| 00:03 | Cellular Neuroscience lecture for. And we discussing glia, we just talked about |
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| 00:10 | functions of microglia and I'm not certain sharing the screen now. So let |
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| 00:18 | sure it is here. Mhm So again, you can click and watch |
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| 00:35 | video and these are the main functions microglia. We will spend some more |
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| 00:39 | talking about microglia. A little bit about asides where we talk about |
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| 00:45 | we already discussed how asides are very involved in the information control and processing |
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| 00:55 | the synopsis. This is pre synoptic , this is bossy tic terminal. |
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| 01:00 | they regulate the chemical content of the space. They regulate neurotransmitters as |
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| 01:08 | And by that is that they have ability to siphon off if there are |
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| 01:14 | abnormal increases in ionic concentrations, or there are increases in neurotransmitters. Astro |
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| 01:22 | will essentially facilitate the clearance of these concentrations by suctioning up and distributing that |
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| 01:34 | substance through its own extensive morphological tree also through its interconnections with other |
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| 01:44 | And that's important because you don't want have anyone given ion or anyone given |
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| 01:50 | increase for sustained period of time and network because that could mean hyperactivity, |
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| 01:58 | could mean essentially damage to that part the brain. Uh and it could |
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| 02:04 | short term damage with recovery or uh on what it is, it could |
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| 02:09 | longer term damage. Now, astrocytes involved in synaptic genesis or synapse formation |
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| 02:16 | synaptic plasticity and neurite outgrowth and retraction the formation of new dendritic spines and |
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| 02:23 | retraction of the dendritic spines. It's most abundant glial subtype and a lot |
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| 02:30 | times because it is wrapped around the neurons, neuron, one presynaptic |
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| 02:36 | two post synaptic and astrocyte wrapped around controlling the synaptic transmission. Here in |
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| 02:42 | communication, it's referred to as a synapse. So the synapse that has |
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| 02:48 | parts or tripartite snobs, this is morphology of ostracizes and they're, they're |
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| 02:58 | with the GFP uh fluorescent protein, fluorescent protein um and also tomato. |
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| 03:11 | tomato is gonna be something in red two separate adeno associated viruses constructs using |
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| 03:20 | racy specific the moer. Pretty It's basically a viral construct for uh |
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| 03:29 | specific promoter. And you can visualize cells then in several wavelengths and the |
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| 03:38 | of that is to see how abundant are. So anywhere you're seeing a |
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| 03:45 | signal here, you have astrocytes. you zoom in, you have these |
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| 03:52 | of astrocytes also may be thought of have some sort of a hub like |
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| 03:58 | . Sometimes neuronal networks also thought of hubli formations for example, if you |
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| 04:04 | here, is there any geometrical structure this network or is the structure activity |
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| 04:12 | based on the connectivity? So now we're zooming in to these astrocytes. |
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| 04:19 | here now you can understand the surface that one astrocytes can occupy and the |
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| 04:27 | for it to redistribute these abnormal rises the ionic concentrations or neurotransmitters and astrocyte |
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| 04:39 | is really complex because for a long , uh we were not that much |
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| 04:45 | in astrocytes. Uh We didn't think they had much to do with neuronal |
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| 04:52 | . And in general glia or most the 20th century was thought to have |
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| 04:58 | a supporting and insulating function rather than function and controlling synaptic activity or synaptic |
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| 05:07 | . And this gives you a perspective some of the methods that allow you |
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| 05:15 | study volume of the cell. And is a very complex cell to study |
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| 05:21 | it has quite a large volume in dimensions. It has a lot of |
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| 05:29 | of its processing. It has multiple of branching from primary to secondary tertiary |
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| 05:38 | and so on branches like in, trees or in bushes. And so |
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| 05:43 | do you approach and how do you it? And obviously now, since |
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| 05:47 | understand that these end processes have a to do with communication with other |
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| 05:56 | with communication with other ostracizes and also control of blood brain barrier. It's |
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| 06:04 | important for us to understand the three structure and the volume of these |
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| 06:10 | So this is a extra reading aside analysis if you're interested in general. |
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| 06:16 | it's not just for asides of this method of analysis can be applied |
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| 06:22 | other cells. But what are some the common methods? So you can |
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| 06:27 | a territory analysis from flat and cal images. Confocal imaging confocal microscopy, |
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| 06:36 | get pretty high resolution, you have fluorescent cell, the cell that is |
