Theffects' in vivo of acetorphan, an _enkephalinase inhibitor and naloxone, an opiate antagonist on the - - oxytocin- induced myometrial mechanical activity were studied at day 21 of pregnancy in rats. Acetarpban" I 10 mg kg -1 (i.v.) increased (344%) spontaneous uterine contractions duration only at 0-10 min period, but - did not modify amplitude. This increase in the duration was blocked by naloxone 5 mg ks -1, which had no effect on the amplitude or duration of contractions when given alone. Oxytocin (~T), I, 10 and I 100 mIU (i.v.) stimulated in a dose dependent manner, spontaneous uterine contractions duration but did not alter the amplitude of contractions. Blocking the opioid peptides by naloxone, 5 mg kg -1 (s.c.) injected --10min before OT strongly potentiated the effect of the lowest dose of OT (1 mlU) b-yabout of 59&Ofn and doubled the amplitude of contractions during the 30 min observation period. When acetorphan, 10 mg kg _-1 (i.v.) administered 30 min before the lowest dose of OT studied, 1 mID (i.v.), It induced a slight increase by .about 88% in uterine contractions duration produced by OT alone, The amplitude remained unchanged. These -results suggested that uterine contractions induced by OT in late pregnancy in rats might be regulated by enkephalinergie and enkephalinasic systems

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.

Nickel chloride (NiCl₂) is a heavy metal that may affect the function of the thyroid. Selenium (Se) and zinc (Zn) are essential trace elements involved in thyroid hormone metabolism. However, little is reported about thyrotoxicity during gestation. The current study aimed to investigate the protective effects of selenium and zinc against NiCl₂-induced thyrotoxicity in pregnant Wistar rats. Female rats were treated subcutaneously (s.c.) on the 3rd day of pregnancy, with NaCl 0.9% and served as control, NiCl₂ (100 mg/kg body weight (BW)) alone, or in association with Se (0.3 mg/kg, s.c.), ZnCl₂ (20 mg/kg, s.c.), or both of them simultaneously. Oxidative stress parameters, thyroid biomarkers, and histopathological examination were evaluated. Results showed that NiCl₂ exposure caused a significant decrease in maternal body weight and an increase in absolute and relative thyroid weight compared to the controls. NiCl₂ administration also led to decreased plasma triiodothyronine (T3) and thyroxine (T4) with a concomitant significant increase in thyroid-stimulating hormone (TSH) levels when compared to that of control. In addition, an overall pro-oxidant effect was associated with a decrease in the reduced glutathione (GSH) and nonprotein thiol (NPSH) contents and the enzymatic activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD), and an increase in malondialdehyde (MDA). These biochemical disturbances were confirmed by histological changes. However, the co-treatment of Se and/or ZnCl₂ attenuates NiCl₂-induced changes. Our findings suggested that Se and ZnCl₂ ameliorated NiCl₂-induced thyrotoxicity in pregnant Wistar rats by exhibiting antioxidant effects.

Hexavalent chromium (CrVI) compounds are potent toxicants commonly used in numerous industries. Thus, potential toxic effects and health hazards are of high relevance. Selenium (Se) and zinc (Zn) are known for their antioxidant and chemoprotective properties. However, little is known about their protective effects against CrVI-induced renal damage during pregnancy. In this context, the present study aimed to investigate the protective efficacy of these two essential elements against potassium dichromate-induced nephrotoxicity in pregnant Wistar Albino rats. Female rats were divided into control and four treated groups of six each receiving subcutaneously on the 3rd day of pregnancy, K₂Cr₂O₇ (10 mg/kg, s.c. single dose) alone, or in association with Se (0.3 mg/kg, s.c. single dose), ZnCl₂ (20 mg/kg, s.c. single dose) or both of them simultaneously. The nephrotoxic effects were monitored by the evaluation of plasma renal parameters, oxidative stress biomarkers, DNA damage, and renal Cr content. The obtained results showed that K₂Cr₂O₇ disturbed renal biochemical markers, induced oxidative stress and DNA fragmentation in kidney tissues, and altered renal histoarchitecture. The co-administration of Se and/or ZnCl₂ has exhibited pronounced chelative, antioxidant, and genoprotective effects against K₂Cr₂O₇-induced renal damage and attenuated partially the histopathological alterations. These results suggest that Se and Zn can be used as efficient nephroprotective agents against K₂Cr₂O₇-induced toxicity in pregnant Wistar Albino rats.