Prolactin is known to have a wide range of functions during reproduction, from supporting lactation to initiating maternal behaviours. New research now indicates that prolactin also has a role in regulating body temperature during pregnancy in mice.

The study involved mice with adenovirus-Cre deletion of the gene that encodes prolactin receptor (Prlr) in the preoptic area and mice with conditional deletion of Prlr in glutamatergic neurons. Telemetry measurement of body temperature was used to assess changes over the course of pregnancy. “The most significant finding was that prolactin action on glutamatergic neurons in the preoptic area is required to defend body temperature when faced with thermal challenge during pregnancy,” explains Brown. At the standard rodent housing temperature (22 °C), mice that lacked Prlr in glutamatergic neurons had no changes in body temperature or litter survival compared with wild-type mice. However, a thermal challenge (housing at 30 °C) led to hyperthermia during pregnancy in the mice that lacked Prlr, and to loss of litters after parturition.