# Impact of short-term housing temperature alteration on metabolic parameters and adipose tissue in female mice

## TL;DR

Short-term cold exposure before and during pregnancy in mice causes lasting changes in fat tissue structure and proteins, but not in energy metabolism.

## Contribution

Shows that brief temperature changes around pregnancy can durably alter maternal adipose tissue.

## Key findings

- Cold-exposed mice had increased lean mass and reduced fat mass.
- Adipose tissue showed smaller fat cells and increased vascularity.
- 38 differentially expressed proteins were linked to mitochondrial and mTOR pathways.

## Abstract

Ambient temperature significantly influences physiological and metabolic processes in rodents, affecting obesity and related disorders. Mice housed below thermoneutral temperatures exhibit increased energy expenditure and sympathetic-driven brown fat activation, whereas thermoneutral housing (~30°C) reduces these responses. This study aimed to determine whether short-term exposure to altered housing temperatures before and during pregnancy induces lasting changes in maternal adipose tissue. We hypothesized that even brief exposure during this critical window could cause persistent structural and molecular alterations in adipose tissue.

Female C57BL/6J mice were housed at cold (CE, 8°C), thermoneutral (TN, 30°C), or standard room temperature (RT, 22°C) conditions for one week before and throughout pregnancy. All mice were returned to RT post-delivery. Phenotypic assessments—including glucose tolerance, energy expenditure, histology, and proteomics—were performed after lactation.

Temperature exposure did not significantly affect litter size or pup survival. CE-exposed mice showed increased total body weight driven by lean mass gains and reduced fat mass. Adipose tissue showed smaller adipocytes in iWAT and increased vascularity in BAT, though no persistent changes in thermogenic gene expression or glucose homeostasis were observed. Proteomic analysis of iWAT identified 38 differentially expressed proteins, with enrichment of pathways related to mitochondrial function and mTOR signaling.

Short-term cold exposure induced lasting histological and proteomic changes in iWAT and BAT without sustained effects on energy metabolism, likely due to reversion to RT and limited sample size.

Brief temperature manipulation around pregnancy can durably alter maternal adipose tissue architecture and molecular signatures, underscoring ambient temperature as an important modulator of maternal metabolic adaptation.