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| 06:43 | being stained or with a viral expression tagging this racy. So this astrocyte |
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| 06:49 | glowing against the background for example, it's flattened. So you take some |
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| 06:56 | of a two dimensional essentially measurement and try to derive the size of the |
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| 07:04 | that cell would occupy. So it maybe tell you something about the uh |
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| 07:14 | the diameter, the territory size, selma size, the SOMA territory |
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| 07:22 | the circularity round this number of major fractal dimension. OK. So this |
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| 07:29 | all information you can draw from If you look at the next image |
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| 07:35 | B, it's Shaw analysis and Shaw is specifically designed to study branching. |
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| 07:43 | in this case in Shaw analysis, have these rings and they're standardized. |
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| 07:49 | the distance between these rings, if use Shaw analysis in the nanoscale and |
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| 07:55 | micro scale or other scales, it's standardized the size between these rings. |
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| 08:03 | so typically the first ring is just to surround the SOMA of the |
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| 08:11 | And within this first ring, you're be able to count the primary branches |
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| 08:17 | the cell. So 12345 primary the second ring, the second ring |
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| 08:27 | now going to count the secondary And you're gonna say, OK, |
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| 08:35 | maybe you're gonna miss some of the that are not touching. There are |
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| 08:39 | algorithms that you can count branches in to still catch them or you may |
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| 08:46 | to discard it because of, you , some other reasons, scientific |
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| 08:50 | But here, instead of the primary , you're gonna be counting secondary |
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| 08:57 | 6789, 1011, 1213, And of course, we'll say, |
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| 09:03 | , different cells will have different distances , and in one cell you'll count |
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| 09:09 | as a secondary and in another cell still secondary, but you may count |
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| 09:14 | still as a primary. So how do you really account for? |
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| 09:18 | , that's why it's called standard deviation statistics and sample size. So once |
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| 09:24 | sample in a certain area or certain of glial cells, there's several |
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| 09:30 | Remember we just looked at uh uh different subtypes of neurons, but there |
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| 09:37 | different subtypes of glial cells too. you may find differences in their uh |
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| 09:44 | of branches. There's another uh method , it's called shown and ramification and |
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| 09:51 | . But in any case, this to determine the territory, this tries |
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| 09:55 | determine the branch and complexity. This a volume analysis. So it's called |
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| 10:04 | infiltration analysis. So you're looking at volume here, here, you're looking |
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| 10:12 | the territory volume. So you're still at the volume in three dimensions. |
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| 10:17 | then you're looking potentially at the closeness the South because what do you think |
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| 10:26 | closeness might be indicative of uh exactly they might be connected to each other |
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| 10:34 | that they're more likely communicating with each than the cells and the SOMA that |
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| 10:40 | outside of each other's branch territories. that's a yet another territory volume and |
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| 10:48 | analysis it's called. So this is to give you a a AAA an |
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| 10:54 | of how cell volumes and branching are studied on a, on a not |
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| 11:01 | on a reconstruction of the cells and at their morphology, but looking at |
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| 11:06 | volume, looking at the three really looking at the proximity of the |
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| 11:13 | because it could be indicative of their and functionality. Ost toys uh also |
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| 11:24 | involved in the formation of the blood barrier together with endothelial cells. And |
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| 11:31 | cells contain these tight junctions and abnormal release of cytokines, inflammation, |
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| 11:40 | due to infection, bacterial viral infection compromise the openings or these uh checkpoints |
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| 11:51 | the filial cells, the T they can become leaky and a lot |
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| 11:55 | substances can start crossing over into the . The same happens with aging inflammation |
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| 12:04 | and cytokines are sort of a um one with another. But during |
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| 12:13 | our blood brain barrier also gets So older people potentially have more infections |
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| 12:22 | come from the blood into the brain get infected more easily. Uh CD |
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| 12:30 | T cells, for example, can through blood brain barrier. And so |
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| 12:37 | is an immune response by CD four cells where they can cross into the |
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| 12:44 | . And this blood brain barrier is a barrier for pharmaceutical drugs. |
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| 12:51 | if you want to add an effective drug in the blood, which most |
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| 12:56 | the drugs are taken as pills or injected into the bloodstream. If you |
