Brain Flashcards

(119 cards)

1
Q

Cytokines/cytotoxic mediators in the brain come from where?

A

Activated microglia can release them, (ROS and nitrogen species) –> apoptosis and loss of OL precurosors, dysregulation (failing to myelinate axons)

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2
Q

What is the knowledge gap

A

Molecular mechanisms eliciting inflammation thru placenta-fetal-brain axis are unknown

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3
Q

Rat brain is considered as developed as human newborn how many days postnatal

A

P10-12

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4
Q

Neurogenesis is what and starts when in rat vs human

A

rat: G0 - 10
human: 0 - 12 weeks
STEP 1: Neurogenesis: This is the earliest step, where neural stem cells in the ventricular zone differentiate into neurons.

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5
Q

Astrocyte and OLs start to generate after..

A

the beginnning of neurogenesis, and gliogenesi continues postnatally in both humans and rats

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6
Q

Astrogenesis is what step and what is it?

A

3RD STEP
following neurogenesis, radial glial cells differentiate into astrocytes, which support neurons and maintain the brain’s environment.

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7
Q

Microglial invasion is what step and what is it?

A

SECOND
Support immune protection and help shape developing neural circuits
Come from progenitor cells in the yolk sac
Start colonising the rat brain slightly after G10 continue to peak postnatally

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8
Q

What marks the 3rd trimester?

A

Beginning of synaptogenesis, astrogenesis, myelination (20-40 weeks human, G20-P12 rats)

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9
Q

When do OLs start developing ?

A

OLs start developing prenatally, maturating from pre-OLs to immature OLs from mid-gestation to the end of gestation

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10
Q

When does myelination occur?

A

prenatally and postnatally in humans but occurs postnatally in rodents

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11
Q

What is myelination and what step?

A

4th
Myelination: Oligodendrocytes wrap axons in myelin to speed up electrical signaling. In humans, myelination

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12
Q

What are the mechanisms linking maternal and fetal responses to brain damage?

A

Increased proinflammatory cytokines in the brain:
1) activated microglia (critical in synaptic plasticity/myelination)/astrocytes
- activation of these = neuronal migration processes, neuronal death, damage surrounding axons etc
2) maturation and death of OLs
3) axonal loss or death of neurons, cytoskeletal damage, neurotoxicity
Innate immune molecules may alter directly or indirectly some neuronal processes
Overall, cerebral dysconnectivity associated with hypomyelination

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13
Q

The nature and severity of brain injuries depend on…

A

The timing, intensity and nature of inflammatory insult

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14
Q

First trimester insults associated with?

A

brain maldevelopments

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15
Q

Second trimester insults associated with?

A

periventricular WM injury (periventricular leukomalacia)

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16
Q

Third trimester insults?

A

cortical and deep grey matter damage

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17
Q

Altered myelination is partially due to what?

A

impaired OL maturation

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18
Q

Effect of IL1b on brain?

A

ACTIVATE astrocyte and microglia cells
(and then these release more cytokines)
directly (i.e. by neurotoxicity) or indirectly (i.e. by modulating axonal guidance proteins and synaptogenesis) inhibit cell proliferation and neurogenesis, cause neuronal death, delayed myelination and disrupt neuroglial fibre tract growth and synaptic connections, which can lead to permanent alterations of brain connectivity

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19
Q

Pillars of ASD?

A
  1. repetitive/stereotype behavior
  2. impairments in communication / social behavior
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20
Q

ASD affects how many children?

A

1/60

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21
Q

Among a cohort of ex-preterm ASD human subjects,

A
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22
Q

Brain development in utero explain

A

Week 3 - ectoderm thickens and forms neural plate –> neural groove
Week 4 - neural tube, (become the brain and spinal cord)
Week 8 - most structures in place, wweek 11 - has a similar shape to what it will be like at birth

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23
Q

Give examples of studies that have highlighted proinflammatory effect of androgen in the brain?

A

A study using finasteride (drug inhibits the formation of DHT) in a PPA-induced autism rat model. Neuroprotective effects, biochemical, histopathological, and behavioral analyses.

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24
Q

What are OLs?

