Zinc (Zn) deficiency is present in many physiological and health problems. Among
circumstances involved in Zn deficiency, ethanol consumption appears as a prominent
cause. In the CNS substantial amounts of Zn appear accumulated in synaptic vesicles of a
particular class of neurons: the Zn enriched neurons very abundant in the telencephalon and
cerebral cortex. This is the so called synaptic Zn which is simultaneously released with the
neurotransmitter thus exerting a neuromodulator role during synaptic transmission.
Neighbour astrocytic processes have to capture the excess of both extracellular Zn and
neurotransmitter in order to maintain efficient synaptic transmission between neurons. In this
work we analyze the effect of exposure to 30 mM ethanol for 7 days in the ability of cultured
rat astrocytes to capture and manage extracellular Zn. Intracellular Zn levels were visualized
by using the TSQ Zn fluorochrome, either in normal culture conditions or after supplementary
addition of 50 μM ZnSO4 to the culture. Fluorescence was recorded with an Olympus
microscope BX50WI, equipped with a Hamamatsu ORCA digital camera controlled with the
Aquacosmos software. Basal Zn levels in cultured astrocytes was greatly and significantly
lower in ethanol treated cells (about 30% of control cultures). These differences were
consistently maintained after addition of extracellular Zn to cell monolayers, resulting in a
lower ability to uptake or retain Zn. The Zn was uptaked by the endocytic pathway, as
demonstrated by the marker FM1-43 and was mainly confined to bright organelles that were
more abundant in control cells. In conclusion, ethanol impairs astrocyte Zn management
resulting in a lower capacity for extracellular Zn intake in resting conditions and after
extracellular addition. It has been proposed that an efficient method to palliate Zn deficiency
it could be a dietary supplement. Nevertheless, this study suggests that a dietary Zn
supplementation may not be enough for recovery of cellular normal function in alcoholic
cultured astrocytes