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| 13:02 | them effectively to get into the they better have qualities that will cross |
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| 13:07 | blood brain barrier, they will be small or maybe they will be |
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| 13:13 | So uh fat soluble in order to through the membranes of the cells |
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| 13:22 | this is again uh the fact that we look at the brain, uh |
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| 13:29 | cells that are shown here, the and uh uh uh and microglia that |
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| 13:37 | talked about, they contribute to the homeostasis of of the brain. So |
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| 13:45 | have microglia in orange, right? what they, what they do is |
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| 13:56 | are some processes that they oversee astrocytes shown in blue and we already talked |
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| 14:04 | how they control synaptogenesis. So the formation uh that happens during homeostasis. |
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| 14:15 | the green cells that are capable to . And this is young blood brain |
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| 14:23 | with fight uh junction sealed, Um You also have these little green |
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| 14:34 | that are, you know, monocytes can cross through the blood brain |
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| 14:39 | In case there's an inflammatory uh event as an infection or a trauma to |
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| 14:46 | brain in older organisms and older What happens is this blood brain barrier |
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| 14:57 | getting degraded as it starts getting degraded substances, including these green monocytes can |
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| 15:06 | crossing through the blood brain barrier. case you have an inflammatory isn't. |
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| 15:14 | this becomes leaking during the aging process then you have microglia a very fast |
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| 15:23 | reactive inflammatory stimuli. But what happens with aging microglia is also not as |
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| 15:32 | and it's also not as mobile, also not also not as good as |
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| 15:38 | up and contributing to the injury and processes or repair processes following injury. |
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| 15:48 | another point of interest, neurodevelopment, and microglia interactions. So let's look |
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| 16:01 | this wheel of how astrocytes and microglia , neuronal cell death survival and |
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| 16:11 | So we have, first of all the left in A E and |
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| 16:16 | we have suggested interactions. This is new science that suggests certain interactions and |
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| 16:24 | with these interactions between micro and uh Astros. You also on the left |
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| 16:33 | de and F which is evidence So that's something that has been |
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| 16:41 | What has been observed is that micro and ostracized will contribute to regulation of |
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| 16:49 | number of synapses. The number of actually, uh once they have the |
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| 16:58 | of synopsis, they'll control synaptogenesis and control the development of neural circuit. |
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| 17:08 | will also contribute to the development of vessels, blood vessels, angiogenesis, |
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| 17:16 | of blood vessels and vascularization of the MS. So that is what's |
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| 17:23 | what is suggested is that they play role in neuronal cell death, survival |
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| 17:29 | differentiation, neuronal morphogenesis and in So, they could be contributing to |
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| 17:41 | following uh light damage. So, you have demyelination, that is not |
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| 17:48 | a part of the chronic disease or genetic mutation. Uh in part, |
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| 17:57 | myelin can be restored and the suggestive for restoration or for, for the |
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| 18:06 | uh for these glial cells to contribute the restoration of myelin or remyelination if |
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| 18:12 | may, which is really, really . So you would say that in |
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| 18:17 | like we just looked at um multiple where you have demyelination as an autoimmune |
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| 18:26 | , you would want to have some of a drug that is also a |
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| 18:31 | , not a drug that just stops , but also a drug that facilitates |
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| 18:38 | cells and the cellular mechanisms that could rebuild the myelin back around the damaged |
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| 18:44 | mileage sheets and neurons. This is example of astrocyte and microglia interactions. |
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| 18:54 | have neural circuit formation. We're already uh are familiar with that. And |
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| 19:02 | together with oocytes and these cells could communicating with each other. Glia also |
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| 19:08 | to the chemical and synaptic transmission as part of the tripartite synapse and |
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| 19:14 | So what happens to those dendritic What if they, but off, |
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| 19:19 | if they get lost? What if is new regrowth? What if there |
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| 19:24 | ? So microglia comes in and contributes this process of synaptogenesis and control the |
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| 19:30 | of synopsis as they form. And the synopsis are dying and pieces of |
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| 19:35 | membrane, let's say like little leaves the tree are getting pruned and breaking |
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| 19:40 | and flying off micro, we are to engulf them and to clean up |
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| 19:45 | this process. So in, in what you have is in the last |
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| 19:55 | , you have microglia. And this a, an example from retina and |
