GPR120 is a long-chain fatty acid (LCFA) receptor that is specifically expressed in gonadotropes in the anterior pituitary gland in mice. The aim of this study was to investigate whether GPR120 is activated by free fatty acids in the pituitary of mice and mouse immortalized gonadotrope LβT2 cells. First, the effects of palmitate on GPR120, gonadotropic hormone b-subunits, and GnRH-receptor expression in gonadotropes were investigated in vitro. We observed palmitate-induced an increase in Gpr120 mRNA expression and a decrease in follicle-stimulating hormone b-subunit (Fshb) expression in LβT2 cells. Furthermore, palmitate exposure caused the phosphorylation of ERK1/2 in LβT2 cells, but no significant changes were observed in the expression levels of luteinizing hormone b-subunit (Lhb) and gonadotropin releasing hormone-receptor (Gnrh-r) mRNA and number of GPR120 immunoreactive cells. Next, diurnal variation in Gpr120 mRNA expression in the male mouse pituitary gland was investigated using ad libitum and night-time restricted feeding (active phase from 1900 to 0700 h) treatments. In ad libitum feeding group mice, Gpr120 mRNA expression at 1700 h was transiently higher than that measured at other times, and the peak blood non-esterified fatty acid (NEFA) levels were observed from 1300 to 1500 h. These results were not observed in night-time-restricted feeding group mice. These results suggest that GPR120 is activated by LCFAs to regulate follicle stimulating hormone (FSH) synthesis in the mouse gonadotropes.

中文翻译：

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小鼠脑垂体促性腺激素中Gpr120 mRNA 的表达受游离脂肪酸的调节

GPR120 是一种长链脂肪酸 (LCFA) 受体，在小鼠垂体前叶的促性腺激素中特异性表达。本研究的目的是研究 GPR120 是否被小鼠垂体和小鼠永生化促性腺激素 LβT2 细胞中的游离脂肪酸激活。首先，体外研究了棕榈酸酯对 GPR120、促性腺激素 b 亚基和促性腺激素中 GnRH 受体表达的影响。我们观察到棕榈酸诱导 LβT2 细胞中 Gpr120 mRNA 表达的增加和促卵泡激素 b 亚基 (Fshb) 表达的减少。此外，棕榈酸酯暴露导致 LβT2 细胞中 ERK1/2 的磷酸化，但黄体生成素b亚基（Lhb）和促性腺激素释放激素受体（Gnrh-r）mRNA的表达水平和GPR120免疫反应细胞的数量未见明显变化。接下来，使用随意和夜间限制进食（从 1900 到 0700 小时的活动期）处理研究雄性小鼠脑垂体中 Gpr120 mRNA 表达的昼夜变化。在随意喂养组小鼠中，Gpr120 mRNA 在 1700 h 的表达比其他时间测量的要高，并且在 1300 至 1500 h 观察到峰值血液非酯化脂肪酸 (NEFA) 水平。在夜间限制进食组小鼠中未观察到这些结果。这些结果表明 GPR120 被 LCFA 激活以调节小鼠促性腺激素中的促卵泡激素 (FSH) 合成。