Benzodiazepine Receptor Development in Murine Glial Cultures

Abstract

Benzodiazepine (BDZ) receptor binding characteristics were determined from glial cultures prepared from the cerebral hemispheres of newborn mice. Receptor binding and saturation analyses were performed at various ages in culture on intact cells. Utilizing 5 nM³H-diazepam at 0.4°C, specific binding reached a plateau at 16–21 days after plating. A single high-affinity binding site was identified with K_d 25.3 ± 2.6 nM and B_max 7,575 ± 410 fmol/mg protein. Inhibition studies utilizing clonazepam indicated that this ligand, thought to have affinity exclusively for neurons, displaces more than 20% of the specific BDZ binding at concentrations as low as 300 nM, although the IC₅₀ was 1.5–2.0 µM. In contrast, the IC₅₀ for Ro5–4864 was 10–20 nM.

Tis gene expression in cultured rat astrocytes: Multiple pathways of induction by mitogens

“…Other TIS genes had similar responses in PC12 cells to BZD alone or BZD plus NGF (Kujubu et al, 1987). Astrocytes possess high-affinity binding sites for the peripherally active benzodiazepine Ro5-4864 (Schoemaker et al, 1983;Bender and Hertz, 1985;Talwar and Sher, 1987). This ligand enhances GABA-induced astrocyte depolarization (Backus et al, 1988) and inhibits astrocyte proliferation (Pawlikoski et al, 1988).…”

“…BZD are reported to alter glial physiology. In particular, Ro5-4864 (p-chlorodiazepam) (Pellow and File, 1984), a peripherally active BZD, binds with high affinity to astrocytes and astrocytoma cell lines (Schoemaker et al, 1983;Bender and Hertz, 1985;Talwar and Sher, 1987). A recent report demonstrates that BZD inhibits the proliferation of glioma cells (Pawlikoski et al, 1988).…”

Peripheral benzodiazepine receptors: on mice and human brain imaging

“…In addition to the limited neuronal localization, many investigations clearly demonstrated high levels of PBR in cultured astrocytes (Ducis et al . 1990) and primary glial cells (Talwar and Sher 1987). Thus, ω3 sites monitoring using various binding techniques (to either brain slices or membrane fragments) with specific ligands (e.g.…”

Effects of transforming growth factor-beta on murine astrocyte glutamine synthetase activity. Implications in neuronal injury.

“…The primary murine astroglial cultures were established after dispersion of BALB/c neonatal (< 24 h ofbirth) cerebral cortices with trypsin (0.25%) for 30 min, as previously described (24). Briefly, cells (2.4 x 105/300 til) were plated into wells of 24-well plates with DME containing 10% heat-inactivated FCS (Hyclone Laboratories Inc., Logan, UT) and antibiotics, and were then incubated at 370C with 10% CO2.…”

“…On day 9, astrocyte cultures were treated with TGF-#2 (from 1 pg/ml to 5 ng/ml) for 3,8,24, and 48 h before harvest for determination of GS activity. ED5o ofTGF-,B inhibition ofGS activity was determined at 24 h based on these doses.…”