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Effect of maternal SSRI antidepressants on p11 expression in the fetal brain: a mouse model

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Effect of maternal SSRI antidepressants on p11 expression in the fetal brain: a mouse model

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Effect of Maternal SSRI Antidepressants on P11 Expression in the Fetal Brain;
a Mouse Model

Jennifer R. King MD
1
, Juan C. Velasquez
2
, Alexandre Bonnin PhD
2

1
Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, Keck
School of Medicine, University of Southern California, Los Angeles, California
2
Zilkha Neurogenetic Institute and Dept of Cell and Neurobiology, Keck School of
Medicine, Los Angeles, California

Degree: Master of Science in Clinical, Biomedical, and Translational Investigations
Degree conferral month: December 2015

2

Table of Contents

Abstract --------------------------------------------------------------------------------------------- 3

Introduction ----------------------------------------------------------------------------------------- 4

Methods --------------------------------------------------------------------------------------------- 6

Results ----------------------------------------------------------------------------------------------- 9

Discussion ----------------------------------------------------------------------------------------- 11

Figures --------------------------------------------------------------------------------------------- 13

References ----------------------------------------------------------------------------------------- 16

3

Abstract

Background: Fetal exposure to maternal SSRIs has been associated with increased risk of
adverse neurodevelopmental outcomes in the offspring. SSRIs target the 5-HT system,
which plays critical modulatory roles in fetal brain development. The protein p11
(s100a10) interacts with the 5-HT1B/D (htr1b/d) serotonin (5-HT) receptors, regulating
their localization to the cell surface. 5-HT signaling through these receptors modulates
fetal brain axonal circuit formation. SSRI therapy has been shown to indirectly regulate
p11 levels in the adult brain.
Objectives: To determine 1) whether p11 is expressed in the fetal mouse brain, 2)
whether chronic maternal SSRI exposure affects p11 expression
Methods: Citalopram hydrobromide (CIT) was administered to pregnant mice
(20mg/kg/day) in the drinking water from embryonic day (E)8 to E17. Control mice
received regular drinking water. At E17, fetal brains were harvested. A subset of fetal
brains from the control group were sectioned and stained with anti-p11 and anti-5-HT
antibodies. A subset of fetal brains from the treatment group was used to determine tissue
concentrations of CIT using High Pressure Liquid Chromatography (HPLC). The
remaining fetal brains from both groups were dissected into frontal cortex, thalamus, and
hindbrain regions. Total proteins were extracted from each region and western blots were
performed to estimate p11 tissue levels.
Results: Immunohistochemical staining shows that p11 protein is expressed in the fetal
brain at E17. Most interestingly, p11 is present in thalamic neurons and in
thalamocortical axons. HPLC measures reveal that maternally-administered oral CIT
accumulates in the fetal brain at E17. Western blot analyses show that P11 protein
expression is significantly decreased by 45.1 +/- 5.5% after in utero CIT exposure
compared to untreated controls (95% confidence interval -58.6 to -31.6, p=0.0002) in the
fetal thalamus, but not cortex or hindbrain.
Conclusions: These findings reveal differential regulation of p11 expression in the fetal
brain as a result of chronic maternal SSRI antidepressant exposure. This may constitute a
novel molecular mechanism by which exposure to SSRIs disrupts fetal 5-HT signaling,
leading to long-term cognitive and behavioral abnormalities.

