Conventional ambient temperature housing impacts central oxytocin levels in mice

Neuroscience depends heavily on research done in mice (Mus musculus), yet the field has done little to address the chronic cold stress mice perpetually face during conventional "room temperature" housing (20°C-22°C). Contributions from other biomedical fields, such as immunology, oncology, and metabolic physiology, have shown that housing mice at room temperature substantially impacts broad and fundamental aspects of murine biology in ways that negatively affect the translational value of the research derived from these animals. Prairie voles (Microtus ochragaster) are an alternative small rodent model for neuroscience that are adapted for cold weather and better tolerate the ambient temperature of conventional housing. Here, we examined the effect of 3 days of housing at one of three ambient temperature conditions: 20°C, 25°C, or 30°C on oxytocin and vasopressin immunoreactivity within the paraventricular nucleus of the hypothalamus in both mice and voles. We found that increases in ambient temperature above 20°C led to a 32% reduction in oxytocin immunoreactivity in mice, while having no effect in voles. Vasopressin was unaffected in either species. Since oxytocin is a pleiotropic neuropeptide, responsible for regulating a number of homeostatic, emotional, and social circuits, this work calls into question whether findings from mice housed at 20°C can be reliably translated to humans living in thermoneutral conditions. This finding should spur further neuroscience research to reconcile how the assumptions of conventional housing have shaped murine neurobiology.