Effects of psychoactive trace minerals on glial cell development in vitro.
Trace minerals are a group of nutritional elements appearing in low concentrations in body tissues. These minerals may have both regulatory and structural functions in the body, and therefore play an important role in human health and well being. Many of these elements have psychiatric actions, including lithium, copper and zinc. Lithium is the most commonly prescribed psychoactive trace mineral, as this is the current preferred treatment for bipolar disorder. The research presented in this thesis has focused on the psychoactive nutritional trace minerals, copper and zinc and how they interact with lithium to affect glioblastoma cell proliferation, function and viability in vitro. Two different glioblastoma cell lines (U87M0 and 132 1N1) were cultured in media containing different concentrations of either zinc or copper above and below the physiological range (0.02 to 10 mgIL copper or 0.2 mg/L to 10 mgIL zinc), in the absence and presence of lithium (1 mg/L). Cell viability was determined using tryptan blue staining. Proliferation rate was determined using both visual counting and an MTT (Methyithiazol tetrazolium) cell proliferation assay. Cell morphology was measured using a standard Harris haematoxylinl eosin-y morphology stain and a computer software package. Cell function was determined by evaluation of cellular resting potential A comparison of two proliferation assays used in this study revealed the MTT assay to be the most accurate and precise. At trace mineral concentrations up to 7.5 mg/L, there were no dose dependent effects of either zinc or copper on cell proliferation, with or without lithium in the culture media. However, at a supraphysiological trace mineral concentration (10 mgIL), U87MG cells appeared to be tolerant to zinc, but sensitive to copper which resulted in marked reductions of cell number (2.91% of control), and cell II viability (24.36% of control). However, 1321N1 cells appeared sensitive to both supraphysiological zinc and copper concentrations with cell viability reduced to 73.63% and 68.63% of control, respectively. Zinc uptake by 132 1N1 cells appears to be highly regulated, and intracellular zinc levels detected using a fluorescent probe were not changed b extracellular medium concentrations of zinc up to 10 mgIL. This tight regulation was perturbed by treatment of cells with therapeutià (1 mgIL) levels of lithium. These results indicate an interaction between lithium and zinc in cell culture which may be of clinical interest if reproducible in other cell types.
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