4

Introduction

The prevalence of major depressive disorders (MDD) in pregnancy is
approximately 13% (1). Selective serotonin reuptake inhibitor (SSRI) antidepressants
remain the mainstay of treatment, despite an unclear safety profile in pregnancy (2).
Although SSRI use may relieve symptoms of depression in pregnancy and ultimately lead
to improved pregnancy outcomes, potential risks to the fetus has made both providers
reluctant to prescribe them and pregnant women reluctant to accept them. Consequently,
the use of SSRIs for depression during pregnancy remains a therapeutic challenge.
The use of SSRIs during pregnancy is associated with increased risk of adverse
neurodevelopmental outcomes in the offspring (3). Epidemiologic studies suggest that the
use of SSRIs during pregnancy may have long-term consequences, such as increased risk
of autism spectrum disorders and postnatal language learning deficits (4-6). Timing of
exposure appears critical, with the highest risk after exposure to SSRIs during the first
trimester (5,6). A better understanding of the potential impact of these drugs on fetal
brain development is needed.
Serotonin (5-HT) signaling provides important modulation of histogenic
processes in the fetal brain, such as cell proliferation, migration, and axonal circuit
formation (7). Since SSRIs specifically inhibit the 5-HT transporter function and can
cross the human placenta, they could alter 5-HT availability in the fetal brain. Therefore,
fetal brain exposure to SSRIs during these periods could have profound consequences.
Specifically, fetal brain exposure to SSRIs is likely to affect thalamocortical axonal
(TCA) circuit formation, a process exquisitely sensitive to disruptions of 5-HT signaling
(8,9). Manipulation of 5-HT signaling through the 5-HT1B/1D receptors in utero has
been shown to alter TCA guidance and pathway formation in the fetal forebrain (9). In
addition, even without altering fetal brain levels of 5-HT, the SSRI citalopram can
directly affect the response of thalamic axons to guidance cues in vitro, suggesting
alterations in TCA pathway formation in vivo (10). Any effect of SSRIs on the
development of this particular pathway is critically important because thalamocortical
circuits underlie social, emotional, and cognitive higher functions and disruption of their
normal function can lead to life-long brain dysfunction (11-14).
In the adult brain, the SSRI citalopram (CIT) increases neuronal expression of
p11 (s100a10), a member of the S100 family of proteins with a well-established role in
trafficking of transmembrane proteins to the cell surface (15,16) It has been shown that
p11 regulates the cell surface translocation of the Gi-coupled 5-HT1B/1D receptors by
forming molecular complexes (17). P11 has been implicated as a potential mediator in the
pathophysiology of MDD in humans and in depression-like states in rodent models (18).
This association is demonstrated by evidence of decreased p11 mRNA expression
measured post-mortem in brains of MDD patients who committed suicide and genetic
rodent models of depression (19,20). Additional support has been generated by studies
showing p11 knockout mice exhibit depression-like behaviors whereas p11
overexpressing mice display antidepressant-like responses in behavioral paradigms
measuring depression-like states (17,19) Furthermore, Svenningson et al. showed that
p11 increases the concentration of 5-HT1B receptors at the synapse, thereby increasing
the overall efficiency of 5-HT signaling (19). This interaction appears to have a key role

5

in regulating an individual’s susceptibility to depression and the response to SSRI
therapy. Despite the increasing understanding of the role of p11 in the adult brain,
nothing is known about its role in fetal brain development or the molecular mechanisms
by which treatment with SSRIs during pregnancy affects fetal neurodevelopment.
In the fetal brain, a precise level of 5-HT signaling through the 5-HT1B/1D
receptors is critical for normal TCA pathway formation. If maternally-administered
SSRIs reach the fetal brain, they could functionally impact the p11/5-HT1B/1D
molecular pathway, altering downstream 5-HT signaling and 5-HT-dependent TCA
pathway formation. Our objectives were to determine 1) whether p11 is expressed in the
fetal mouse brain, 2) whether maternal SSRI administration effects its expression.

