Figure 3.

GPR54 receptor antagonist peptide 234 inhibits the excitation of kisspeptin on POMC cells. A, A bar graph based on qPCR shows relative levels of GPR54 mRNA in several brain areas and in muscle (MUS), consistent with previous reports (Lee et al., 1999; Mikkelsen and Simonneaux, 2009). Four levels of the ARC were sampled, rostral to caudal (numbers show deciles in position from rostral to caudal, with 10 being in the rostralmost 10% of the arcuate nucleus, and 100 being in the caudalmost region of the nucleus). All regions of the arcuate nucleus expressed kisspeptin receptor mRNA. CER, Cerebellum; STR, striatum; HIP, hippocampus; MPO, medial preoptic area; MS, medial septum; MUs, muscle. The bars represent means; most bars are based on samples from four mice, each analyzed independently, with ARC10 and ARC95 based on three mice and muscle based on two mice. The flags are SEM. CT for MS was 29.4 for GRP54 and 21.7 for actin. B, A trace showing the firing of a POMC cell in the presence of peptide 234 (1 μm) and kisspeptin (Kiss) (100 nm). Initial membrane potential is shown under the trace. C, Bar graph showing the change in spike frequency after applying peptide 234 (1 μm) alone, kisspeptin (Kiss) (100 nm) with peptide 234 (1 μm), kisspeptin washout (Kiss W/O), and ACSF washout. D, Bar graph comparing the increase of spike frequency by kisspeptin (100 nm) with and without the pretreatment of peptide 234 (1 μm). E, Bar graph comparing the depolarization induced by kisspeptin (100 nm) with and without the pretreatment of peptide 234 (1 μm). **p < 0.01; n = 6; paired t test. ^#p < 0.05; ^##p < 0.01; group t test.