Influence of culture conditions on monoamine oxidase A and B activity in rat astrocytes

Abstract

Astroglial cells dispersed from newborn rat hemispheres were established in medium supplemented with 20 per cent fetal calf serum (FBS) and then grown to a confluent monolayer in the presence of 10 per cent FBS or charcoal-stripped FBS (CS). Type 1 astrocytes were subcultured and either maintained under the same conditions of the primary cultures or converted to serum-free chemically defined medium (CDM). No differences were found in either MAO A or MAO B activity of astrocytes grown in the presence of FBS or CS after 15 and 21 days in vitro (day 1 and 6 of subculture). In contrast, on day 21 both MAO A and MAO B activities were markedly higher in astrocytes subcultured in CDM compared with cells maintained in serum-supplemented medium. This difference appeared to be due to increased number of enzyme molecules, since kinetic analysis showed an increase in Vmax of both MAO isoenzymes in serum-free medium, but no change in Km. Consistently, the recovery of MAO A and MAO B activity after irreversible enzyme inhibition by clorgyline and deprenyl was faster in CDM than in FBS-supplemented medium, indicating enhanced enzyme synthesis under serum-free condition. Estimates of half-lives for the recovery of MAO A and MAO B activity indicated that, under both culture conditions, type A activity had a higher turnover rate than type B. The effect of CDM on astrocyte MAO does not appear to be due to selection of a subpopulation of cells, but rather linked to a morphological change (differentiation) with increased synthesis of both MAO isoenzymes.

Attenuation of MPTP‐induced dopaminergic neurotoxicity by TV3326, a cholinesterase‐monoamine oxidase inhibitor

“…This is in contrast to what has consistently been reported for the first order recovery of brain MAO‐A and ‐B activities from inhibition by clorgyline, selegeline and rasagiline (Corte and Tipton 1980; Youdim and Tipton 2002). The latter studies also showed that the half life for recovery of enzyme activity is significantly shorter for MAO‐A than for MAO‐B (Goridis and Neff 1971; Carlo et al . 1996).…”

Astrocytic Adrenoceptors: A Major Drug Target in Neurological and Psychiatric Disorders?

“…The presence of both species of MAO in primary cultures of astrocytes has repeatedly been confirmed [127][128][129], whereas C-6 glioma cells show almost exclusively MAO A activity [130]. Immunocytochemical determination of brain tissue has shown that MAO B is preferentially expressed in astrocytes and in serotonergic neurons [130][131][132], whereas MAO A activity is mainly found in noradrenergic neurons, although it is also expressed in non-neuronal cells [132].…”

Glucocorticoid-Inducible Retrovector for Regulated Transgene Expression in Genetically Engineered Bone Marrow Stromal Cells

“…Flow cytometric analysis was performed within 2 weeks of transduction to ascertain retrovector expression and gene transfer efficiency as measured by GFP fluorescence. Glucocorticoid induction assays were conducted with various dilutions of dexamethasone (SABEX, Boucherville, Quebec, Canada) either in whole medium or in corticosteroid depleted FBS-containing medium that was generated by charcoal stripping (Carlo et al, 1996). Southern blot analysis was perform ed on 15 m g of overnight KpnI-digested genomic DNA extracted from stably transduced cells as well as untransduced control cells.…”