6

Methods

Animals and chronic maternal citalopram exposure

Experiments were conducted using timed-pregnant CD-1 mice obtained from
Charles-River laboratories (San Diego, CA). Mice were housed 3-5 per cage with ad
libitum access to food and water. Mice received 20mg/kg/day Citalopram hydrobromide
(TCI America, C2370) from embryonic (E) day 8 to E17 (treatment group). CIT was
administered orally in drinking water containing 1% sucrose to mask the taste of the
drug. The drug concentration in the drinking water (0.13g/L CIT) was determined from
the average daily water consumption and the average body weight per mouse to achieve
the target dose. The control group consisted of mice exposed to regular drinking water
with 1% sucrose. CIT and control water solutions were monitored throughout the study
and were replaced 5 days after the start of the treatment. Mice were randomly assigned
to the treatment or control group (n = 4 dams / group). At E17, mice were anaesthetized
through inhalation of isoflurane gas (Western Medical Supply) and sacrificed by cervical
dislocation. The uterus was immediately dissected and embryos from both treatment and
control groups were harvested and placed on ice in 1x phosphate buffered saline (PBS).
Maternal and fetal brains were dissected into frontal cortex, thalamus, and hindbrain
regions (Figure 3B), weighed, snap-frozen in liquid nitrogen and stored at -80°C until
use. Regions from 2 embryos per dam were pooled prior to storage. The position of each
embryo in the uterus was recorded and a small tail biopsy was collected for determination
of sex by SRY genotyping. Procedures were approved by the USC Institutional Animal
Care and Use Committee.

Measure of fetal brain CIT tissue concentration

Maternal and fetal blood sera and fetal brains were harvested at E17 from timed-
pregnant mice exposed to CIT from E8 to E17 in drinking water (20mg/kg). Extractions
were performed on 3-5 embryos harvested from 2-3 dams. Tissue samples were
sonicated in 0.2M perchloric acid containing 500mM D-mannitol, 100uM EDTA-2Na,
and 100ng/mL isoproterenol as internal standard. Samples were spun at 20,000g for 15
min at 4C following a 30-minute incubation on ice. The supernatant was removed
and stored at -80C. Pellets were used for total protein quantification. Concentrations of
CIT and DCIT were determined by High Pressure Liquid Chromatography coupled to
a Fluorescent Detector (HPLC-FLD). HPLC-FLD analysis was performed using an
Eicom 700 system (Eicom Corporation, Kyoto, Japan) with a Shimatzu RF-20AX
fluorescence detector set at 250 nm (excitation) and 325 (emission) wavelengths
(Shimadzu, Kyoto, Japan). An Eicompak SC-30DS C
18
reversed-phase column packed
with 3-µm silica particles (3.0 x 100-mm I.D.) was used as the analytical column. A 10-
µL aliquot of extracted sample was injected onto the column and eluted with a mobile
phase of 10mM KH
2
PO
4
/Acetonitrile (3:1 v/v) (pH= 4.0 with 1M phosphoric acid), at a
flow rate of 500µL/min.

7

P11 immunohistochemistry in the fetal brain

A subset of E17 fetal brains from the control group were dissected in ice cold
PBS and immediately transferred to 4% paraformaldehyde for incubation at 4°C for 24
hours. The fetal brains were then incubated at 4°C in increasing amounts of sucrose
(10%, 20%, 30% dissolved in PBS) for 24 hours each. After the last incubation, the fetal
brains were embedded in cryomolds on dry ice using tissue tek (VWR, 25608-930) and
stored at -80°C until sectioned. On the evening prior to sectioning, the embedded fetal
brains were removed from -80°C and allowed to warm to -20°C. The entire rostro-caudal
extent of each fetal brain was sectioned into 20 µm-thick coronal sections. Sections were
stored at -80°C until immunohistochemical analysis.
Sections were permeabilized with PBS containing 0.1% Triton X-100 and 2%
fetal bovine serum and incubated overnight at room temperature with primary antibodies
to p11 (1:100 goat anti-S100A10, R&D Systems) and 5-HT (1:1000 rabbit anti-5HT,
Sigma). Slides were then washed in PBS with 0.1% Triton X-100 (PBST) before
applying secondary antibody. Incubation with secondary antibodies (1:800 anti-goat
HRP and 1:800 anti-rabbit Rhodamine Red, Jackson ImmunoResearch Laboratories)
occurred at room temperature for 2 hours in the dark. Slides were again washed in PBST
prior to amplification. For amplification, slides were incubated in Tyramide Signal
Amplification-Fluorescein solution (1:50; Perkin Elmer, NEL701A001KT) for 10
minutes at room temperature in the dark. A final series of washes with PBST was
performed and the slides were mounted using Prolong Gold with DAPI (to visualize
nuclei; Life Technologies, P36931). Images were acquired with a Zeiss AxioCam MRm
camera (Carl Zeiss, USA) using Zeiss AxioVision 4.8.2 software (Zeiss).

