Hi, my name is Nicholas Basil. And I'm Zachary Mendola. And today we're going to be presenting our poster that is on our project currently, which is looking at the effects of repeated intranasal gentamicin exposure on the morphology of neurons within the vestibular nuclei. So we're looking at gentamicin, which falls under the aminoglycoside antibiotic class and is used primarily on gram-negative bacteria. So gentamicin has been around for quite some time now. There has been extensive research done on the drug. It's been looked at on its side effects, on what it can be used for, what it can't be used for. But one area that is lacking on it is looking at animal models with the intranasal route of administration specifically. So that is why we chose to use that route of administration. And one of its known side effects is ototoxicity. So we combined both of those to be able to get a better look at the effect of ototoxicity with the intranasal gentamicin exposure on the vestibular system. So your vestibular system is located within your inner ear, and it's very closely related to your hearing system. But the vestibular system is there to help you catch yourself if you fall. It's there to help yourself stand up straight. The whole purpose of the vestibular system is to recognize how your body is moving in space and if there's any significant changes that you need to do to protect yourself from getting hurt. So it's comprised of three semicircular canals that all have fluid flowing through them. And when that fluid changes in accordance to acceleration or deceleration, it's going to trigger sensors. And those sensors depolarize, and they signal onto cranial nerve 8, which is your vestibulocochlear nerve. And from there, it's going to send action potentials up into the brainstem to your vestibular nuclei. And you have four of them. You have your spinal, you have your superior, your lateral, and your medial. And from there, that information gets integrated. And then it's going to project to higher centers and help coordinate a response to help protect yourself. It goes to the thalamus, it's going to ocular nuclei, to the cerebellum, and even back down through the spinal cord so that, for instance, if I begin to fall, I know, whoa, I need to put my hands out so that I can catch myself. It's there for protection, right? And so we chose to continue with this model here because we've had previous data in our laboratory from other researchers who have shown that upon the administration of intranasal injection of gentamicin in rat models, there's significant behavioral changes that occur with these rats. Specifically, they were tested with vestibular challenges, varying models. And what the researchers had found was that the rats, when exposed, do have significant changes in their ability to respond to these vestibular challenges. So our goal here is to look at the morphological aspect of how the vestibular nuclei change. So after these rats were put through these vestibular challenges, we took them, we perfused them. After they were perfused, we took out their brains. After we took out their brains, we sliced their brain stem, which is where you will find the vestibular nuclei. We took every third slice, and we would mount them on a slide. We stained them, and then we put them under the microscope. So in the middle of the poster, you can see a more broader view of the nuclei. They're outlined in black there. You can see on the top, the superior and lateral, and on the bottom, you can see the medial and the spinal. Then on the right side of the poster, you can see, with the 40X magnification, you can see each nuclei with the neurons within them, what some of those may look like. And so what we did is we went under 40X magnification, and we traced a lot of these neurons, both in control and exposed, and we wanted to look at the size, the shape, the morphological side of these neurons, and compare them with just normal rats and the normal vestibular nuclei. And what we were able to find is we were able to find significant differences within each of the four vestibular nuclei. Within all four, we were able to find significant changes with the cellate neurons, and in the spinal vestibular nuclei, we were able to find significant changes in not only the cellate, but also the fusiform neurons. And what this is telling us is that, in accordance with the previous data that the other researchers had shown, not only are there significant changes in behavioral aspects, but these neurons are also just a lot bigger in these vestibular nuclei upon the administration of this gentamicin. So our data here is telling us that if we do administrate gentamicin intranasally, there are morphological effects on neurons within these nuclei, within the brainstem. And so, although our project is still early on, it is showing good signs that our hypothesis will become true, and also based off of the metadata that, with this amount of administration, there is still ototoxic effects on the vestibular system as a whole. And we want to thank you for listening to our presentation today, and we hope you all have a good rest of your day.

intranasal gentamicin

vestibular nuclei

ototoxicity

neuron morphology

rat models