Evaluation of male-mediated reproductive toxic effects of methamidophos in the mouse.

The reproductive toxicity of the insecticide methamidophos was studied in male mice. Adult male mice were treated by gavage with methamidophos at doses of 0, 1, 2 and 3 mg kg(-1) day(-1) for 4 weeks before mating with untreated females. Brain and skeletal muscle acetylcholinesterase activity was inhibited in the middle- and high-treated groups. Methamidophos treatment was associated with a decreased number of live foetuses and an increased number of dead and resorption foetuses at 2 and 3 mg kg(-1) day(-1) treated groups. The per cent morphologically normal spermatozoa were affected in the 2 and 3 mg kg(-1) day(-1) dose groups; however, sperm motility and count were decreased in the same treated groups compared to the control. Histological examination of brain, muscles, testes and epididymis revealed histological abnormalities in a dose-dependent manner. The current study demonstrated adverse effects of male methamidophos exposure on pregnancy outcome with effects on sperm parameters at 2 and 3 mg kg(-1) day(-1) .

Reproductive toxicology of acephate in male mice.

The reproductive toxicity of the insecticide acephate was studied in male mice. Adult male mice were treated by gavage with acephate at doses of 0, 7, 14, and 28 mg/kg/day for 4 weeks before mating with untreated females. Signs of cholinergic effects were observed in the 28 mg/kg/day group. Brain and skeletal muscle acetylcholinesterase activity was inhibited only in this group. Acephate treatment was associated with a decreased number of implantations and live fetuses, and an increased number of early resorptions at 28 mg/kg/day. The percent morphologically normal spermatozoa was unaffected in all dose groups; however, sperm motility and count were decreased in the 14 and 28 mg/kg/day groups compared to the control. Histologic examination of brain did not reveal any abnormalities. Dose related histologic changes, including degeneration of muscle fibers, were observed in the muscles of male mice treated with any of the doses of acephate. The current study demonstrated adverse effects of male acephate exposure on pregnancy outcome with effects on sperm parameters at 14 and 28 mg/kg/day.

Developmental toxicity of acephate by gavage in mice.

Acephate (O,S - dimethyl acetyl phosphoramidothioate), an organophosphate insecticide, was evaluated for its potential to produce developmental toxicity in mice after oral administration. Pregnant ICR (CD-1) mice were given sublethal doses of 0 (distilled water), 7, 14, and 28 mg/kg/day acephate by gavage on Gestation Days 6 through 15. Maternal effects in the 28 mg/kg/day dose group included cholinergic signs, decreased body weight at 15 and 18 days of gestation, and decreased absolute and relative brain weight. Placental weight was also decreased and liver weight was increased in the high dose group. Absolute and relative brain weight was decreased in the 14 mg/kg/day group. No maternal effects were apparent in the 7 mg/kg/day dose group. Maternal exposure to acephate during organogenesis significantly affected the number of implantations, number of live fetuses, number of early resorptions, mean fetal weight, and the incidence of external and skeletal malformations in the 28 mg/kg/day dose group. No visceral malformations were observed. On the basis of the present results acephate showed maternal and developmental toxicity at 28 mg/kg/day.