The effects of bilateral ovariectomy on uterine motility and levels of progesterone, oestradiol, cAMP, adrenaline and PGF2 alpha were studied in the rat at midpregnancy. Animals were randomly divided into two groups, at least 15 rats in each, sham-operated serving as controls and ovariectomized. The spontaneous uterine mechanical activity of Wistar rats was recorded isometrically and the electrical activities were recorded simultaneously by two bipolar electrodes. Within 30 minutes of ovariectomy a significant increase of the amplitude of uterine contractions was observed and the simultaneity of electrical activity was significantly improved; these effects became more pronounced at 1h post-ovariectomy (p less than 0.005). Plasma progesterone levels decreased by 20% (p less than 0.01) at 30 min and by 50% (p less than 0.001) 1h after ovariectomy, whereas oestrogen levels remained unchanged. Levels of adrenaline, cAMP and PGF2 alpha in the uterine tissue 1h following ovariectomy were affected as follows: adrenaline (p less than 0.05) and cAMP (p less than 0.001) were reduced and PGF2 alpha augmented (p less than 0.05). It appears that variation of the ratio oestrogens/progesterone induces precociously the activation of uterine mobility and exerts an effect on some factors involved in the regulation of the rat myometrium at midpregnancy.

Hexavalent chromium is a potent toxic agent. It has been found to be carcinogenic in human and animal. The purpose of the current work is to compare the effect of potassium dichromate (K₂Cr₂O₇) using variations in the dose, route of administration, and duration of exposure in male and female wistar albino rats with special focus on hematological parameters. K₂Cr₂O₇ was administered either in the drinking water with a dose of 30 mg/l for 20 consecutive days to male wistar albino rats, or as a single dose subcutaneously (s.c) at 10, 50 and 100 mg/Kg body weight (b w) to female wistar albino rats. Control groups received NaCl 0.9% (0.3 ml s.c), or drinking distilled water. Haematological parameters were recorded on day 3, 6, and 21 after subcutaneous exposure, or on day 10 and 20 after oral treatment. 10 mg/Kg b w of K₂Cr₂O₇ given subcutaneously induced during the first three days a marked decrease in the number of erythrocytes (-6%) of leucocytes (-30%) of platelets (-48%) and of hematocrit values (-15%), while the number of granulocytes is augmented (+124%) in comparison with control. Hemoglobin concentration and lymphocyte counts decreased markedly on day 6 after exposure. Chromium 50 mg/Kg b w, s.c mainly affected during the first three days the leucopoietic indices inducing leucopoenia (-55%), lymphopoenia
(-57%), monocytosis (+104%), granulocytosis (+204%), and thrombocytosis (+38%) if compared with control, while the erythrocytic counts and hemoglobin concentration decreased from day 6 (-22%) and (-21%) respectively until day 21 (-41%) and (-36%) respectively, and hematocrit values decreased at the end of experiment (-36%) in comparison with control. The higher dose of chromium (100 mg/Kg b w, s.c) reduced during the first three days the number of erythrocytes (-20%), platelets (-20%), total leucocytes (-55%), lymphocytes (-59%) and augmented the number of monocytes (+56 %), and granulocytes (+166%), while on day 6 the number of platelets augmented (+27%) in comparison with control. In drinking water, 30 mg/l of chromium given to male wistar albino rats had no effect on all erythropoietic parameters studied with the exception of the elevation (+21%) in platelet counts at the end of exposure, while the number of lymphocytes and total leucocytes were significantly reduced on day 20 after exposure (-37%) and (-37%) respectively. Conversely, the number of granulocytes and monocytes markedly increased on day 10 after exposure (+42%) and (+22%) respectively if compared with control. Short-term exposures to low dose of K₂Cr₂O_7, s.c induce in female wistar albino rats erythrocytopenia, thrombocytopenia, leucopoenia, lymphopaenia, granulocytosis, monocytosis, and a decrease in hematocrit values and hemoglobin concentration while in drinking water chromium was susceptible to affect in male rats the immune response inducing leucopoenia, lymphopoenia, monocytosis, and granulocytosis, while this oral route of exposure had no effect on erythropoietic parameters.