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| 20:02 | shows that in retina, you have specific pattern of vascularization in the retina |
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| 20:09 | with obviously certain areas that certain branching of these blood vessels and in between |
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| 20:20 | are the astrocytes. And what you here is obviously, there will be |
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| 20:26 | part of the blood brain barrier of . That's why they're inter intertwined with |
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| 20:31 | , with the blood vessels. And you ablate, if you essentially destroy |
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| 20:38 | blade, and there's some chemical methods you can apply a chemical that will |
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| 20:43 | blade microglia, what it does? changes the vascular arrangement and changes the |
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| 20:50 | , geometrical structures and densities of, the cells. So again, it's |
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| 20:58 | important and essentially helping vascularization and not uh ostracized but microglia and presence of |
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| 21:08 | together with ostracizes is important. Seems be for the structure of what we |
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| 21:13 | about of the blood brain barrier and connections between Astros and blood brain |
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| 21:19 | Let's go back a little bit and about homeostasis. It's keeping the brain |
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| 21:27 | and neural function within a certain dynamic , which means that uh if there |
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| 21:34 | an increase in concentration of certain it gets taken up and gets redistributed |
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| 21:43 | , that's keeping up the balance of chemical and synaptic activity within a certain |
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| 21:50 | dynamic range. Now, you have a neuron that is breaking up and |
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| 21:57 | talked about how um microglia will rush in case of the injury and start |
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| 22:06 | and cleaning up the dying neurons, example, but ostracize will also do |
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| 22:14 | . So astrocytes will actually synchronize astrocytes have thy ttic functions and they will |
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| 22:26 | synchronize with microglia in cleaning up the . Ok. And you can see |
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| 22:34 | the bulk of that cell is still bulk of that cell is still gonna |
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| 22:40 | engulfed by microglia. And notice also happens to the microglia shape as it |
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| 22:51 | a dead neuron. It becomes a boy like it loses its nice structure |
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| 23:01 | the processes. Remember, we saw extending these processes, it becomes more |
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| 23:07 | an amoeba shaped c once it engulfs dead neuron and then what happens to |
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| 23:16 | essentially dead microglia to that dead microglia chewed up by asides. So it's |
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| 23:28 | , it's a, it's an intricate . And so where does it |
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| 23:31 | Right? What happens to who, eats ostracizes? What happens? Do |
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| 23:36 | com com commit suicide? What You know, uh they didn't explain |
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| 23:42 | in this, in this figure And you know, for some of these |
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| 23:46 | , we're just uncovering these processes So the other interesting part of it |
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| 23:53 | uh CND it's uh the microglia that been primed by the substance LP S |
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| 24:07 | , you know, microglia that have like a meat boy like shade have |
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| 24:15 | the dead neuron. And what they doing is they start releasing adenosine TRS |
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| 24:25 | . So remember that A TP is only the energy molecule, but it's |
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| 24:30 | a neurotransmitter. So as they start a TB and that a TRS fate |
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| 24:39 | have a TP receptors, those are P two Y one R receptors. |
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| 24:46 | , a TP binding to these receptors ostracizes to release more glutamine. We'll |
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| 24:57 | about synaptic transmission. Um uh Next , sorry, next lecture. But |
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| 25:07 | thing in that tripartite synapse that troys is that they control the amount of |
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| 25:16 | that is available to neurons. And they actually start releasing glutamate and start |
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| 25:26 | glutamate pre curses that neurons can use these neurons can become a lot more |
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| 25:35 | and can cause hyper excitability in So now you have a process where |
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| 25:40 | have uh an inflammation, a signal microglia that has responded to an infection |
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| 25:49 | starts putting out a TP that a causes overproduction of glutamate availability of glutamine |
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| 25:58 | glutamate and hyperexcitability in neurons. So , inflammation, infection, traumatic brain |
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| 26:08 | with the brain that essentially leading to through uh through the processes that are |
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| 26:16 | by glia. Indeed, what we is another feature that we will study |
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| 26:26 | next lecture is that astrocytes are interconnected other uh astrocytes through electrical synapses that |
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| 26:36 | called gap junctions. And there gab or GB junctional comp coupling. This |
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| 26:45 | is two proteins connects in on one process and connects them in another astrocyte |
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| 26:54 | that build this continuous gap, this channel between ostracizes. And what it |
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| 27:03 | here is that again, if you the number or you add late, |
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| 27:09 | rid of microglia, you reduce the of gap junctions that form between |