Measure of p11 protein expression in the fetal brain

Unless otherwise noted, all reagents were purchased from Sigma. Pre-dissected
and pooled (2 embryos per region) E17 fetal mice brain samples were removed from the -
80°C freezer for both treatment and control groups. Total proteins were extracted by
sonication in lysis buffer containing: 50mM hepes pH7.4, 2mM EGTA, 10mM sodium
orthovanadate, 30mM sodium fluoride, 40mM beta-glycerol phosphate, 1% Triton X-
100, and complete mini protease inhibitor cocktail EDTA-free (1 tablet/10ml; Roche).
Protein concentrations were measured by Bradford protein assay according to the
manufacturer’s instruction (Biorad). All samples were separated on NuPAGE Novex 4-
12% Bis-Tris protein gels (Life Technologies), transferred to polyvinylidine fluoride
membrane, and blocked in 0.5% bovine serum albumin in Tris-buffered Saline + 0.1%
Tween 20. Western blots were incubated at 4°C overnight in primary antibody to p11
(anti-S100A10 1:2000, R&D Systems) and GAPDH (anti-GAPDH, 1:1000, Abcam).
Membranes were washed in Tris-buffered Saline + 0.1% Tween 20 and incubated with
horseradish peroxidase-conjugated secondary antibody for 1 hour at room temperature
(rabbit anti-goat 1:1000; R&D Systems). Blots were incubated in enhanced
chemiluminescent reagent (ECL; GE Healthcare Life Sciences); blots chemiluminescence
was measured using Image Station 4000MM Pro (Carestream) using Carestream
Molecular Imaging version 5.07.22 software. P11 protein tissue concentration was

8

estimated by densitometric analysis. Values were normalized to GAPDH protein level
measured in the same samples to correct for total protein loading differences.

Statistical analysis

Mean normalized chemiluminescence and standard error of the mean were
calculated for each brain region (cortex, thalamus, hindbrain) in control and treatment
groups. For each individual region, comparisons between treatment and control means
were made by unpaired Student t test. Results were considered statistically significant if
two-sided p-value was <0.05.

9

Results

P11 expression in the fetal brain

The Allen Developing Mouse Brain Atlas provides an extensive database and
rapid mean for interrogating gene expression in the fetal brain (21). Based on in situ
hybridization, it shows that p11 mRNA is expressed in the developing cortex, thalamus,
and hindbrain (Fig. 1A) (21). In particular, p11 mRNA is present in the developing
thalamus at E18 in patterns overlapping with 5-HT1B receptor (htr1b), serotonin
transporter (Slc6a4), and the TCA marker netrin-G1a (netG1a; Fig. 1B-D) (21). P11 and
5-HT1B receptor mRNA are also present in the thalamus at postnatal (P) day 4 (Figure
1E-F) and later (data not shown) (21).
The presence of p11 transcripts in the fetal forebrain led us to investigate p11
protein expression pattern. Immunohistochemical staining shows that p11 protein is
detected in the cortex, hypothalamus, and hindbrain (Fig. 2A) at E17. Most interestingly,
p11 protein is detected in neuronal cell bodies located in the ventral posteriolateral
thalamic nucleus (Fig. 1D). Based on anatomical location, these p11+ cells correspond to
neurons that give rise to the thalamocortical axonal pathway. Consistent with this
observation, p11 immunoreactivity is detected in thalamocortical axons coursing through
the internal capsule (Fig. 1E).

In utero CIT exposure

CIT exposure was previously shown to affect p11 expression in the adult brain
(18), but nothing is known about its effect in the fetal brain. In utero, a direct effect of
CIT on p11 requires that the drug reach the fetal brain. We first tested this possibility by
measuring CIT tissue concentration in the brain of fetuses harvested from mothers
chronically exposed to the drug. CIT was administered orally, through the drinking water
to pregnant dams from E8 to E17. The dose chosen for oral exposure (20mg/kg/day)
leads to a steady state concentration of CIT in the maternal serum of 117.94 ng/mL (n=2).
Tissue concentration of CIT and its primary metabolite D-CIT measured by HPLC reveal
that this dosing of maternally-administered oral CIT leads to accumulation of the drug
and its metabolite in the fetal brain at E17 (Figure 3A).

