H_4受体介导组胺刺激AtT-20细胞分泌ACTH

H_4 receptor-mediated stimulation of histamine on AtT-20 cells to release ACTH

目的阐明介导小鼠垂体前叶瘤细胞株(AtT-20)分泌促肾上腺皮质激素(ACTH)的组胺(HA)受体亚型.方法体外培养AtT-20细胞,ELISA检测各HA受体亚型的激动剂和拮抗剂对AtT-20细胞分泌ACTH的影响;利用RT-PCR方法检测AtT-20细胞中H4受体mRNA的表达.结果①HA(10-8mol/L)作用于AtT-20细胞6h,ACTH分泌量(pmol/L)增加(5.7±1.1),与对照组相比(2.7±0.6)有显著差异(P<0.01);而组胺H1受体特异性拮抗剂扑尔敏(5.7±0.7)和H2受体特异性拮抗剂雷尼替丁(5.8±1.0)不能拮抗此效应.②HAH3和H4受体激动剂R-(α)-甲基组胺(10-7mol/L)同HA作用相似,能够促进AtT-20细胞分泌ACTH(5.9±1.3).③HAH4受体的特异拮抗剂JNJ777120(1-[(5-Chlo-ro-1H-indol-2-yl)carbonyl]-4-methylpiperazine)能够剂量依赖性拮抗HA促进AtT-20细胞释放ACTH的效应,当浓度为10-5mol/L时,HA的效应被完全阻断.④RT-PCR结果证实,在AtT-20细胞中存在组胺H4受体mRNA的内源性表达.结论HA调控AtT-20细胞分泌ACTH的作用由H4受体介导.

AIM： To clarify the subtype of histamine （HA） receptor which mediates Adrenocorticotropic Hormone （ACTH） release from mouse anterior pituitary tumor cell line ART-20. METHODS： ELISA assay was used to determine the effects of a variety of histamine receptor subtype-specific agonists and antagonists on ACTH release from AtT-20 cells. The expression of H4 receptor mRNA on AtT-20 cells was detected by RT-PCR and the PCR product was sequenced. RESULTS： ①HA （ 10^-8 mol/L） significantly accelerated the release of ACTH （pmol/L） from AtT- 20 cells （ 5.7 ± 1.1 vs 2.7 ± 0.6 in control, P 〈 0.01 ）. The histamine H1 -receptor specific antagonist Chlorpheniramine （5.7 ± 0. 7 ） and histamine H2-receptor specific antagonist Ranitidine （5.8 ± 1.0 ） did not inhibit the effect of HA. ② The same as HA, histamine H3-and H4-receptor agonist R-（ α ）-Methylhistamine （ 10 -7 mol/L） increased the release of ACTH from AtT-20 cells （5.9 ± 1.3 ）. ③ H4-receptor specific antagonist JNJ777120 （ 1-[ （ 5-Chloro-1H-indol-2-yl ） carbonyl ]- 4-methylpiperazine ） demonstrated a concentration-dependent inhibitory effect on the increasing ACTH secretion induced by HA, and the effect of HA was totally abolished by JNJ777120 at 10 ^-5 mol/L. ④ RT-PCR confirmed that AtT-20 cells presented an endogenous expression of H4-receptor mRNA. CONCLUSION： HA stimulates the release of ACTH from ART-20 cells through H4 receptor mediation.