA, I will be using a new transgenic animal model which will allow us to interact with the CRH-neurons of the hypothalamus which are involved in the stress axis. Using this model, we were able to specifically target the CRH neurons of the hypothalamus with a fluorescent virus. The results of this virus can be seen in the image below in green. The images below in red show the staining from an antibody used to stain the same CRH neurons. The overlap of the two stains in the third image confirms that the transgenic neurons of the model are specifically CRH neurons and not just generic populations in the hypothalamus.

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Recently I have been conducting similar experiments to fluorescently stain the brains of these transgenic animals. I have also been testing a new protocol where we administer a chemical Colchicine to block the movement of proteins in the brain, this is to increase protein concentrations and ensure that protein staining is stronger and brighter when imaged.

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FUTURE WORK: 

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I aim in the coming months to repeat this protocol in older animals to compare how their protein staining in the hypothalamus changes with age. These experiments will confirm two things: 1) that transgenic animals have functioning HPA axis with normal protein expression, and 2) that older transgenic animals have increased Vasopressin protein concentration. Once these points can be confirmed I will be able to conduct further experiments to assess how neuronal activity and rhythmicity are changed in high-vasopressin-concentration models.

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FUNDED BY:

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CONTACT:

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