A

Glial cells that support and maintain integrity of axons and neuronal connectivity within the central nervous system

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25
Another study which shows protective effect of flutamide on OLs?
The study showed that flutamide prevented both the direct toxicity of testosterone and its ability to exacerbate excitotoxic damage induced by glutamate receptors in cultured oligodendrocytes
26
Is there a conflict in the literature of T effects on the brain - neuroprotective/ neurotoxic?
Yes, some studies indicate that T low levels being protective and high levels being detrimental.
27
In a study, blocking T conversion to estradiol did what?
Increased damage, estradiol as a neuroprotective factor against cerebral ischemia
28
What happens to plasma levels of LH and T after acute flutamide tx?
Increase, reduces negative feedback on HPA
29
In our study what is the effect of flutamide on hormonal balances?
More androgen = more conversion of A into E in brain tissue by aromatase
30
How does estradiol regulate OLs?
E delays the exit of OPC from the cell cycle, so in our model the inc of CC1+ OLs may have resulted from estradiol prolonging the cell cycle of OPCs, thereby increasing the pool of mature OLs in flut/gbs group
31
Why did GBS cause enlargement of LV?
Decrease of CC-1 oligodendrocytes in forebrain whtie matter = shrinkage of surrounding brain tissue due to a loss of mature OLs and subsequent demylination (Smaller bundles of axons and underdeveloped neuronal connections)
32
What is often used to treat cerebral edema by reducing inflammation?
glucocorticoids (adverse effects like brain atrophy)
33
What other effects on GBS could brain have?
Neuronal loss, cortical thickness,
34
Is there evidence of androgen contributing to vulnerability in females and how?
Yes by androgenization of females
35
Astrocytes in development ?
Derived from radial glial cells, beginning around E14 in rodents. from the subventricular zone of the lateral ventricles (also OLs)
36
Microglia in development?
Derived from yolk sac progenitors, migrating into the brain around E9
37
OLs in development
Derived from oligodendrocyte precursor cells (OPCs), starting around E14 and maturing postnatally.
38
Fronto-parietal tract
passes through EC attention, working memory
39
Thalamo-corticla tract
passes through EC sensory integration and processing
40
Amygdalo-hippocampal tract
passes through EC social behaviors and emotion
41
is iba-1 for activated microglia? explain more
activated - amoeboid shape, thicker retracted processes M1 - proinflammatory -> proinflammatory cytokines, ROS M2 - anti inflammatoyr (a bit less amoeboid than M1, more branches) -> BDNF, IL10, TGFb, clear debris wound healing
42
FINNN why did cc-1 increase with flutamide?
LH and T plasma levels increase flutamide, as an androgen receptor antagonist, reduces the negative feedback that testosterone and other androgens have on the hypothalamic-pituitary-gonadal axis higher conversions of androgens into estrogens in brain tissues by aromatase estradiol delays the exit of OPCs from the cell cycle [37]. Thus, the observed increase in CC-1+ oligodendrocytes may result from estradiol’s role in prolonging the cell cycle of OPCs, thereby increasing the pool of mature oligodendrocytes in flutamide/GBS groups ORR Indirect Mechanism (Placenta-Mediated Reduction in Inflammation) Flutamide also reduces placental inflammation, as you show — leading to: Lower IL-1β, TNF-α, and neutrophil EVs reaching the fetal brain. Less activation of microglia and reduced oxidative or cytokine-driven toxicity. 🔁 How would this impact CC1⁺ cells? Inflammation (especially IL-1β and oxidative stress) is known to: Kill OPCs or arrest their differentiation Trigger myelin damage So reduced inflammatory signaling would allow: Preservation of the OPC pool Unimpeded differentiation into mature OLs
43
what about LV , why. did it increase
The observed decrease in CC-1+ oligodendrocytes in the forebrain white matter likely resulted in the observed enlargement of lateral ventricles in GBS-infected groups This increase in size may reflect the atrophy or shrinkage of surrounding brain tissue due to a loss of mature oligodendrocytes and subsequent dysmyelination likely be a result of the underdevelopment of neuronal connections, resulting in smaller bundles of axons within the forebrain white matter
44
why was microglia not reduced in GBS induced ca?
previous studies in our lab noted a decreased in females in microglia but not males in another stuyd, microglia depleted rats spent less time in open arms of EPM --> more anxiety, same as what our mdoel showed GBS III showed dec microglia in CC could have looked at microglial morphology, spacing, clustering as opposed to jsut density
45
what else are microglia importnat in?
