Expression of Manganese Transporters ZIP8, ZIP14, and ZnT10 in Brain Barrier Tissues.

Manganese (Mn) is an essential trace mineral for brain function, but excessive accumulation can cause irreversible nervous system damage, highlighting the need for proper Mn balance. ZIP14, ZnT10, and ZIP8 are key transporters involved in maintaining Mn homeostasis, particularly in the absorption and excretion of Mn in the intestine and liver. However, their roles in the brain are less understood. The blood-cerebrospinal fluid barrier and the blood-brain barrier, formed by the choroid plexus and brain blood vessels, respectively, are critical for brain protection and brain metal homeostasis. This study identified ZIP14 on the choroid plexus epithelium, and ZIP8 and ZnT10 in brain microvascular tissue. We show that despite significant Mn accumulation in the CSF of knockout mice, ZIP14 expression levels in the blood-cerebrospinal fluid barrier remain unchanged, indicating that ZIP14 does not have a compensatory mechanism for regulating Mn uptake in the brain in vivo. Additionally, Mn still enters the CSF without ZIP14 when systemic levels rise. This indicates that alternative transport mechanisms or compensatory pathways ensure Mn balance in the CSF, shedding light on potential strategies for managing Mn-related disorders.