Abstract:

Objective: To observe the toxic effects of zinc threoninate chelate (Thr-Zn) and zinc sulfate on the embryo-fetal
development in Sprague-Dawley (SD) rats on days 6 to 15 of pregnancy when they were diluted with corn oil. Methods: The
pregnant rats were administered daily with Thr-Zn at a dose of 1 200 mg/(kg·d) bw or the same zinc dose from zinc sulfate
(575 mg/(kg·d)) by gavage during days 6 to 15 of pregnancy and the basic living conditions were observed. Body weights
were measured on days 0, 4, 8, 12, 16 and 20 of pregnancy, respectively. On day 20, the pregnant rats were sacrificed and
their uterus were collected and weighed. The numbers of corpora lutea, implantations, absorbed fetuses, dead fetuses and
live fetuses were examined. Fifty percent of fetuses were examined for visceral alterations and the remaining half were
examined for skeletal abnormalities. Results: For both the Thr-Zn and zinc sulfate groups on the 7th day, the food intake
was significantly decreased (P ＜ 0.05), and the weight gain also was significantly reduced (P ＜ 0.05). The Thr-Zn group
had 18 cases of sternal missing and compared with the corn oil group, the difference was statistically significant (P ＜ 0.05).
The zinc sulfate group had 13 cases of sternal missing and two pregnant rats died; compared with the corn oil group, the
difference was similarly statistically significant (P ＜ 0.05). Conclusions: High-dose administration of the two zinc sources
has certain reproductive toxicity on pregnant SD rats, but Thr-Zn is relatively safe.

Key words: zinc threoninate chelate, zinc sulfate, skeletal malformations, developmental toxicity