Research progress of manganese exposure on abnormal GnRH release in hypothalamus affecting reproductive function

Manganese plays an important physiological role in the organism, and excessive manganese exposure can cause impairment of neurological and reproductive functions. Gonadotropin-releasing hormone secreted by the hypothalamus acts as an initiator to regulate reproductive functions, such as gonadal development, onset of puberty, and gonadal hormone release. But the mechanism by which manganese damages the hypothalamus leading to abnormal gonadotropin-releasing hormone release is still unclear yet. Kisspeptin, prostaglandin E₂, and nitric oxide may act as stimulators to increase the release of gonadotropin-releasing hormone, while the stimulatory or inhibitory effect of γ-aminobutyric acid on the release of gonadotropin-releasing hormone is controversial. Based on current research, manganese has been less studied with Kisspeptin, and studies with prostaglandin E₂, nitric oxide, and γ-aminobutyric acid mainly focused on inflammation, oxidative stress, and neurotransmitter transmission. Therefore, taking Kisspeptin, prostaglandin E₂, γ-aminobutyric acid, and nitric oxide as the breakthrough points, this paper introduced the mechanism of manganese affecting the release of gonadotropin-releasing hormone in the hypothalamus through the above four pathways, and proposed that the abnormal release of gonadotropin-releasing hormone in the hypothalamus may be one of the mechanisms by which manganese regulates reproductive function, providing a new direction for the prevention and treatment of manganese-induced reproductive damage in the future.