Brunswig-Spickenheier B, Mukhopadhyay A K
Institute for Hormone and Fertility Research, University of Hamburg, Germany.
Biol Reprod. 1997 Oct;57(4):700-6. doi: 10.1095/biolreprod57.4.700.
Gonadal function is known to be controlled by many factors, including locally acting cytokines like tumor necrosis factor alpha (TNF alpha). One of the ways this cytokine acts is via the nitric oxide (NO)-cGMP pathway. Since we have shown that in the ovary theca cells are a target of TNF alpha's action, it was of interest to determine whether TNF alpha stimulates the NO-cGMP pathway in these cells and whether such a mechanism can be implicated in the observed TNF alpha-mediated inhibition of LH-stimulated prorenin synthesis and secretion. Treatment of isolated theca cells with TNF alpha resulted in a dose- and time-dependent increase in cGMP production. This increase was not detectable until 6 h after the addition of TNF alpha and was totally abolished by the protein synthesis inhibitor cycloheximide. Addition of either L-N6-nitroarginine methyl ester (L-NAME), an inhibitor of all three NO synthase (NOS) isoforms or 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT), a specific inhibitor of the inducible isoform of the enzyme, likewise reversed the action of TNF alpha on cGMP formation. Finally, addition of 1H-[1,2,4]oxadiazolo [4,3-a] quinoxalin 1-one (ODQ), an inhibitor of NO-sensitive soluble guanylate cyclase, resulted in a concentration-dependent reduction of TNF alpha-stimulated cGMP formation. In contrast, the TNF alpha-mediated inhibition of LH-stimulated prorenin secretion was not affected by either L-NAME, AMT, or ODQ. Also the addition of stimulators of soluble guanylate cyclase, sodium nitroprusside, and S-nitroso-N-acetylpenicillamine, or 8 bromo-cGMP had no effect on the action of LH on theca cells. We conclude that although TNF alpha is able to stimulate cGMP formation in theca cells by inducing the expression of inducible NOS, the mechanism underlying the TNF alpha-mediated inhibition of LH-stimulated prorenin production is independent of its ability to induce cGMP formation.
已知性腺功能受多种因素控制，包括局部作用的细胞因子，如肿瘤坏死因子α（TNFα）。这种细胞因子发挥作用的一种方式是通过一氧化氮（NO）-环鸟苷酸（cGMP）途径。由于我们已经表明，在卵巢中，卵泡膜细胞是TNFα作用的靶点，因此确定TNFα是否刺激这些细胞中的NO-cGMP途径，以及这种机制是否与观察到的TNFα介导的对促黄体生成素（LH）刺激的肾素原合成和分泌的抑制有关，就很有意义。用TNFα处理分离的卵泡膜细胞导致cGMP生成呈剂量和时间依赖性增加。直到添加TNFα后6小时才检测到这种增加，并且蛋白质合成抑制剂环己酰亚胺完全消除了这种增加。添加L-N6-硝基精氨酸甲酯（L-NAME），一种所有三种一氧化氮合酶（NOS）同工型的抑制剂，或2-氨基-5,6-二氢-6-甲基-4H-1,3-噻嗪（AMT），该酶诱导型同工型的特异性抑制剂，同样逆转了TNFα对cGMP形成的作用。最后，添加1H-[1,2,4]恶二唑并[4,3-a]喹喔啉-1-酮（ODQ），一种对NO敏感的可溶性鸟苷酸环化酶的抑制剂，导致TNFα刺激的cGMP形成呈浓度依赖性降低。相反，TNFα介导的对LH刺激的肾素原分泌的抑制不受L-NAME、AMT或ODQ的影响。同样，添加可溶性鸟苷酸环化酶的刺激剂硝普钠、S-亚硝基-N-乙酰青霉胺或8-溴-cGMP对LH对卵泡膜细胞的作用也没有影响。我们得出结论，尽管TNFα能够通过诱导诱导型NOS的表达来刺激卵泡膜细胞中cGMP的形成，但TNFα介导的对LH刺激的肾素原产生的抑制机制与其诱导cGMP形成的能力无关。