neuronal migration, prenatal brain circuit shaping, myelination, synpatogenesis During neurogenesis, microglia influence the survival, differentiation, and apoptosis of neuronal precursor cells through the secretion of brain-derived neurotrophic factor and neurotoxic factors In postnatal development, microglia facilitate synaptic formation and maturation via synaptic pruning The involvement of microglia in long-term synaptic plasticity serves as the foundation for learning and memory processes
46
which cell type produces myelin
schwann cell
47
why arent microglia activated in our model?
Time point matters - this is at P50, microglia could have already turned to a less active state, we could have missed earlier peaks
48
how can il1b inhibit neurogenesis
Directly: By damaging neurons through its toxic effects. Indirectly: By disrupting critical developmental processes like axon growth and synapse formation.
49
why white matter?
axonal wiring anomalies inducing dysconnective/ dysfunctional brain networks7–12
50
Explain IL1ra study?
Human recombinant interleukin-1 receptor antagonist (IL-1Ra) is an FDA-approved therapeutic option to treat rheumatoid arthritis IL-1 blockade using IL-1Ra is currently tested in a phase I/II pilot trial to prevent human preterm lung and brain injuries Approval for several pediatric inflammatory conditions and being actually tested in phase I/II therapeutic trial in the premature population
51
what are the effects of GBS on neuron
neuronal apoptosis reported in our model of gbs CA at P5. neuronal cell differentiation, synaptic connectivity and neuronal survival altering the WM connectivity via neuronal death, axonal degeneration
52
is there a sex diff in microglia ?
Sex differences in microglia number and function are evident early in the neonatal brain. yes more activated in male in utero and less activated in male adulthood (Females mroe) BUT after the
53
microglia what age they colonize in rats?
Microglia initially colonize the brain early in development (embryonic day (E) 9-10 in rodents). During this time and into the postnatal weeks, microglia have an important role in forming neural circuits by initiating synapse formation, pruning aberrant synapses, and phagocytosing naturally dying cells.
54
what's so imp about microglia?
function may affect WM connectivity and perturb NDD process such as OL maturation in development: During this time and into the postnatal weeks, microglia have an important role in forming neural circuits by initiating synapse formation, pruning aberrant synapses, and phagocytosing naturally dying cells.
55
why didnt you see activation of microglia?
outcome of functional damage of microglia, p50 - dont remain activated until that day
56
explain microglia and damp
Microglia and macrophages detect dead and dying cells via released “find-me” signals such as high-mobility group box protein 1 (HMGB1) and the presence of “eat-me” signals such as phosphatidylserine on the outer leaflet of cell membranes. (23) (released by dying cells, or microglia themselves) HMGB1 translocates from the nucleus to the cytosol and is released extracellularly. (25,28) When located extracellularly, HMGB1 acts as a damage-associated molecular pattern (DAMP), also called an alarmin, where it mediates neuroinflammatory responses in stroke Toll-like receptors (TLRs), triggering the translocation and activation of nuclear factor kappa B (NF-κB) to the nucleus to induce gene expression and subsequent proinflammatory cytokine
57
what did other studies look atin our lab ?
MBP analyses were focused on that specific distance from the Bregma based on previously published results in addition to MRI findings of enlarged lateral ventricles in GBS-exposed versus control males
58
what have they found in ASD in humans?
. A meta-analyses of region of interest (ROI) brain volumes showed larger total brain (TBV), intracranial (ICV), cerebral hemispheres, cerebellum, and caudate volumes as well as smaller corpus callosum volumes in ASD subjects compared to healthy control
59
explain how dysonnectivity is associated with ASD?
Hence, microglial activation by pro-inflammatory cytokines can damage neurons and glial cells, leading to WM injuries or interferences with synaptic connections, and brain dysconnectivity. Astrogliosis and microglial activation can alter neuronal migration processes, induce neuronal death, stop oligodendrocyte maturation, damage surrounding axons and/or trigger a loss of synaptic connections, leading to cerebral dysconnectivity associated with hypomyelination (Figure
60
why is the white matter vulenrable to inflammatory insults near end of gestation? esp since myelination occurs postnatally in rats?
