〔Abstract〕 To investigate the effects of prostaglandin E2 (PGE2) microinjection into the median preoptic nucleus (MnPO) on core body temperature in female mice, and to clarify its underlying mechanism. Methods Microinjection cannula were implanted into the MnPO of female mice using stereotaxic surgery. Subsequently, a multi-channel temperature acquisition system was used to simultaneously monitor rectal and brown adipose tissue (BAT) temperatures before and after intra-MnPO injections of different reagents. To investigate the thermoregulatory effects of the microinjection of PGE2 into the MnPO, 12 female C57BL/6 mice were randomly divided into a saline group (n=6) and a PGE2 group (n=6), which were injected with 0.1 μL saline and PGE2 (2.8 mmol/L), respectively. To determine whether E-series prostaglandin receptor (EP)1, EP3, and EP4 receptors mediate the thermoregulatory effects of PGE2, 15 female C57BL/6 mice were randomly divided into 3 groups (n=5 per group). Each group received sequential microinjections into the MnPO of 0.1 μL of PGE2 (2.8 mmol/L), followed by a mixture of the respective EP antagonist (ant) (20 mmol/L)and PGE2 (2.8 mmol/L). Results Compared with baseline level, the rectal temperature (P<0.01) and BAT temperature (P<0.001) of female mice both increased significantly after microinjection of PGE2 into the MnPO. Compared with the saline group, the increases in rectal temperature (P<0.001) and BAT temperature (P<0.000 1) were significantly greater in the PGE2 group of mice. Furthermore, following the injection of PGE2 into MnPO, the increase in BAT temperature was found to be significantly greater than that in rectal temperature in mice (P<0.001). Compared to the administration of PGE2 alone, co-injection of an EP3 ant + PGE2 into the MnPO of mice resulted in a significantly smaller increase in both rectal temperature (P<0.001) and BAT temperature (P<0.001). In contrast, the increases in rectal and BAT temperatures following MnPO injection of either EP1 ant + PGE2 or EP4 ant + PGE2 were not statistically significant (P>0.05 for both). Conclusion Injection of PGE2 into the MnPO elevates BAT and core body temperature in female mice via the EP3 receptor.