Effect of CIT on fetal p11 expression

In order to test if CIT exposure in utero affects the expression of p11 in the fetal
brain, we used western blotting to estimate p11 protein tissue concentration in forebrain
regions where p11 immunoreactivity was detected (Fig. 2). The frontal cortex, thalamus
and hindbrain were harvested at E17 from embryos whose mothers were exposed to
regular drinking water, or water containing CIT (20 mg/kg/day) from E8 to E17 (Figure
3B). Western blot analyses show differential effects of in utero CIT exposure on p11
protein expression in the various fetal forebrain regions (Figure 3C-D). P11 protein
expression in the fetal thalamus is significantly decreased by 45.1 +/- 5.5% after in utero
CIT exposure compared to untreated controls (95% confidence interval -58.6 to -31.6,

10

p=0.0002). In contrast, maternal exposure to CIT has no significant effect on p11 protein
expression in the fetal cortex or hindbrain. In the fetal cortex, p11 protein expression
decreased by 10.0 +/- 40.3% (95% confidence interval -90.0 to 89.8, p =0.9981), while in
the hindbrain p11 protein expression increased by 45.1 +/- 47.0% (95% confidence
interval -59.6 to 149.8, p = 0.3600).

11

Discussion

In the adult brain, p11 recently emerged as an important component of 5-HT
signaling. It was shown to form molecular complexes with 5-HT1B/1D receptors and
regulate their translocation to the cell surface, providing direct modulation of signaling
through these receptors. The role of p11 in fetal brain development is unknown. Since 5-
HT1B/1D receptors induce 5-HT modulation of important neurogenic processes, we
investigated p11 expression in the fetal brain in relation to 5-HT1B/1D receptors
expression pattern.
Our results show that p11 protein is present in discrete regions of the fetal mouse
brain at E17. Importantly, p11 is detected in several regions where 5-HT1B/1D receptors
are prenatally expressed, including the cortex, hindbrain and thalamus (22). The
expression of p11 in fetal thalamic neurons and thalamocortical axons is particularly
striking and overlaps with 5-HT1B/1D receptors expression in both compartments (Fig. 1
and 9,22). The actual co-localization of p11 and 5-HT1B/1D receptors, at the protein
level, and the exact identity of p11+ neurons in the thalamus is under investigation. This
will be tested by co-immunostaining with p11 and 5-HT1B/1D antibodies on E17 fetal
brain sections as well as co-labeling with markers of specific thalamic nuclei like
VMAT2 and SERT.
The possibility that p11 forms molecular complexes with 5-HT1B/1D receptors in
fetal thalamic neurons and axons is currently being tested by co-immunoprecipitation and
western blot. An interaction between p11 and 5-HT1B/1D receptors in thalamic neurons
and axons would suggest that p11 contributes to the development of this axonal pathway.
Indeed, 5-HT1B/1D receptors have critical developmental roles in TCA pathway
formation (8,9). These G
i
-protein coupled 5-HT receptors are transiently expressed by
thalamic neurons, from E12 to early postnatal stages (~P10) (22,23). Prenatally, 5-
HT1B/1D modulation of intracellular cAMP concentration in thalamic neurons changes
the chemotactic response of their growing axons to the guidance cue netrin-1 (9) and the
direct in vivo manipulation of 5-HT1B/1D receptors gene expression in fetal thalamic
neurons, by in utero electroporation, leads to abnormal TCA pathfinding (9) i.e.
decreased expression of 5-HT1B/1D receptors leads to an expanded ventro-lateral shift of
the TCA pathway in the internal capsule, while an increase leads to a restricted dorso-
medial shift (9). In summary, 5-HT signaling through 5-HT1B/1D receptors modulates
intracellular cAMP concentrations in thalamic neurons and exerts a critical influence on
TCA pathway formation. Therefore, if fetal brain p11 acts similarly to adult brain p11 by
regulating the cell surface translocation of 5-HT1B/1D receptors in fetal thalamic
neurons, it could contribute to a key modulation of TCA pathway formation.
In the adult brain, the SSRI CIT increases neuronal expression of p11, which
affects the cell surface translocation of 5-HT1B/1D receptors (17). Our observations that
p11 is expressed in the fetal brain in overlapping patterns with 5-HT1B/1D receptors
raise the possibility that maternal CIT administration might affect p11 expression in the
fetal brain as it does in the adult brain. Our results show that during pregnancy,
maternally-administered CIT reaches the fetal brain and produces complex patterns of
change in p11 expression. In particular, it induces a significant decrease of p11
expression in the fetal thalamus. If p11 endogenously regulates 5-HT1B/1D receptors

