Acute and subacute metabolic and endocrine effects of clenbuterol in female pigs.

The aim of the study was to assess the relationship between acute and subacute metabolic and endocrine effects after intravenous administration of the beta2-adrenergic agonist clenbuterol in a growth-promoting dose to female pigs. Acute metabolic and endocrine effects were assessed by measuring the blood glucose, serum insulin and nonesterified fatty acid (NEFA) concentrations during 300 min after a single administration of clenbuterol. Significantly higher serum insulin and NEFA concentrations (19.90 +/- 2.50 microU/ml, p<0.01, and 0.69 +/- 0.04 mmol/L, p<0.001, respectively) were measured 30 min after the preprandial administration of clenbuterol in female pigs. Over the same period, the levels of blood glucose (4.42 +/- 0.30 mmol/L) showed no difference from those of control pigs. The postprandial serum NEFA concentration decreased moderately during 210 min after feeding. Postprandial blood glucose and insulin concentrations increased and reached maximal levels 120 min after clenbuterol administration (10.91 +/- 0.60 mmol/L and 85.22 +/- 7.24 microU/ml, respectively), and returned to basal levels at 300 min (4.20 +/- 0.21 mmol/L and 7.75 +/- 1.60 microU/ml, respectively) after the administration of clenbuterol. Subacute metabolic and endocrine effects were assessed by measuring the blood glucose, serum insulin and NEFA concentrations for 21 days after the repeated doses of clenbuterol. In addition, the influence of clenbuterol administration on the endocrine regulation of the onset of the next expected oestrus in female pigs was assessed by measuring their serum 17beta-oestradiol and progesterone concentrations. Blood glucose, serum insulin and NEFA concentrations after the last administration of clenbuterol did not differ significantly from those in control animals. The onset of the next expected oestrus occurred regularly without any significant difference in serum 17beta-oestradiol or progesterone concentrations between the treated (9.83 +/- 2.60 pg/ml and 0.15 +/- 0.03 ng/ml) and control pigs (8.52 +/- 2.70 pg/ml and 0.25 +/- 0.06 ng/ml). The study results suggest the duration of intravenous administration of clenbuterol in a growth-promoting dose necessary to influence the metabolic and endocrine activities in female pigs.

Reproductive disturbance caused by an S-triazine herbicide in pigs.

The aim of the study was to assess the effect of subacute treatment with a low dose of atrazine (1,3,5-triazine-2,4-diamine, 6-chloro-N-ethyl-N'-(1-methyl-ethyl), an s-triazine herbicide, on endocrine oestrus regulation in gilts. A group of nine gilts (F1 generation of Swedish Landrace x Large Yorkshire) were treated with 1 mg atrazine/kg body mass daily, mixed to the feed for 19 days before the onset of expected oestrus. Blood samples were obtained by cranial vena cava puncture three times daily at 3-h intervals on five post-treatment days, i.e. before and during oestrus. The serum concentration of oestradiol-17 beta (E2) was determined by the fluoroimmunochemical method. On Day -2 before the onset of expected oestrus, a significantly lower (P < 0.001) E2 concentration was measured in the serum of treated gilts (31.25 +/- 1.95 and 39.32 +/- 1.38 pg/mL) than in the control pigs (51.43 +/- 1.29 and 68.59 +/- 2.99 pg/mL). In contrast, the E2 concentration measured in the serum of treated animals was significantly higher (P < 0.001) on the day of the expected onset of oestrus and on the subsequent two days (35.43 +/- 1.85, 53.92 +/- 1.98 and 60.32 +/- 2.35 pg/mL, respectively) than in the control animals (13.52 +/- 1.79, 21.53 +/- 1.35 and 20.05 +/- 1.46 pg/mL, respectively). Insufficient serum E2 concentration of the treated gilts resulted in a failure of expected oestrus, as indicated also by the state of dioestrus demonstrated by histopathological examination of the uterus.

Serum biochemical changes associated with cystic ovarian degeneration in pigs after atrazine treatment.

Biochemical and histopathological parameters of the ovarian function were observed to assess the toxic effect of low dose of atrazine, an s-triazine herbicide, in female pigs (gilts) undergoing intensive breeding. Female pigs (cross-bred between Swedish and German landrace) received 2 mg atrazine kg-1 body wt. in feed daily during 19 days of the oestrous cycle. The last treatment day corresponded to day -3 of the onset of the next expected oestrus. Blood samples were collected 3 times daily at 3-h intervals on the first 5 post-treatment days. Serum 17 beta-oestradiol (17 beta-E) and progesterone (P) concentrations were determined. A significantly higher (P < 0.05 and P < 0.001, respectively) serum 17 beta-E concentration was recorded 48 and 24 h before the onset of the next expected oestrus in atrazine-treated pigs, as compared to intact pigs. The onset of the next expected oestrus failed to occur, but no other adverse clinical reactions associated with the treatment were recorded. Histopathological examination of the ovaries of treated pigs indicated multiple ovarian follicular cysts and persistence of corpus luteum. Biochemical and histopathological findings showed that subacute exposure of female pigs to low dose of atrazine prolonged their oestrous cycle.

Seasonal atrazine contamination of drinking water in pig-breeding farm surroundings in agricultural and industrial areas of Croatia.

Atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) a s-triazine herbicide, has been widely used in Croatian agriculture. Due to atrazine extensive use and its biodegradation in nature within at least one year (Klassen and Kodoum 1979), atrazine residues are found in ground, surface, drain and drinking water (Vidacek et al. 1994; Gojmerac et al. 1994). Groundwater downgradient from atrazine treated fields may show seasonal concentration peaks which could exceed the safe level (Wehtje et al. 1983). Therefore, the use of atrazine includes permanent control of its residues in water, particularly in relation to its use as a herbicidal chemical and groundwater contamination (Graham 1991). Furthermore, the presence of atrazine in the environment and its possible ingestion via the water, food and feed chain, may present a risk for the animal and human health. The analysis of atrazine residues in soil can be performed by either colorimetry or high performance liquid chromatography (HPLC) (Vickrey et al. 1980), and in water, soil and food by immunoassay in comparison with HPLC or gas chromatography/mass spectrometry (GS-MS) (Bushway et al. 1988; Bushway et al. 1989; Bushway et al. 1992; Thurman et al. 1990). We describe the use of enzyme-linked immunosorbent assay (ELISA) for one-year seasonal monitoring of atrazine residues in drinking water from two differently situated pig-breeding farms (agricultural and industrial areas) in Croatia. Results obtained by ELISA were compared to those produced by HPLC.

Effect of s-triazine compounds on testosterone metabolism in the rat prostate.

The influence of s-triazine compounds (atrazine, prometryne and deethylatrazine) on testosterone conversion and 5 alpha-dihydrotestosterone-receptor complex formation was studied in vitro and in vivo in the rat prostate. A marked in vitro influence of atrazine and prometryne (from 0.465 to 1.392 mumol) and their mixtures (in total concentration, 0.928 mumol) on 5 alpha-dihydrotestosterone formation was detected. 5 alpha-Dihydrotestosterone-specific receptor complex formation was inhibited in vitro by ca. 0.5 mumol of atrazine or deethylatrazine and only in vivo by 6 mg of atrazine 100 g-1 body wt. daily during 7 days in the prostate cytosol. The inhibition of the enzymic activities responsible for testosterone conversion and steroid hormone-receptor complex formation was non-competitive and reversible, and s-triazine compounds act as antiandrogens.

Serum biochemical and histopathological changes related to the hepatic function in pigs following atrazine treatment.

Biochemical and histopathological parameters of the hepatic function were used to quantify the hepatotoxic effects of atrazine in female pigs (gilts) undergoing intensive breeding. Female pigs (cross-bred Swedish and German landrace) received 2 mg atrazine kg-1 body wt. in feed daily during 19 days of the oestrous cycle. The last treatment day corresponded to day -3 of the onset of the next expected oestrus. Blood samples were collected three times daily at 3-h intervals on the first four post-treatment days. Serum activities of gamma-glutamyltransferase (GGT), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (AP) were determined. Serum activity of GGT was significantly increased throughout the four post-treatment days. In comparison with the control values, a slight but not significant decrease was observed in the serum activities of ALT, AST and AP. Histopathological examination of the liver of exposed pigs showed mild centrolobular parenchymatous degeneration. Interstitial connective tissue proliferation resulted in narrow and irregular bile canaliculi.

Testosterone metabolism in neuroendocrine organs in male rats under atrazine and deethylatrazine influence.

The inhibitory influence of atrazine and deethylatrazine on testosterone metabolism in male rat anterior pituitary and hypothalamus were studied under in vivo and in vitro experimental conditions. In vivo strong influence of atrazine (12 mg/100 g by wt. daily during 7 days) on 5 alpha-R, 3 alpha- and 17 beta-HSD activities was detected in the anterior pituitary. This dose provokes a significant increase in the weight of the pituitary gland, with hyperemia and hypertrophy of chromophobic cells with vacuolar degeneration. In vivo treatment of male rats with the same dose of deethylatrazine markedly inhibited 5 alpha-R activity in the anterior pituitary. The rate of 5 alpha-R activity inhibition in the anterior pituitary was the same after in vivo treatment with atrazine (37.3%) as with deethylatrazine (33.9%). This could suggest that the mechanism of inhibition of deethylatrazine is similar to that of atrazine. In vitro atrazine or deethylatrazine addition into the incubation medium significantly (P less than 0.01) inhibited 5 alpha-R, 3 alpha- and 17 beta-HSD activities in the anterior pituitary. The inhibition of 5 alpha-R activity was marked more by atrazine than deethylatrazine, while 3 alpha- and 17 beta-HSD activities were inhibited at the same rate. In vivo treatment with the same dose of atrazine or deethylatrazine (12 mg/100 g by wt daily 7 days) significantly inhibited (P less than 0.01) 5 alpha-R and 17 beta-HSD at the male rat hypothalamic level. 3 alpha-HSD activity inhibition was not significant for either compound. The in vitro addition of deethylatrazine was much more effective (P less than 0.01) in inhibiting 5 alpha-R, 3 alpha- and 17 beta-HSD in male rat hypothalamus than atrazine. In spite of this, deethylatrazine seems to be less toxic in in vivo experiments due to its higher polarity and faster biodegradation.

Indirect influence of s-triazines on rat gonadotropic mechanism at early postnatal period.

Daily s.c. injections of atrazine and deethylatrazine to rat mothers during pregnancy only or during pregnancy and lactation influenced the pituitary-gonadal axis of male and female offsprings. In female and male offspring, slow maturation of gonadotropic system is evident and as a consequence modified male and female pituitary 5 alpha-R activity is present. The number of specific steroid-hormone receptor sites at the offsprings' gonads is unchanged if the mothers were treated only during pregnancy, but 5 alpha-DHT prostate receptors are strongly inhibited in offspring of mothers treated with atrazine and deethylatrazine during pregnancy and lactation.