Ongoing Myelination Process: While myelination begins postnatally, the precursor cells (oligodendrocyte progenitor cells) are still present and actively developing at the end of gestation. These immature oligodendrocytes are more susceptible to damage from inflammation Blood-Brain Barrier Development: The blood-brain barrier (BBB) in rats, like in humans, is still immature at the end of gestation. An underdeveloped BBB allows immune cells and inflammatory cytokines to cross into the brain more easily, making the white matter more vulnerable to inflammation.
61
why was it thought that inflammatory insults cause the fetall BBB to become more permeable?
cytokines interacting with tight junction proteins activated microglia release MMPs degrade extracellulr matrix/ tight junction proteins enzymes repsonsible for degredation of extracellular matrix (matrix metalloproteinases)
62
but why is it in our case that the fetal BBB becomes leass m
an increase in claudin 5 expressin found in brains post mortem ASD, BBB is important in delivery of neurotrophic faactors from placenta to brain - ensure proper development of the brain connectome - defects in these factors are linked to ASD
63
can exosomes pass the BBB? how?
transytosis radiolabeled exosomes. The exosomes are labeled with 125I using the chloramine-T method. After labeling, they are purified using an Illustra NAP-5 column and characterized. In the subsequent experiment, the radiolabeled exosomes are injected into the mice through the jugular vein, and samples are collected from the brain and serum to assess exosome uptake at various time points. The radioactivity in these samples is measured to evaluate the levels of exosomes in different tissues.
64
in summary - dysregulated IR --> alter white matter connectivity in the brain how?
neuronal death, axonal degeneration, OL defects, impairing microglia (which are critical cells invovled in plasticity, myelination), loss of synaptic connections,
65
how do cytokines cause nueronal death?
activated microglia and astrocyte can produce cytokines --> can release ROS cytokines can lead to an imblanace in glutamate signaling --> excitotoxicity mitochondrial dysfunction, activation of apoptotic pathways/cell death pathways cytokines can also disrupt the BBB
66
why we see this effect on BBB becoming less permeable in GBS?
- Dec albumin staining - Inc claudin 5 (tight junction protein critical component of the BBB, claudin 5 highly expressed in endothelia cells) - Such drop of permeability of BBB might interfere with the systemic transfer from the placenta to the brain of key neurotrophic factors – such as the insulin-like growth factor 1 – involved in the development of the brain connectome whose defects are present in
67
following release of cytokines in placenta and fetal bloodstream, neurotoxic effects on fetal brain...? how
- inc glutamate production and reduce its clearance - excitotoxicity (by elevating glutamate production), inducing neuronal necrosis, axonal loss - activation of glial cells astrocyte (BBB impairment, glutamate clearance, pro inflammatory cytokine sec) microglia (proinflammatory cytokine prod, M1 or M2 polarization) - necroptosis/apoptosi, death of OLs -myelination and diffuse white matter brain injuries
68
why would microglia be reduced?
they are imp in synaptogenesis - Hence, this decreased density of microglial cells in GBS-exposed rats might affect some neurodevelopmental key processes such as postnatal synaptic pruning, failing to remove or promote effective synapses (Pierre et al., 2017). Moreover, the reduced number of microglial cells might affect OL functions, by affecting the production of MBP component, forming the myelin sheath along with proteolipid protein
69
what else do we see in ASD brains?
altered neuronal and axonal netwroks
70
microglia effect what
WM connectivity and synaptic plasticity, and may perturb neurodevelopmental processes such as pre-OL maturation
71
abnormalities in the external capsule why are they relevant to ASD?
Abnormalities in the external capsule are relevant to ASD, as fronto-temporal connections are crucial for regulating behaviors often affected in ASD, including anxiety, sensory integration, and others. EC- EC connects neural pathways from frontal lobe -> temporal lobe eg fronto-parietal (attention, working memory) and thalamo-cortical (sensory integration processing) These pathways integral for functions related to social beahiovr, emotion. -often disrupted in ASD amygadol-hippocampal tract for social behaviors/emotion) are passing through the external capsule in rodents 
72
proinflammatory cytokines cause direct or indirect brain injury?
Proinflammatory cytokines cause both direct and indirect brain injury. Directly, cytokines like IL-1β and TNF-α lead to neuronal death, delayed myelination, and apoptosis of oligodendrocytes. Indirectly, they activate microglia and astrocytes, which release more cytokines and free radicals, damaging brain cells and disrupting white matter structure and neuronal connectivity.
