Long-term repetitive exposure to excess iodine induces mitochondrial apoptosis, and alters monoamine neurotransmitters in hippocampus of rats of different genders.

The influence of excess iodine on human health has been paid more and more attention. Although numerous studies have reported that excess iodine may cause deleterious effects, the mental damage and its mechanism is yet to be identified. Using Sprague-Dawley rats exposed to excess iodine from pregnancy to 6 months post-delivery as in vivo model, this study explored the impacts of long-term repetitive excess iodine administration on the hippocampus of offspring rats, focusing on mitochondrial apoptosis pathway, with changes in monoamine neurotransmitters. The results showed that excess iodine could increase urinary iodine and brain organ coefficient in offspring of both genders, change the hippocampal cell structure, and damage the spatial learning and memory capacities. Poly ADP-ribose polymerase (PARP), P53, Cleaved Caspase-3, and cytochrome C proteins expression increased and Bcl2 protein expression decreased in hippocampus of excess iodine-treated offspring, indicating that excess iodine could activate the mitochondrial apoptosis pathway. Besides, excess iodine showed different effects on monoamine neurotransmitter in different gender. Collectively, our experimental data indicated that the learning and memory impairment induced by excess iodine may be mediated via mitochondrial apoptotic pathway. Long-term repetitive excess iodine exposure affected monoamine neurotransmitters in hippocampus of offspring rats.