June 22nd, 2009
Today I finished taking pictures through the microscope, which came to a grand total of 205 images. With this many pictures I will be able to gather tons of useful data. I havent really explained why we are interested in the AT1 receptors yet on this blog so I’ll do a brief overview now. The animals (rats and hampsters) have been split into four groups (not mixed between species). The groups consist of the hypertensive (high blood pressure) animals, the normotensive (regular blood pressure), the captopril-treated hypertensive group (high blood pressure given a drug to lower it), and the hypertensive group that was briefly given captopril then taken off of it. The reason why we are interested in this study is because when you give the hypertensive rats captopril to lower their blood pressure but then stop giving the drug to them you would expect that their blood pressure would go back to a hypertensive range (about 160 mmHg). Instead it stays about 20-30 mmHg lower than it was originally, even though the drug has not been administered for weeks. We are trying to find a change in the amount of these AT1 receptors (proteins) in the brain to see if we can explain the lowered blood pressure off the drug. The simplified version behind raising your blood pressure is when your body binds angiotensin II (a neurotransmitter) to its receptors, AT1, and this causes vasoconstriction (narrowing of the blood vessels) to increase the pressure. Its kind of alot of information to try to decypher at one time but thats a brief overview of the project I’m working on right now. Tomorrow I am going to start gathering the data which I do have some pictures to explain it visually.
Here’s a picture of the scale at 10x magnification. This enables me to measure the area of the brain regions by setting a scale from pixels to mm.
This is a picture of the Hypoglossal Nucleus at 10x. I am measuring the area inside the yellow dotted lines.
This is a picture of the ventral and dorsal regions that I am counting neurons in. This is of the hypoglossal nucleus at 40x. Some of the neurons are circled in yellow.
Mitch1980's Blog 
Interesting study. You state that you have a lot of information to handle, which you do, so I was wondering if an outline of the background information that will be in your paper will help? Not only will it be useful for people who don’t understand the material, but it would also be helpful for your paper.
B. F. Pons
Hi Bo, The way we handle the information is through excel documents. Excel is great for calculating StDev and using other tools like graphs.
Interesting project. To clarify, you are predicting that administering captopril lowers the number of AT1 receptors in the hypoglossal nucleus? And, this would explain the lower bp after stopping the treatment. Also, has this phenomenon been observed in humans that are hypertensive, take blood pressure medication, and then stop, or is does this drug work through a different pathway then current hypertension meds? Thanks–Adam
Adam, you are dead on with your analysis. The drug, captopril, does use the same pathology as other high blood pressure treatments. As far as I know about the human to rat pathways, it should be the same but I will have to check into it further. Also similar studies have yet to be done on humans by means of giving him/her the drug and then removing it so no answer there. That’s why we are interested in this project because it really hasn’t been researched yet, especially in the brain.
This project sounds very intresting. Do you guys have any hypothesis on why the blood pressure changes after or is it still a mystery? Is the drug you are using one that is currently in the market or is your group developing a new one?
Doorn, We hypothesize that there is some kind of down regulation of the AT1 receptors when the drug is given. This might be the reason why the bp stays lower after captopril is removed. Also, captopril is currently available, we didn’t develop it.
Interesting project. Is the drug that your group using one that is already out or is it one that your group is developing? Do you have any idea why the blood pressure never returns to pre drug usage level?
See the comment above…
Sorry, I wasn’t sure if it went through.
I think these pics are awesome! I’m also looking forward to reading your findings. I’m not too into Bio so the process to get to the findings is a little rough for me to wrap my head around. I think I’m going to have to have my husband translate all these U.Discover science studies into basic English so I can come up with more substantive comments beyond liking your photos. That’s almost as unsubstantive as telling you that I like your shoes.
Ok, I did think of one question. I’ve seen people be able to focus on slowing their breathing and relaxing to help reduce their blood pressure with decent results. Over time, they are able to slow breathing and stay more relaxed through the day without thinking about it thus having a permanent effect on their blood pressure. Do you think the residual lower blood pressure you are seeing could be something behavioral in the animal? For instance, they get used to feeling less tense while on the drug and just don’t go back to being tense afterwards? Sorry if that question sounds like it came from a 5th grader 🙂
Hey Mitch, I don’t have much for helpful/insightful comments (everyone else seems to be on top of that!), but I am going to throw out there that the pictures really help to clarify the process and what you’re looking for! Keep up the good work!
This is a very interesting study you are conducting. The major question I have is what you plan to do with your findings. Are you going to try and use these finding to help lower blood pressure in humans? If so it will be fascinating to see what happens. I cannot wait to see what you do find once you analyze all of your data! Keep up the good work!
You refer in your comment to Bo of standard deviations used in calculations conducted using Excel. I am interested in what your preliminary comparisons demonstrate. Moveover, do you assume that a normal curve exists in order to compute comparisons with your actual data? Or has a normal curve been established via scientific study which outlines the extent of presence of this receptor “normally” in various research subjects?