Several reports have suggested that soluble salts nickel may affect on hematopoiesis and development. In this study female Wistar albino rats (180-300g) received NiCl2, 6H2 O, subcutaneously (25, 50 and 100 mg/kg body weight (b w) or in drinking water (20 mg/100 ml). Selenium (0.3 mg/kg b w, s.c.) was combined to NiCl2 (100 mg/kg b w, s.c.). Control groups received NaCl 0.9% (0.3 ml s.c) or drinking distilled water. All groups of rats were injected on day 4 of pregnancy in pre-implantation period. Haematological parameters were recorded on day 6 and 21 of pregnancy. Developmental parameters were assessed on day 21 of pregnancy. 25 mg/kg b w, of NiCl2 s.c, induced on day 6 an immediate and significant decrease in erythrocyte counts, hematocrit values, and haemoglobin concentrations. This depletion was maintained on day 21 of pregnancy compared to control values.On other hand 50 mg/k b w, NiCl2, s.c, reduced on day 6 of pregnancy the erythrocyte counts, hematocrit values and platelets counts. Inversely, on day 21 this dose elevated the erythrocyte counts, hematocrit values and haemoglobin concentrations ,with depletion of the platelets counts compared to control values. In group introduced 100 mg/kg b w, of NiCl2, s.c had no effect on all haematological parameters studied. NiCl2, significantly reduced the maternal body weight on day 6 and 21 of pregnancy in a dose – dependent manner in rats treated subcutaneously and in drinking water compared with control values. NiCl2, s.c. (100 mg/kg b w) markedly reduced the number of live fetuses and elevated the number of abortions on day 21 of pregnancy compared to control values. NiCl2, s.c or in drinking water had no effect on fetal body weight. Selenium (0.3 mg/kg b w, s.c.) combined to NiCl2 (100 mg/kg b w, s.c.) did not improve the effect of NiCl2.

Objective: Potassium dichromate (K₂Cr₂O₇) is a potent pollutant for human and animal health. The purpose of the current work is to compare the effect of K₂Cr₂O₇ using variations in the dose, route of administration and duration of exposure in male and female Wistar albino rats and to research the interaction of chromium and selenium with a special focus on hematopoiesis. 

Materials and methods: K₂Cr₂O₇ was subcutaneously administered alone (10, 50 and 100 mg/kg body weight) or K₂Cr₂O₇ (10 mg/kg) in association with selenium (0.3 mg/kg) was administered to female Wistar albino rats. Male rats received in their drinking water K₂Cr₂O₇ (30 mg/L/day) alone or in association with Se (0.3 mg/L/day) for 20 consecutive days. The hematological parameters were evaluated on days 3, 6 and 21 after subcutaneous (sc.) treatment in female rats and on days 10 and 20 after oral administration in male rats. 

Results: K₂Cr₂O₇₋ induced during the first three days a significant (p < 0.05) dose-dependent decrease in the number of erythrocytes, platelets, leucocytes, lymphocytes and the hematocrit levels, and a dose-dependent increase in the number of granulocytes and monocytes. In the drinking water, chromium sc. significantly decreased the number of leucocytes and lymphocytes on day 10 after treatment and elevated the number of granulocytes and monocytes 20 days later. Selenium sc. counterbalanced the hematotoxic effects of chromium in female rats. 

Conclusion: These results suggest that the selenium has a protective role against the hematotoxicity of subcutaneous chromium in female Wistar rats.

Nickel Is A Heavy Metal That May Affect The Function Of The Thyroid. The Present Study Was Undertaken To Assess The Protective Effects Of Selenium And Zinc Against Nickel-induced Thyrotoxicity In Preimplanted Wistar Albino Rats. Nickel Is Administered Alone (100 Mg/kg Body Weight) Subcutaneously Or In Combination With Selenium (0.3 Mg/kg Body Weight) Either With Zinc (20 Mg/kg Body Weight) Or Combined With Both Selenium And Zinc. All Groups Of Rats Were Injected On Day 3 Of Gestation In The Pre-implantation Period. Exposure Of Rats To Nickel Caused A Significant Decrease In Maternal Body Weight On Days 6 And 20 Of Gestation And An Increase In Absolute And Relative Thyroid Weight Compared To The Controls. Nickel Treatment Was Also Led In Decreased Plasma Triiodothyronine, Thyroxine With A Concomitant Significant Increase In Thyroid-stimulating Hormone Levels When Compared To Control. These Changes Were Confirmed By Histological Damages. However, Co-administration Of Selenium And/or Zinc To Nickel-treated Rats Restored The Hormonal And Histological Aspects. Our Findings Suggested That Selenium And Zinc Ameliorated Nickel Induced Thyroid Damage.