Acute effects of tetraethyltiuram disulfide on serum levels of hypophyseal hormones in humans

Epidemiological study of endocrinological effects of carbon disulfide

One hundred seventeen viscose rayon workers exposed to carbon disulfide, and 66 workers who were not exposed to any toxic agent in the working environment, underwent an endocrinological examination that included determination of thyroxine, luteinizing hormone, follicle-stimulating hormone, prolactin, and testosterone in serum by radioimmunoassay methods. In the viscose rayon factory, the working conditions had not changed subsequent to 1932. Personal monitoring performed in 17 jobs showed that carbon disulfide exposures varied from 4 to 112 mg/m3. A carbon disulfide cumulative exposure index was calculated for each individual. Univariate analysis of the hormone levels versus exposure showed significantly lower levels of prolactin in the exposed versus nonexposed subjects (p = .01). After adjustment for age, alcohol, smoking, body mass index, and stress level, the carbon disulfide cumulative exposure index was not associated with any of the hormones. This discrepancy from previous studies may result from differences in exposure, in selection of the population, or in confounding biases.

The dithiocarbamate fungicide thiram disrupts the hormonal control of ovulation in the female rat

Thiram has been reported to inhibit dopamine-beta-hydroxylase (D beta H), thereby affecting norepinephrine (NE) synthesis. Because NE is a neurotransmitter that is known to play an important role in the hypothalamic regulation of pituitary function, the acute effects of the thiram on the hormonal control of ovulation in the rat were investigated. Ovariectomized, estrogen-primed female rats were given a single injection of thiram (0, 6, 12, 25, 50, and 100 mg/kg, i.p.) at 1100 h and serum LH was measured in serial bleeds. Thiram at 100 and 50 mg/kg completely blocked the LH surge in all rats tested, while 12 and 25 mg/kg blocked the surge in 40 and 75% of the treated animals, respectively. Six mg/kg had no effect. Ovulation was then assessed in intact, proestrous females in response to thiram administration (0, 12, 25, or 50 mg/kg) at 0900, 1100, 1300, or 1800 h. Ovulation was blocked by 25 and 50 mg/kg at 1300 h in all rats, but when injected at 1100 h only the 50 mg/kg dose was effective. No such blockade was found with 50 mg/kg injected at 0900 and 1800 h. To assess the influence of thiram on the LH surge in intact rats, additional females were dosed at 1300 h on the day of proestrus and blood collected over that same day. Thiram at 50 mg/kg blocked the LH surge in all rats, while 25 mg/kg blocked the surge in 60% of the females tested. No effect occurred with 12 mg/kg.(ABSTRACT TRUNCATED AT 250 WORDS)

The antifertility and antiadrenergic actions of thiocarbamate fungicides in laying hens

The effects of the thiocarbamate fungicides, thiram, ziram, ferbam, maneb, and zineb, on norepinephrine synthesis by laying hens were investigated. Inhibition experiments with dopamine beta-hydroxylase purified from chicken adrenals indicated that thiram, ziram, and ferbam are potent competitive inhibitors with the substrate the substrate ascorbate. Maneb and zineb were without effect at comparable concentrations. Experiments investigating the interaction of thiram, ziram, and ferbam with cupric ions suggested that these compounds probably inhibit the enzyme by complexing the fully oxidized copper at its active site. Maneb and zineb also complexed cupric ions in solution and thus their failure to inhibit is not due to their inability to complex copper. When tested in vivo, thiram, ziram, and ferbam at po doses of 2.5 mg/kg or greater significantly reduced the conversion of radioactive dopa, given systemically, to brain norepinephrine. Since they did not affect the uptake of radioactive dopa by the brain or its subsequent decarboxylation within the brain to yield dopamine, these three compounds inhibit cerebral dopamine beta-hydroxylase in vivo. In contrast maneb and zineb at a po dose of 20 mg/kg had no significant effect on brain norepinephrine synthesis. Previously published results (Weppelman et al., Biol. Reprod. 23, 40-46, 1980) demonstrated that thiram, ziram, and ferbam (but not maneb or zineb) have antifertility action in laying hens. The correlation between this action and inhibition of dopamine beta-hydroxylase suggests that the antifertility effects of thiram, ziram, and ferbam might result from their antiadrenergic action. The observation that all doses of thiram in the diet which caused significant antigonadal action when fed to laying hens for 1 week also significantly decreased central and peripheral stores of norepinephrine supports this conclusion.