Maternal LiCl exposure disrupts thyroid-cerebral axis in neonatal albino rats

Lithium and endocrine disruption: A concern for human health?

Lithium is a key medication for the treatment of psychiatric disorders and is also used in various industrial applications (including battery production and recycling). Here, we review published data on the endocrine-disrupting potential of lithium, with a particular focus on the thyroid hormone system. To this end, we used PubMed and Scopus databases to search for, select and review primary research addressing human and animal health endpoints during or after lithium exposure at non-teratogenic doses. Given the key role of thyroid hormones in neurodevelopmental processes, we focused at studies of the neural effects of developmental exposure to lithium in humans and animals. Our results show that lithium meets the World Health Organization's definition of a thyroid hormone system disruptor - particularly when used at therapeutic doses. When combined with knowledge of adverse outcome pathways linking molecular initiating events targeting thyroid function and neurodevelopmental outcomes, the neurodevelopmental data reported in animal experiments prompt us to suggest that lithium influences neurodevelopment. However, we cannot rule out the involvement of additional modes of action (i.e. unrelated to the thyroid hormone system) in the described neural effects. Given the increasing use of lithium salts in new technologies, attention must be paid to this emerging pollutant - particularly with regard to its potential effects at environmental doses on the thyroid hormone system and potential consequences on the developing nervous system.

Experimental data on lithium salts: From neuroprotection to multi-organ complications

Lithium-salts stand on the first line of therapy for the management of specific psychiatric conditions, mainly bipolar mood disorder. It is also known to protect the brain against neurodegenerative processes such as Alzheimer's disease. Despite the mentioned merits, recent studies have revealed that high dose or prolonged lithium intake deteriorate the function of multiple key organs including heart, ovaries, thyroid gland and kidneys. Mechanistically, both positive and negative effects of lithium are mediated through methylation of β-catenin nuclear-binding proteins which is potentiated by lithium-induced inhibition of GSK-3 or inositol monophosphatase. The current study briefly reviews the recent experimental data on lithium therapy considering both positive (i.e., neuroprotective) and negative aspects. In this regard, the question is that whether doses of lithium administered in experimental research are comparable with the therapeutic doses, as currently prescribed in clinical practice. It should be noted that the experimental data on animal studies, as widely reviewed here, could not be directly generalized to clinic. This is mainly because lithium doses applied in animal models are usually higher than therapeutic doses, however, there are evidence indicating that even animal to human translated doses of lithium, cause serious complications and this has been reported by meta-analyses on human studies. Therefore, we suggest the clinicians to use lithium-salts with precaution particularly in pregnancy and precisely adjust lithium concentration considering the patient's general health status to avoid lithium toxicity. Indeed, alternative approaches are recommended when the subject is pregnant, prolonged therapy is required or specific organ dysfunction is diagnosed.