12

plasma membrane translocation in the fetal brain, decreasing or increasing its expression
in fetal thalamic neurons is expected to alter 5-HT signaling and impact TCA circuit
formation in a manner similar to the direct manipulation of 5-HT1B/1D receptors
expression.
Therefore, the CIT-mediated decrease of p11 expression observed here is
expected to decrease 5-HT1B/1D receptors signaling ability to negatively regulate
intracellular cAMP levels in thalamic neurons. During the fetal period, this will affect the
chemotactic response of TCAs to guidance cues such as netrin-1 (9), which would result
in a ventro-lateral shift or expansion of growing TCAs in the internal capsule. This
possibility is being investigated by studying TCA pathway topography in subsets of E17
embryos that were exposed to CIT in utero.
Investigations are ongoing to better elucidate the downstream effects of the CIT-
mediated decrease of p11 protein expression on 5-HT1B/1D receptor translocation and
signaling and the impact on TCA pathway formation.

13

Figures

Figure 1: P11 mRNA expression in the developing brain. (A) P11 mRNA is expressed in
the thalamus (Thal; red arrow), cortex (Ctx), and hindbrain (Hind) at E18. (B, C, D) In
the thalamus, 5-HT1B (Htr1b) receptor, netrin-G1a (NetG1a) and SERT (Slc6a4) mRNA
are detected in overlapping patterns at embryonic day E18. (E, F) P11 and 5-HT1B
mRNA are expressed in the thalamus (red arrow) in overlapping patterns at postnatal day
P4. In situ hybridization data from the Allen Developing Mouse Brain Atlas.

14

Figure 2: P11 protein expression in the E17 fetal brain. (A-C) Co-labeling with p11 and
5-HT antibodies on coronal sections show p11+ thalamocortical axons passing through
the internal capsule (IC, red arrows; A), dorsal to 5-HT+ axons running through the
medial forebrain bundle (B). (C) Overlay of P11 and 5-HT immunostainings. Scale bars
represent 200 µm. (D) Close-up view of p11+ thalamocortical axons coursing through the
internal capsule. Scale bar = 20 µm. (E, F) p11+ cell bodies are present in ventral
posteriolateral nucleus (VPL) of the thalamus (E) and the ventral hypothalamus (Hyp, F).
Scale bars represent 20 µm. Ctx = cortex, Thal = thalamus, Hip = hippocampus, Mfb =
medial forebrain bundle.

15

Figure 3: Effect of in utero exposure to CIT on p11 expression in the fetal brain. (A)
Chronic exposure of timed-pregnant mice from E8 to E17 to CIT in drinking water
(20mg/kg/day) leads to accumulation of the drug (CIT) and its metabolite (DCIT) in the
fetal brain. (B) Schematic representation of the fetal brain dissected out at E17 for
subsequent p11 expression analysis: Ctx = cortex (frontal half), Thal = thalamus, Hind =
hindbrain. (C) p11 protein concentration was estimated by western blot in regions
described in (B) in maternally untreated and maternal CIT-exposed (20mg/kg/day from
E8-E17) fetal mouse brains. GAPDH was used as a loading control. The placenta (Plac)
strongly expresses p11 and was used as a positive control. (D) Western blot densitometric
analyses show that chronic exposure of the fetus to CIT leads to a significant decrease in
p11 protein concentration in the fetal thalamus (***p=0.0002 versus untreated by
Student’s t test). Each column represents mean + SEM (n = 4 dams with 2 pooled
embryos per dam).