73
Insults during the first trimester are often linked to structural abnormalities
neural tube defects
74
later insults are more commonly associated with
psychiatric conditions, including ASD
75
what happens to plasma levels of LH and T after flutamide tx?
F blocks AR, reducing negative feedback on HPA axis, inc LH and T secretion
76
How might flutamide affect estrogen levels in the brain?
By increasing upstream androgen levels like testosterone, more may be converted to estrogens via aromatase in brain tissue.
77
What is estradiol's effect on oligodendrocyte progenitor cells (OPCs)?
Estradiol delays OPC exit from the cell cycle, possibly increasing the pool of mature oligodendrocytes.
78
What could explain the increase in CC-1+ oligodendrocytes in the flutamide/GBS group?
Elevated estradiol may have prolonged OPC cycling, resulting in more mature oligodendrocytes.
79
What is a limitation of this study regarding hormone effects? paper 2
It does not distinguish the specific roles of androgens versus estrogens; future work could use aromatase inhibitors like letrozole.
79
Besides inflammation, what other factor might contribute to reduced CC-1+ cells and white matter abnormalities?
Impaired transport of endocrine molecules like growth hormone (GH) and insulin-like growth factor 1 (IGF-1) to the fetal brain.
80
In a poly I:C MIA model using IL-6 knockout mice, what happened to GH and IGF-1 expression in placentas?
GH and IGF-1 expression decreased, likely due to loss of IL-6-mediated JAK/STAT3 signaling affecting the GH/IGF axis.
81
What roles does IGF-1 play during development?
IGF-1 supports placental efficiency, trophoblast function, fetal growth, neurogenesis, myelination, maturation, and differentiation.
82
What developmental condition is associated with altered IGF levels?
Intrauterine growth restriction (IUGR), which is linked to altered microglia and white matter injury.
83
Did you measure GH or IGF in your GBS model?
Not directly. However, prior literature (e.g., Hsiao and Patterson 2012) supports reduced IGF in MIA models, and the IUGR phenotype in our model aligns with this.
84
Why is thyroid hormone (TH) homeostasis important for brain development?
TH regulates critical processes such as oligodendrocyte differentiation and myelination. Disruption can impair axon insulation and lead to neurodevelopmental delays.
85
What is the connection between hypothyroidism and neurodevelopmental outcomes?
Hypothyroidism, particularly during pregnancy, is associated with delayed myelination and cognitive impairments in offspring due to impaired oligodendrocyte maturation.
86
What are the main TH transporters into the brain, and where are they expressed?
MCT8 and OATP1c1 are TH transporters expressed at the blood-brain barrier, especially in endothelial cells and pericytes. They enable T3 and T4 to cross into the brain.
87
What happens to TH transporter expression during inflammation?
In rodent models, inflammation (e.g., via LPS) significantly downregulates MCT8 and OATP1c1 expression at the BBB, which could impair TH entry into the brain.
88
Why didnt you see changes in Iba-1?
May be a matter of timing, area etc. during fetal and neonatal stages of development, or morphological changes?
89
How could MIA impact TH delivery to the fetal brain?
If GBS-induced MIA downregulates TH transporters like LPS does, it may reduce fetal brain access to T3 and T4, contributing to white matter damage and developmental delay.
90
why did flutamide increase microglia density?
neonatal brain, with males having higher microglial density compared to females during this period Interestingly, this effect is reversed in adulthood, where females display a more activated microglial state compared to males.
91
Doesnt a lot of literature say that systemic inflammation disrupts the BBB through structural damage, enhanced cellular traffic and increased permeability?
yes but many of these studies focus on the early postnatal or adult BBB
92
but does GBS induced MIA cause a more leaky BBB?
no, less leaky These results could be explained by MIA accelerating BBB maturation via the upregulation of tight junction proteins, which strengthen the barrier and limit the passage of molecules.This may have implications for the transport across the BBB from the placenta of trophic factors discussed earlier such as IGF and TH
93
Which proteins were upregulated in brain EVs
