Sex-related differences of urethane and sodium valproate effects on Ki-67 expression in urethane-induced lung tumors of mice.

The aim of the present study was to evaluate sex differences in tumorigenesis by assessing the number of Ki-67-positive cells [Ki-67(+)] in urethane-induced mice lung tumors and the effect of sodium valproate (NaVP) in BALB/c mice. Gonad-intact and gonadectomized female and male mice were divided into the following groups: i) Treated with urethane, ii) treated with urethane and NaVP and iii) gonad-intact or gonadectomized control. Urethane (total 50 mg/mouse) was injected intraperitoneally. The NaVP 0.4% solution was administered orally for 6 months. Histologically, lung tumors were divided into adenomas and adenocarcinomas and assessed immunohistochemically using antibodies against Ki-67. The Ki-67(+) was calculated per one mm2 of a tumor. In adenomas, Ki-67(+) in the urethane-treated gonad-intact males was significantly higher than in females (P=0.001) and in castrated males (P<0.01); Ki-67(+) in adenomas of the urethane-treated gonad-intact males was significantly higher than in urethane-NaVP-treated ones (P<0.04). No significant differences were found in analogous female groups. In adenocarcinomas, Ki-67(+) in urethane-treated gonad-intact males was significantly higher than in females and gonadectomized mice of both sexes (P<0.001), and in ovariectomized females was significantly higher than in ovary-intact group (P=0.01). A significantly higher number of Ki-67(+) cells were observed in gonad-intact adenocarcinomas of the urethane-NaVP-treated females compared with the urethane-treated ones (P<0.001). Comparing between urethane-NaVP-treated gonadectomized males and females in adenocarcinomas, determined that Ki-67(+) was significantly lower in females (P=0.005). In adenocarcinomas, Ki-67(+) in urethane-NaVP-treated gonadectomized males and females was significantly lower than in gonad-intact mice of the same sex (P<0.001). In summary, gonadectomy with NaVP treatment decreased Ki-67(+) in adenocarcinomas for mice of both sexes. The results of the present study indicate sex-related differences in mice lung tumorigenesis, and a sex-related effect of NaVP on progression in urethane-induced BALB/c mice lung tumors.

Sodium Valproate Enhances the Urethane-Induced Lung Adenomas and Suppresses Malignization of Adenomas in Ovariectomized Female Mice.

In the present study, the possible effect of sodium valproate (NaVP) on urethane-induced lung tumors in female mice has been evaluated. BALB/c mice (n = 60; 4-6 weeks old, females) were used in the following groups: (1) urethane-treated; (2) urethane-NaVP-treated; (3) only NaVP-treated; (4) control. In the same groups, ovariectomized female mice (n = 60) were investigated. Urethane was given intraperitoneally, with a total dose of 50 mg/mouse. In NaVP-treated mice groups, 0.4% aqueous solution of NaVP was offered to mice ad libitum. The duration of the experiment was 6 months. The number of tumors per mouse in ovariectomized mice and in those treated with urethane and NaVP was significantly higher than in mice treated with urethane only (8.29 ± 0.58 versus 6.0 ± 0.63, p < 0.02). No significant difference in the number of tumors per mouse was revealed while comparing the nonovariectomized urethane- and urethane-NaVP-treated groups (p = 0.13). A significant decrease of adenocarcinoma number in ovariectomized mice treated with a urethane-NaVP as compared with ovariectomized mice treated with urethane only was found (p = 0.031). NaVP together with low estrogen may have a protective effect on the malignization of adenomas in ovariectomized mice.

Sodium valproate effect on the structure of rat glandule thymus: Gender-related differences.

Sodium valproate (VPA) was shown to inhibit cell growth mechanisms such as cell cycle arrest, proliferation suppression, increase of apoptosis. Many aspects of the contribution of the VPA pharmacological mechanisms and their significance in gender-related processes have not been investigated. In our study, we have tested hypothesis that the influence of VPA on thymus weight and structure might be gender-related. The thymus of Wistar rats of both genders aged 8 weeks was investigated in the following groups (n = 6 each): controls, treated with VPA, castrated male and female treated with VPA, and the castrated control of both genders. The thymus weight, structural changes and area of cortical and medullar parts of the gland in slides stained with hematoxylin and eosin and immunohistochemically were assessed. A comparison of thymus weight of castrated male and of castrated VPA-treated male rats showed a significant thymus weight loss after VPA treatment (0.66 ± 0.04 g vs. 0.43 ± 0.03 g, p < 0.05). The treatment with VPA caused an about 6-fold (0.39 ± 0.12 vs. 0.07 ± 0.03) increase of Hassall's corpuscles (HCs) numbers per 1mm(2) in male and more than 4-fold increase (0.46 ± 0.07 vs. 0.10 ± 0.04) in female rats. In castrated males and females, the HCs number was also increased, but this increase was statistically significant only in male animals vs. controls (0.46 ± 0.10 vs. 0.07 ± 0.03, p < 0.001 in males; 0.29 ± 0.13 vs. 0.10 ± 0.04, p > 0.05 in females). When castrated male and female rats were treated with VPA, further increase of HC numbers was found. In our study, VPA has inhibited the proliferative capacity of thymocytes by diminishing the thymus weight and inducing a differentiation of thymic medullar epithelial cells into HCs. The diminishing of the gl. thymus weight under the influence of VPA was significant in castrated male rats. The number of HCs increased in animals of both genders under the influence of VPA. Gender differences in HCs development were noted in castrated animals.

Sodium valproate enhances urethane tumorigenicity in lungs of male but not female mice.

In the study, the possible effect of sodium valproate (NaVP) on urethane-induced lung tumors in mice has been evaluated. BALB/c mice (n = 120; 4-6 weeks old, both sexes) were used in the following groups: 1) urethane-treated, 2) urethane-NaVP-treated, 3) only NaVP-treated, 4) control. In the same groups, castrated male mice (n = 48) were investigated. Urethane was given by intraperitoneal injections 10 mg/mouse, twice a week, the total dose 50 mg/mouse. In NaVP-treated mice, the 0.4 % NaVP aqueous solution was offered to mice ad libitum. The duration of the experiment was 6 months. The number of tumors per mouse in urethane-NaVP-treated males was significantly higher than in those treated with urethane only (13.82 ± 1.12 vs 6.77 ± 0.43, p < 0.0001). No significant difference in the number of tumors per mouse was revealed while comparing the female urethane- and urethane-NaVP-treated groups (6.50 ± 0.79 vs 8.15 ± 0.55, p = 0.105). No difference in the number of tumors per mouse was found in urethane-NaVP-treated castrated males as compared with urethane-treated castrated males. However, in the urethane-NaVP-treated castrated males the number of tumors per mouse was significantly lower than in analogous non-castrated males (7.8 ± 1.67 vs 13.82 ± 1.12, p < 0.01). NaVP combined with urethane potentiates urethane tumorigenicity in BALB/c non-castrated but not in female and castrated male mice. These data indicate an important role of testosterone in the urethane-NaVP induced lung tumorigenesis.