Cold stress induced morphological microglial activation and increased IL-1β expression in astroglial cells in rat brain

The present study investigated the possible impact of cold stress on the immune functions of the brain. Wistar rats were exposed to 4 °C for 2 h prior to analysis of immunohistochemical analysis of OX-42 and IL-1β, which are markers of microglia and inflammation, respectively. Exposure to cold stress induced morphological microglial activation in as early as 30 min, and the activation lasted up to 2 h following the stress. In addition, increased IL-1β-immunoreactivity was detected in the hippocampus and hypothalamus. However, IL-1β was not co-localized with microglia, and was predominantly expressed in astroglia. The present study provides the first evidence that cold stress contributes to neuro-immunomodulation in the brain through microglial activation and expression of IL-1β in astroglia.