Hi, I'm planning to induce sporadic Alzheimer's disease (AD) in male Sprague Dawley rats (3 months old, 270-350g) through bilateral intracerebroventricular microinjection of 3 mg/kg streptozotocin in the following coordinates; 0.9 mm posterior to bregma, 1.5 mm lateral to the sagittal suture, 3.6 mm beneath the surface of the brain. I need to know whether I need to do brain imaging for every single rats to validate the site of injection is within the desired site. Since the weight varies individually, i afraid the brain size might vary as well. Therefore, the drug may not be injected consistently to the same site in all rats. However, if we validate each rats, my concern is that we might not have enough brain samples to conduct the biochemical assessments as we will loss some brain tissues to the validation process.
Thank you.
Hi,
the brain atlas is a very useful resource. While it may sometimes be challenging on small structures, icv injections are pretty safe. You should look through the literature, and you can validate on a few rats first using dye or imaging if you prefer. The brain size may vary but stereotactic coordinates are given compared to bregma and lambda, they are not absolute values, so one round of test and you should be fine.
Dear Marie Mortreux thank you for your reply. It is indeed very helpful.
Hi Nurul Husna Ibrahim ,
I agree with Marie Mortreux .
Use: Paxinos, G., & Watson, C. (2006). The rat brain in stereotaxic coordinates for histological verification as you have used it for stereotaxic surgery. Postmortem imaging cannot be useful for this purpose as it is not a valid form of verification for verification of cannulae or electrode placement in rats and can be time consuming and expensive. Just do a random selection or a group of 8 rats for postmortem histological verification, as the brain size varies with age mostly rather than the weight (Zuker rats' brain size is almost equal to normal rats with half a weight but same age)
Using simple, accessible dyes like Crysl violet or even simple diluted ink in PBS or normal salin (for microinjection) can be great to track the cannulae placement trace. Then section the brains at the cannulae placements and check them under a loupe or microscope. You can take images for verification, report and publication.
If you would like, you can take a look at the procedure and obtained images in our papers:
Article Effects of dorsal hippocampal orexin-2 receptor antagonism o...
Article Chronic ghrelin administration restores hippocampal long‐ter...
- Badges
- Science topic