A, Cell models were transfected with either 30 nM of nontargeting negative control siRNA or GPR173 targeting siRNA for 48 hours, and then GPR173 mRNA expression was measured by quantitative real-time PCR. GPR173 mRNA expression was reduced by 43% in the mHypoA-GnRH/GFP cell model (Ai) and by 37% in the mHypoA-Kiss/GFP-3 cell model (Aii) with the GPR173 siRNA. B, The mHypoA-GnRH/GFP cell model was treated with 10 nM PNX for 2 hours after a 48-hour transfection with either negative control nontargeting siRNA or GPR173 targeting siRNA. RNA was isolated and mRNA expressions of GnRH (Bi), GnRH-R (Bii) and C/EBP-β (Biii) were measured using quantitative real-time PCR. The mHypoA-Kiss/GFP cell model was treated with 100 nM PNX for 24 hours after a 48-hour transfection with either negative control nontargeting siRNA or GPR173 targeting siRNA. The RNA was isolated, and the mRNA expressions of Kiss1 (Ci) and C/EBP-β (Cii) were measured using quantitative real-time PCR. The mRNA levels were normalized to the housekeeping gene histone 3a. Results are expressed as mean ± SEM (n = 4–9 independent experiments). *, P < .05; **, P < .01; ***, P < .001; ****, P < .001. n.s., not significant. Statistical significance was determined by a two-way ANOVA with Bonferroni's post hoc test or a Student's t test.