cathepsin G, olfactomedin 4, and MPO, because of their high specificity to neutrophils. Neutrophils are scarce in the brain under normal conditions and were not identified to be present in our model (Bergeron et al. 2013; Girard S 2010). Thus, the presence of these neutrophil-associated proteins in brain-derived EVs despite the absence of neutrophils in the brain is intriguing, suggesting that these originate from outside the brain. “Using CytoFLEX, we can measure how many EVs in the fetal brain are both neutrophil-derived and carry IL-1, and see if that links to brain injury or behavior. ONI imaging will let us see exactly where these EVs go — whether they’ve been taken up by brain cells like microglia, or just sit near blood vessels. Together, these tools will help us test whether immune EVs from outside the brain, like from the placenta or fetal blood, are crossing into the brain and driving inflammation and white matter injury — even without neutrophils physically entering the brain.”
94
Do neutrophils secrete EVs?
yes, high expression of granule proteins. promote bacterial aggregation through integrin-independent interactions and actin remodelling
95
IL-1b is associated with _____ while TNF-a induces_____
neuronal death and delayed myelination apoptosis of oligodendrocytes Both cytokines can also exacerbate neurotoxicity by increasing glutamate production, leading to excitotoxic death
96
FIRS can lead to and impact microglia, astrocyte, OL, neurons??
microglia: activated astrocyte: activated OL: maturation arrest or death neuron: axonal loss or death of neurons, cytoskeletal damage, neurotoxicity
97
Justify the EC
We chose the external capsule as a primary region of interest because it integrates several ASD-relevant neural circuits—including fronto-parietal and thalamo-cortical pathways, as well as limbic projections like the amygdala-hippocampus tract. These pathways are critical for social behavior, sensory integration, and emotional processing—all domains affected in our model. Importantly, the EC is a vulnerable white matter tract during the perinatal window, making it a compelling site for studying early-life inflammation-induced injury.
98
justify WM instead of neuron?
WMI is the most common form of brain injury in preterm infants and has been strongly associated with cognitive and behavioral outcomes, including ASD
99
should you have looked at neurons?
others report neuronal apopotosis p5, absolutely, we did not directly address neuronal loss or cortical and basal gray nuclei thickness.
100
Why are glial cells more affected by inflammation than neurons in the perinatal period?
Glial cells (especially microglia and oligodendrocytes) are immune-responsive and developmentally active during late gestation and early postnatal life. They’re primed to react to cytokines like IL-1β and TNF-α, making them early targets in inflammation.
101
What are neurons doing during late gestation and early postnatal development?
Neurons have largely completed migration and are starting synaptogenesis, axonal targeting, and early dendritic growth. Their activity is still immature and depends on glial support for connectivity and metabolic stability.
102
What specific developmental processes are glia involved in that impact neurons?
Oligodendrocytes: Myelinate axons for proper signal transmission Astrocytes: Regulate the extracellular environment, glutamate clearance, and provide trophic support Microglia: Prune synapses and mediate immune responses
103
How can glial dysfunction lead to neuronal disruption without killing neurons?
Impaired glia disrupt myelination, cytokine balance, and synaptic pruning, which can lead to abnormal connectivity, delayed maturation, or functional impairment in neurons—without causing cell death.
104
Why did your study focus on glia rather than neurons?
Because glial cells are the first to respond to inflammation and are central to white matter development. Neuronal effects may occur later as downstream consequences of early glial dysfunction.
105
Does flutamide rescue suggest androgens affect oligodendrocyte differentiation, survival, or both?
Our results show that GBS exposure in males led to a reduction in CC1+ mature oligodendrocytes in the external capsule, while Olig2+ cell numbers (olig projenitor cells) remained unchanged. This suggests that oligodendrocyte progenitors were still present, but failed to differentiate fully. The fact that flutamide restored CC1+ cell density without changing Olig2+ counts supports the idea that androgens impair oligodendrocyte differentiation, rather than survival or proliferation
106
Do hormones affect aromatase?
endometriosis, inflammation increases local estrogen production via increased aromatase In the brain, however, especially during development, inflammation may suppress aromatase, reducing neuroprotective estrogen synthesis.
107
TH why is it important?
- hypothyroidism and neurodevelopmental delays in offspring - delayed myelination due to impaired oligodendrocyte differentiation, resulting in fewer myelinated axons - mRNA levels of both MCT8 and OATP1c1 were significantly decreased in brain vessels upon LPS administration in endothelial cells and pericytes
