[Effects of lipopolysaccharide and dexamethasone on the expression of Kisspeptin/GPR54 in mouse hypothalamus].

OBJECTIVE: To evaluate the effects of lipopolysaccharide (LPS) and dexamethasone on function of hypothalamus-pituitary-testis axis and to explore the possible underlying mechanisms. METHODS: LPS (100 μg/kg), dexamethasone (DEX, 1 mg/kg) and phosphate buffer saline (PBS) were injected subcutaneously into castrated mice (n=5 in each group) for 4 weeks. The expression of Kisspeptin and its receptor GPR54 in hypothalamus were measured by immunohistochemistry, and plasma luteinizing hormone (LH) were measured by chemiluminescence immunoassay. RESULTS: After LPS and DEX were administered for 4 weeks, the LH level in LPS group and DEX group was (1.79±0.74) U/L and (2.19±0.60) U/L, respectively, which were lower than PBS group (4.87±1.25) U/L (all P<0.01). In LPS group, after treatment, the kisspeptin immunohistochemistry index in hypothalamus was 4.2±1.1, which was lower than the control group (10.2±1.6, P<0.05). The GPR54 immunohistochemistry index in hypothalamus was 3.6±0.5, which was lower than PBS group (6.2±1.8, P<0.05). In DEX group, the expressions of kisspeptin and GPR 54 in hypothalamus did not change after treatment. CONCLUSIONS: LPS may downregulate function of hypothalamus-pituitary-testis axis through Kisspeptin/GPR54 system. Dexamethasone could suppress function of gonadal axis as well, while the underlying mechanism is still unclear.