Different uptake of cobalamin (vitamin B₁₂) by astrocytes and oligodendrocytes isolated from rat spinal cord

Abstract

In the present study, we hypothesized that cobalamin (Cbl) deficiency might affect astrocytes and oligodendrocytes of rat spinal cord (SC) differently. Radiolabeled Cbl ([Cyano-14C]cyano-Cbl) was used to investigate whether the in vitro uptake of Cbl is different in primary cultures of oligodendrocytes and astrocytes. In culture medium supplemented with serum that naturally contains Cbl, the time course of labeled Cbl uptake by neonatal oligodendrocytes had two peaks, at 8 h and 24 h. No uptake was observed when the same cells were cultured in a serum-free medium and consequently in the absence of Cbl. Oligodendrocytes isolated from adult rat SC showed no uptake under any of the tested conditions. Astrocytes isolated from adult Cbl-deficient and newborn rat SC, both cultured in a medium supplemented with serum, showed peak Cbl uptake at 8 h and 12 h, respectively, whereas those isolated from the SC of an adult normal rat cultured under the same conditions showed no uptake throughout the experimental period. Astrocytes isolated from normal, Cbl-deficient adult rats and newborns cultured in a serum-free medium not containing Cbl, showed a similar trend of Cbl uptake with a peak at 24 h. Oligodendrocytes isolated from Cbl-deficient rats showed no uptake when cultured in medium with or without serum. This study provides evidence for a difference in the uptake of labeled Cbl between rat SC astrocytes and oligodendrocytes in relation to (1) age of the donor SC, (2) Cbl status of the donor SC, and (3) Cbl deficiency in the incubation medium that facilitates Cbl uptake in neonatal and adult astrocytes.

Cobalamin and normal prions: A new horizon for cobalamin neurotrophism

“…To this aim, it would be interesting to investigate the relationship in cultured astrocytes because: (i) Cbl deficiency has been shown to affect mainly astrocytes morphologically and biochemically [10,99,100], and (ii) PrP C s have been shown to modulate astrocyte functions in vitro [101].…”

Synergy between paclitaxel plus an exogenous methyl donor in the suppression of murine demyelinating diseases

“…The synergistic effect of paclitaxel'/B 12 CN in a mouse type II astrocyte cell line (C8-S) is consistent with this notion. Astrocytes have a much higher capacity to take up vitamin B 12 than oligodendroglia [40], thus promoting astrocyte proliferation and in the given tissue locale, representing a B 12 -sink that generates a progressive, regional cobalamin deficiency. Interestingly, the demonstrated induction of IFN-beta and its signaling pathway would be expected to enhance transcobalamin-II receptor expression, which mediates the cellular uptake of B 12 CN [41], providing yet another level of possible synergy in the two B 12 CN combination therapies now analysed.…”

Biomarkers of folate and vitamin B12 status in cerebrospinal fluid

“…Cultured astrocytes from human brain secrete transcobalamin that is functionally active and can facilitate the cellular uptake of cobalamin (64,65). It has been suggested that transcobalamin is synthesized within the brain.…”