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| 27:19 | So this is an example of where are not only controlling synaptogenesis and the |
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| 27:29 | what we typically call chemical synopsis and and those chemical synopsis. But in |
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| 27:36 | case, microglia controlled the number of synopsis or gap junction synopsis in other |
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| 27:46 | in this case and in ostracizes. right. So this ends this particular |
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| 27:55 | and I'd like to just share. , it's very short slides of information |
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| 28:02 | is really, uh interesting for me I think for everybody al also. |
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| 28:16 | see. Then Glenda. There we . Ok. So brand new off |
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| 28:27 | process as, as they, as say. And, oh, it's |
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| 28:31 | little bit much better here. It's little bit blurry. It's probably better |
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| 28:35 | your screens if you have it. you ever, you know, one |
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| 28:41 | that you probably heard is a build of lactate or build up of lactic |
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| 28:50 | , uh during exercise. And it thought to be, you know, |
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| 28:55 | and you need to, to clear the muscle, softer, intense |
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| 29:01 | So, what I've learned is I , and I mentioned to you before |
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| 29:06 | that the brain is only about 1.5 2.5% of your total body mass, |
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| 29:13 | it uses 20% of its energy, body energy. So everything that gets |
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| 29:20 | that can get turned into from energy into Pyruvate and then processed uh through |
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| 29:28 | cycle and the mitochondria to produce a . That's, you know, so |
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| 29:33 | dietary sugar, uh intake, protein , right? Uh And then, |
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| 29:43 | know, I've also been wondering that you exercise, you also feel better |
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| 29:53 | , not just physically, you can hurt yourself physically most of the time |
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| 29:58 | , you don't, but mentally you uh better also. And so this |
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| 30:04 | a very interesting article that discusses basically ability these are referred to MC |
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| 30:15 | they're like uh shuttles and these they essentially shut all the lactate into |
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| 30:29 | , into the neurons from astrocytes. microglia and neurons can produce energy by |
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| 30:40 | these molecules and being shuttled into essentially source of energy and A TP. |
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| 30:51 | this article discusses that about 11% of lactate goes into the brain and gets |
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| 31:04 | essentially in the cycle, which I necessarily want you to know all of |
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| 31:10 | details. But in the cycle, it now can not only produce more |
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| 31:21 | but also allow for neurons to produce of neurotransmitter. So maybe that's why |
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| 31:32 | somebody is exercising, OK. These , these A NLS shuttles neuron |
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| 31:44 | neuron, lactate shuttles. Uh They for the transport of lactate into neurons |
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| 31:56 | allow for neurons to have more energy produce more neurotransmitter. And doesn't that |
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| 32:05 | sense that you are not only more , potentially following the exercising because you |
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| 32:11 | woken up and you're energized to your brain is energized. And because |
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| 32:19 | brain is energized, your neurotransmission is also. So it's so it's interesting |
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| 32:28 | that have to do with lactate that emerging. And this lactate metabolism is |
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| 32:37 | intricately involved in the circle. And keep looking at the circle probably from |
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| 32:44 | different papers. The Thai locate metabolism some other molecule like top protein or |
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| 32:54 | infection to neuro inflammation which ties to . And the reason why I showed |
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| 33:03 | the circle is like, OK, , well, you can basically insert |
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| 33:09 | favorite molecule here, maybe insert your cell or leave ostracized in many |
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| 33:17 | in many uh conditions and paradigms or my gli here. And that leads |
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| 33:23 | abnormal neuro inflammation and that leads to neurological disorders. And so when we |
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| 33:31 | about Alzheimer's disease, it's the brain flames. It's inflamed brain. When |
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| 33:37 | talk about epilepsy, there's inflammation. we talk about infection by COVID-19, |
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| 33:43 | inflammation. When we talk about traumatic injury, there's inflammation, autoimmune |
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| 33:51 | there's inflammation again in many instances. for many interpretations, and you'll see |
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| 34:00 | quite a few articles that we use semester, this is gonna be uh |
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| 34:05 | something that stands at the sort of as a tying bond or stands at |
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| 34:12 | crossroads of neurodegenerative diseases and potentially allows the comorbidities to be sequestered. A |
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| 34:23 | that allows for other diseases to rear ugly head as a comorbidity to already |
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| 34:30 | disorder. All right. So this our lecture for material. I'm gonna |
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| 34:44 | the recording |
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