Effect of a gonadotropin releasing hormone analog on an experimental ovarian tumor: Direct and indirect actions
An ovary autotransplanted into the spleen of a bilaterally ovariectomized rat develops into a luteoma, which grows under constant gonadotropin hyperstimulation. The effect of a long-acting GnRH agonist (GnRH-a), on tumor growth and hormone secretion was investigated. Two experimental models were use...
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1995
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| Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00243205_v57_n3_p291_LuxLantos http://hdl.handle.net/20.500.12110/paper_00243205_v57_n3_p291_LuxLantos |
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| Sumario: | An ovary autotransplanted into the spleen of a bilaterally ovariectomized rat develops into a luteoma, which grows under constant gonadotropin hyperstimulation. The effect of a long-acting GnRH agonist (GnRH-a), on tumor growth and hormone secretion was investigated. Two experimental models were used: Model 1: GnRH-a (0.33 mg/rat sc) or estradiol valenanate (50 μg/rat sc injected once a week for four weeks) was administered simultaneously with ovary implantation; Model 2: the drugs were administered after 1 month of tumor development. The treatment with estradiol was used as a control of tumor regression. Saline injected ovarian grafted rats and Sham operated animals were used as controls. In Model 1: The GnRH-a significantly inhibited tumor development (Positive tumors: Saline: 100% vs GnRH-a: 43%, p < 0.01). In Model 2: the GnRH-a and estradiol significantly reduced the volume of one month old tumors (52% and 39% of initial volumes respectively, p < 0.01). Gonadotropin secretion was significantly inhibited or its increase blunted by the GnRH-a and by estradiol treatments in both models. Estradiol and progesterone in portal blood, which collects the steroids secreted by the luteoma, were significantly reduced by GnRH-a treatment in both models. On the other hand, in tumor cells cultured "in vitro", the GnRH-a was able to inhibit the LH induced progesterone secretion in a concentration dependent way. These results clearly show that the GnRH-a is effective in inhibiting tumor growth or reducing its volume, when already developed; furthermore, it suppresses tumor steroid hormone production. These actions were exerted at both the hypophyseal and tumor levels. © 1995. |
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