Effects of intraperitoneally administered vitamin E and selenium on calcium oxalate renal stone formation: experimental study in rat.

Forty-eight Wistar rats were treated for 3 weeks with water containing 0.7% ethylene-glycol and divided into four groups. The first group, used as control, has received sodium chloride at 1 ml/100 g BW daily. The second group was intraperitoneally injected with selenium at 10 micrograms/d per 100 g BW as NaSeO3 for 3 weeks. The third group was intraperitoneally administered with 15 mg Vit E/d per 100 g BW as alpha-tocopherol acetate for 3 weeks. The last group was simultaneously administered vitamin E and Se at the same doses and periods as the precedent groups. One day before the end of the treatment, each animal was placed in a metabolic cage for collection of 24 h urine samples and determination of urinary creatinin, urea, calcium, magnesium, phosphate and oxalate levels. Immediately thereafter, all the rats were anesthetized and aortic blood was collected to determine the same parameters as in urine. The kidneys were also removed to determine calcium oxalate deposits, dry weight and to conduct a histological examination. Our results showed decreased ionic product and increased magnesium fractional reabsorption in the group receiving only selenium and in the group receiving selenium in combination with vitamin E, in comparison with the control animals. In view of the knowledge concerning the same protective action of Vit E and selenium, regardless of tubular membrane alteration, the absence of any inhibitory effect of Vit E on calcium oxalate formation suggests that selenium, like other minerals, could be stuck onto the crystal surface and would inhibit induction of new crystals, growth and aggregation.

Flavor avoidance learning and its implications in reducing strychnine baiting hazards to nontarget animals.

In reforested areas, underground strychnine baiting to control pocket gophers (Thomomys mazama) poses a hazard to golden mantled ground squirrels (Spermophilus lateralis) and yellow pine chipmunks (Eutamias amoenus). We designed this study to assess whether: 1) chemical insensitivity to bitter tastes might explain the ingestion of strychnine; 2) pocket gophers would avoid four bitter-tasting compounds: quebracho (QUEB), sucrose octaacetate (SOA), quinine hydrochloride (QHCl), and denatonium benzoate (DB); and 3) nontarget species could be trained to avoid strychnine paired with the most aversive compound. Our results showed that while all species readily consumed strychnine, the nontarget species could be conditioned to avoid it. Moreover, while high (0.1%) concentrations of DB, quinine hydrochloride, and quebracho reduced consumption by pocket gophers, 0.05% DB was inoffensive. Nontarget animals readily avoided 0.05% DB, and avoidance was stronger after conditioning. Together, our results suggest that all of the rodents tested are insensitive to strychnine, high concentrations of some bitter tastes may be effective pocket gopher repellents, and lower concentrations of DB may selectively repel nontarget animals from strychnine baits.

[Absence of litholytic effects of zinc sulfate and copper sulfate in experimental lithiasis in rats]. / Absence d'effets litholytiques du sulfate de zinc et du sulfate de cuivre vis-à-vis de la lithiase expérimentale chez le rat.

Seventy two male Wistar-strain rats were fed lithogenic diet with ethylene-glycol within three weeks. At the end of this treatment, six rats were killed in order to determine the oxalate and calcium concentrations in renal tissue. Remained rats was randomly divided in four series, each series consisting of three groups. In first series (T), the animals were treated with distilled water; in the second (D1Zn), the animals were treated intramuscularly with the zinc at the rate of 24 micrograms per 100 grams of body weight and per day; in the third (D2Zn), 240 micrograms of zinc were administrated to animals and in the last series (D2Cu), the animals were treated at the same dose as the previous series, but with the copper. The groups which making up each series were killed successively at the 5th, 10th and 15th day after ending treatment with ethyleneglycol in order to determine urinary pH, percentage of water in renal tissue, uremia and concentrations of oxalate and calcium in renal tissue. Then, the comparisons of means were carried out, at each time, between different treated groups and reference group which was treated with distilled water. Litholytic effect was found in all series, including that which had been treated with distilled water. However, compared to reference animals, no acceleration of litholytic process was induced by zinc or copper. The high doses used in these experimentations proved therefore that calcium oxalate calculi were insoluble by zinc and copper.

Role of testosterone in the sexual dimorphism of adrenal activity at puberty in the guinea-pig.

Sexual dimorphism in adrenal activity appeared during the pubertal period of the guinea-pig with plasma levels and binding of cortisol lower in male guinea-pigs compared with female, and metabolic clearance rate (MCR) of cortisol higher in male than in female animals. Gonadectomy of female guinea-pigs did not change the values of the parameters regulating adrenal activity. Castration of male guinea-pigs caused a rise in plasma cortisol levels by increasing the binding capacity of transcortin for cortisol and by decreasing cortisol MCR. Treatment of females with testosterone from day 24 produced a drop on day 50 in plasma cortisol levels following a decreased binding capacity of transcortin for cortisol and at the same time as cortisol MCR increased. Furthermore, the adrenal response to stress was higher in castrated than in control males and lower in testosterone-treated females compared with control females. Testosterone appeared to be the hormone responsible for sexual dimorphism in adrenal activity in the pubertal guinea-pig.

Changes in cortisol binding and metabolism during neonatal development in the guinea-pig.

The metabolic clearance rate and the binding of cortisol in plasma of male and female guinea-pigs were estimated at five stages between birth and weaning. The metabolic clearance rate for cortisol remained low in both sexes until day 10 post partum but increased to adult values by day 20. The level of free cortisol in plasma and the cortisol binding capacity of the plasma were higher at birth than on day 10 post partum; the values found on day 20 were similar to those of the adult guinea-pig. Surgical stress increased levels of cortisol in plasma on day 20 but not at birth.

Sexual dimorphism in binding and metabolism of cortisol during puberty in the guinea pig.

Sexual difference in plasma cortisol levels appeared in basal conditions on day 30 post-partum and values remained significantly higher in female guinea-pigs until day 70, disappearing on days 90 and 120. After stress, plasma cortisol levels increased in both sexes and the dimorphism was conserved with lower values obtained in males. Between days 30 and 70, cortisol metabolic clearance rate was significantly higher and binding capacity of transcortin for cortisol was significantly lower in males than in female guinea-pigs.