Teratogenicity in the rat of the venom from the scorpion Androctonus amoreuxi (Aud. & Sav.).

A. amoreuxi venom caused a high foetal resorption rate in rats, particularly when injected on days 9-11 of gestation. Vertebral and ossification defects and foetal weight loss were observed in many of the viable foetuses obtained from mothers treated with scorpion venom. Treatment of the rats with phentolamine in addition to the venom significantly reduced the venom-induced hyperglycemia. It also conferred some protection against foetal resorption but had only a slight effect on chondrification or foetal weight loss. This shows that hyperglycemia might be responsible for foetal mortality, but alone is not a decisive factor in the effect of the venom on the chondrification process. Treatment of the rats with triamterene reduced the foetal resorption rate and significantly decreased the effects of the venom on chondrification. However, marked stippling was observed in the long bones and was ascribed to marked mobilization of ionized calcium in the foetus. Foetuses removed from rats treated with phentolamine or triamterene in addition to the venom, however, showed flattened and depressed skulls, possibly from a missing 1st cervical vertebra or failure of the occipital fontanel to close. Treatment of the rats with the scorpion venom over a longer period of time and starting at an earlier time of gestation (days 7-14) caused total foetal resorption, which may be due to inhibition of histamine formation by the venom. The teratogenic effect of the venom appears to be the result of its metabolic effect and action on body electrolytes of the maternal animal, rather than to a direct effect on the foetuses. This was evidenced from experiments with labelled venom, where only a small fraction (0.08-0.33%) was detected in foetuses or placenta.