16

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2002;22:886–900.

Abstract (if available)

Abstract Background: Fetal exposure to maternal SSRIs has been associated with increased risk of adverse neurodevelopmental outcomes in the offspring. SSRIs target the 5-HT system, which plays critical modulatory roles in fetal brain development. The protein p11 (s100a10) interacts with the 5-HT1B/D (htr1b/d) serotonin (5-HT) receptors, regulating their localization to the cell surface. 5-HT signaling through these receptors modulates fetal brain axonal circuit formation. SSRI therapy has been shown to indirectly regulate p11 levels in the adult brain. ❧ Objectives: To determine 1) whether p11 is expressed in the fetal mouse brain, 2) whether chronic maternal SSRI exposure affects p11 expression. ❧ Methods: Citalopram hydrobromide (CIT) was administered to pregnant mice (20mg/kg/day) in the drinking water from embryonic day (E)8 to E17. Control mice received regular drinking water. At E17, fetal brains were harvested. A subset of fetal brains from the control group were sectioned and stained with anti-p11 and anti-5-HT antibodies. A subset of fetal brains from the treatment group was used to determine tissue concentrations of CIT using High Pressure Liquid Chromatography (HPLC). The remaining fetal brains from both groups were dissected into frontal cortex, thalamus, and hindbrain regions. Total proteins were extracted from each region and western blots were performed to estimate p11 tissue levels. ❧ Results: Immunohistochemical staining shows that p11 protein is expressed in the fetal brain at E17. Most interestingly, p11 is present in thalamic neurons and in thalamocortical axons. HPLC measures reveal that maternally-administered oral CIT accumulates in the fetal brain at E17. Western blot analyses show that P11 protein expression is significantly decreased by 45.1 +/− 5.5% after in utero CIT exposure compared to untreated controls (95% confidence interval −58.6 to −31.6, p=0.0002) in the fetal thalamus, but not cortex or hindbrain. ❧ Conclusions: These findings reveal differential regulation of p11 expression in the fetal brain as a result of chronic maternal SSRI antidepressant exposure. This may constitute a novel molecular mechanism by which exposure to SSRIs disrupts fetal 5-HT signaling, leading to long-term cognitive and behavioral abnormalities.

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Asset Metadata

Creator King, Jennifer Renae (author)

Core Title Effect of maternal SSRI antidepressants on p11 expression in the fetal brain: a mouse model

School Keck School of Medicine

Degree Master of Science

Degree Program Clinical, Biomedical and Translational Investigations

Publication Date 09/03/2015

Defense Date 09/03/2015

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag antidepressants,OAI-PMH Harvest,p11,Pregnancy,serotonin,SSRI

Format application/pdf (imt)

Language English

Contributor Electronically uploaded by the author (provenance)

Advisor Bonnin, Alexandre (committee chair), Azen, Stanley (committee member), Lee, Richard H. (committee member)

Creator Email jennifrk@usc.edu,jennyrenaeking@gmail.com

Permanent Link (DOI) https://doi.org/10.25549/usctheses-c40-175587

Unique identifier UC11275270

Identifier etd-KingJennif-3873.pdf (filename),usctheses-c40-175587 (legacy record id)

Legacy Identifier etd-KingJennif-3873.pdf

Dmrecord 175587

Document Type Thesis

Format application/pdf (imt)

Rights King, Jennifer Renae

Type texts

Source University of Southern California (contributing entity), University of Southern California Dissertations and Theses (collection)

Access Conditions The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the a...

Repository Name University of Southern California Digital Library

Repository Location USC Digital Library, University of Southern California, University Park Campus MC 2810, 3434 South Grand Avenue, 2nd Floor, Los Angeles, California 90089-2810, USA