# Autistic-like behavioral effects of prenatal stress in the FMR1-KO mouse model of fragile X syndrome

Valeria Petroni, Enejda Subashi, Marika Premoli, Markus Wöhr, Wim E. Crusio, Valérie Lemaire, Susanna Pietropaolo

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Valeria Petroni, Enejda Subashi, Marika Premoli, Markus Wöhr, Wim E. Crusio, et al., Autistic-like behavioral effects of prenatal stress in the FMR1-KO mouse model of fragile X syndrome. FENS Annual Meeting 2022, Jul 2022, Paris, France. . [hal-03834348](https://hal HAL Id:)

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Distributed under a Creative Commons Attribution 4.0 International License
# AUTISTIC-LIKE BEHAVIORAL EFFECTS OF PRENATAL STRESS IN THE FMR1-KO MOUSE MODEL OF FRAGILE X SYNDROME

Valeria Petroni¹§, Enejda Subashi¹§, Marika Premoli², Markus Wöhr³,⁴,⁵,⁶, Wim E Crusio¹, Valerie Lemaire¹# and Susanna Pietropaolo¹#*

¹ INCIA, CNRS, France, ² University of Brescia, Italy, ³,⁴ KU Leuven, Belgium, ⁵,⁶ Philipps-University of Marburg, Germany

## BACKGROUND

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Fragile X Syndrome (FXS) is the most common heritable form of mental retardation and the main monogenic cause of autism spectrum disorder (ASD). FXS is due to a mutation in the X-linked FMR1 human gene consisting in more than 200 CGG repetitions leading to the absence of FMRP protein and is characterized by motor, cognitive and social alterations, mostly overlapping with autism spectrum disorder behavioral phenotypes.

FXS behavioral phenotype can be critically modulated by environmental factors e.g., stress exposure, both in terms of its severity and of the timing of appearance

## AIMS

**Study 1:** Evaluate the short-term effects of the prenatal exposure to unpredictable chronic stress on the behavioral phenotype of juveniles of both sexes in the Fmr1 knock-out (KO) mouse model of FXS, in order to assess whether the prenatal stress could advance and/or exacerbate the behavioral phenotype of Fmr1-KO offspring.

**Study 2:** Evaluate the long-term effects of prenatal exposure to unpredictable chronic stress during the last prenatal week on the FXS- and ASD-like behavioral phenotype of the Fmr1-KO model to assess the stability of the stress effects in Fmr1 mutant mice, extending their behavioral characterization during aging.

## STUDY 1: SHORT-TERM EFFECTS - JUVENILES

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* 45 males (n=9-15 for stress condition) and 48 females (n=12 for stress condition).

* Unpredictable mild stress → restrain stress (3 sessions 30-min day 1) and overnight housing with wet bedding; sawdust and cage changes (3 sessions day 2), overnight housing with novel glass black beads.

* Behavioral tests (7-8 weeks): Open Field, Y-Maze, Social Interaction, Ultrasonic vocalizations

## STUDY 2: LONG-TERM EFFECTS - ADULTS AND OLD

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* 38 males (n=8-10 for stress condition) tested at 3 months (Adults).

* 31 surviving animals: n=8 for each stress condition) tested again at 18 months (Old).

* Same stress procedure as in study 1 → *Unpredictable mild stress*

* Behavioral tests: Elevated Plus Maze, Open Field, Y-Maze, Social Interaction, Ultrasonic vocalizations

## METHODS:

♀ BREEDERS (Fmr1 1/2 dams)

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## RESULTS:

### Behavioral phenotype

### Ultrasonic communication

### Ultrasonic classification

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**We observed:**

* Mutants: 1. ♀ Locomotion at both ages

2. ♂ Affiliate behavior at both ages

* Stress: 1. ♀ Anxiety and locomotion at adulthood

2. Hyperactivity (KO and WT) at aging

3. Cognitive deficit at both ages KO (♂ old)

4. ♀ Affiliate behavior at adulthood

**We observed:**

* Mutants: No effects

* Stress: 1. ♂ Duration of ultrasonic calls in old mice

**We observed:**

* Mutants: Qualitative alterations of ultrasonic calls in adults KO (♂ complex calls)

* Stress: 1. ♀ The percentage of flat calls in old mice (KO and WT)

2. ♂ The percentage of complex calls in adults and old mice (KO and WT)

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Petroni et al., *Frontiers -Under review.* Long-term behavioral effects of prenatal stress in the Fmr1-KO mouse model for Fragile X syndrome

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## METHODS:

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## RESULTS:

### Behavioral phenotype

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### Ultrasonic communication

### Ultrasonic classification

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**We observed:**

* Mutants: ♀ HET females affiliation behavior

* Stress: 2. Cognitive deficit in Y maze only in males

3. ♀ Affiliation behavior in WT males and females

4. ♀ Locomotion in females (HET and WT)

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**We observed:**

* Mutants: ♀ Number and duration of USVs in HET

females

* Stress: No selective effect

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**We observed:**

* Mutants: Qualitative alterations of USVs (♂ complex calls) in HET females

* Stress: No selective effect

Petroni et al., 2022, *Scientific Reports*. Autistic-like behavioral effects of prenatal stress in juvenile Fmr1 mice: the relevance of sex differences and gene-environment interactions

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## CONCLUSIONS-STUDY 1 (SHORT-TERM EFFECTS):

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* Stress induced the cognitive deficits only in Fmr1-KO males (deficit in Y maze at juvenile age)

* In females stress attenuated the Fmr1-KO phenotype because of its effects on locomotion, SI and USVs in WT mice

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Stress effects on FXS-phenotype are present only in the cognitive domain and in males. These effects are stable (adult and old mice) - Stress behavioral effects on locomotion, SI and USVs appear only as long-term effects → Gene-environment interactions play a major role in modulating the behavioral FXS-like phenotype of Fmr1-KO mice

## CONCLUSIONS-STUDY 2 (LONG-TERM EFFECTS):

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* Stress exacerbates the cognitive deficits of Fmr1-KO mice at both ages

* Stress affected anxiety, locomotion, social interaction and communication in mice of both genotypes, especially at aging

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