108
GH / IGF why is it important?
MIA model using POLY IC and IL-6 knockout mice, GH and IGF-1 expression were decreased in placentas - IGF plays a key role in overall placental efficiency and regulation of trophoblast function, as well as being a key regulator of fetal growth - important role in processes such as neurogenesis, myelination, maturation, and differentiation - altered IGF levels are linked to IUGR, highlighted in our model of GBS-induced MIA in the offspring, where IUGR persisted until adolescence
109
what other behavioral tests
1. Ultrasonic Vocalizations, Assesses early communication abilities — relevant to ASD core symptoms. Rat pups emit USVs when isolated from the dam. Altered number or frequency suggests disrupted social communication 2. Marble Burying Test – Juvenile to Adult, Measures repetitive behaviors, another ASD hallmark. More marbles buried may indicate perseverative or compulsive-like behavior; 3. Pre-Pulse Inhibition (PPI) – P20–Adult, Tests sensorimotor gating, often impaired in neuropsychiatric disorders. how well the brain gates and processes incoming sensory input. Poor gating is seen in: ASD
110
why did you do OF at P20?
Assess baseline locomotion and anxiety-like behavior early in life P20 in rats corresponds roughly to early childhood in humans — the prepubertal period when core motor and sensory functions are maturing Low hormonal influence: Prepubertal rats haven’t yet undergone the pubertal testosterone surge, so effects observed are more likely due to perinatal neuroinflammation
111
why social interactions at P40?
Evaluate mature social behavior P50 aligns with late adolescence to young adulthood in rats — the period when: The prefrontal cortex, amygdala, and limbic circuits are more fully developed. Sex hormones have surged and shaped brain circuits, particularly in males. ilke sniffing, grooming, play-fighting — become robust and reliable around
112
why EPM at p50?
1. Maturation of Anxiety Circuits By P50, key brain areas governing anxiety and emotional reactivity — like the amygdala, prefrontal cortex, hippocampus, and hypothalamus — are fully developed. Earlier ages (e.g., P20) are less reliable for EPM because rats at that stage: May be overly exploratory (i.e., high open-arm time regardless of anxiety), Or not sufficiently mobile to produce meaningful contrasts. Captures persistent emotional dysregulation from fetal inflammatory insults
113
Why it's important to space behavioral tests
1. Avoid confounding effects of prior tests Behavioral testing can induce stress, fatigue, or habituation to the environment. These effects can alter baseline activity, anxiety levels, or learning/memory in subsequent tests. 2. Prevent behavioral interference Repeated handling or exposure to similar stimuli can blunt responses due to desensitization or learning. 3. Allow for recovery and baseline restoration Animals need time to recover physiologically and behaviorally, especially after stress-sensitive tasks.
114
how did you choose the specific points in the brain? bregma? what sections?
Second, this level shows early signs of white matter vulnerability in perinatal inflammation models, including oligodendrocyte lineage changes, as previously reported by MJ such as the hippocampal CA1-CA3 fields, dentate gyrus, corpus callosum, he choice of this bregma level also ensures consistency across animals
115
AR localization in brain
Expression is region-specific, cell-type-specific amygdala, hippocampus, cortex, POA show strong AR expression, especialy in males other areas like cerebellu, thalamus, cortex less
116
AR which cell types
neurons, glial cells, non genomic: dendrite, axons - rapid signalling, ion channel, nuerotransmitter release,
117
ok so if external capsule doesnt have so much AR, then why is CC1 affected there?
“In our model, the placenta is the critical site of AR action. The improvements we see in fetal brain development following flutamide are likely driven by placenta-to-brain communication, rather than direct AR signaling within the brain white matter.”
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can flutamide act in placenta AND fetal brain?
yes in addition to blocking placental AR, flutamide may also act directly in the fetal brain, where AR is expressed in neurons and glial processes. Even if expression is relatively low in white matter regions like the external capsule, extranuclear AR or axonal AR may mediate local inflammatory or developmental signaling. Blocking this could contribute to improved oligodendrocyte maturation and reduced neuroinflammation. Thus, while the placenta is the key amplifier in our model, direct fetal brain AR blockade likely acts synergistically