Heterogeneity of GABAA receptor-mediated responses in the human IMR-32 neuroblastoma cell line

Abstract

The gamma-aminobutyric acid (GABA) response profiles of IMR-32 human neuroblastoma cells were examined using whole-cell patch clamp and RT-PCR techniques. GABA activated a concentration-dependent and bicuculline-sensitive current, and RT-PCR revealed the expression of multiple GABA(A) receptor subunit mRNAs (alpha(1), alpha(3), alpha(4), beta(1), beta(3), gamma(2), and delta). A pharmacological profile of the GABA-induced current was derived using several subunit-selective agents. Diazepam, which requires the presence of a gamma subunit in order to modulate GABA(A) receptor-mediated responses, potentiated GABA-induced currents in a subset of IMR-32 cells. Two populations of GABA-activated currents were also evident based on sensitivity to modulation by zinc. Comparison of zinc- and diazepam-induced modulation of GABA-induced current responses in the same cells revealed an inverse correlation between these two modulators. No differences, however, were observed with the GABA(A) receptor modulators loreclezole, allopregnanolone, and pentobarbital. Thus, IMR-32 cells maintained in culture are heterogeneous in terms of expression of GABA(A) receptor isoforms.

Expression levels of the α4 subunit of the GABAA receptor in differentiated neuroblastoma cells are correlated with GABA-gated current

“…For the present study, we employed a human neuroblastoma cell line, IMR-32 (Sapp and Yeh, 2000), which we have shown (Zhou and Smith 2007), following neuronal differentiation, is an effective model to investigate upregulation of the GABAR α4 subunit following 48 h THP treatment. It also provides a homogeneous population of cells to investigate GABAR expression, unlike traditional neuronal cell culture.…”

“…These possibilities were investigated using a pharmacological approach with selective GABA ligands to increase or decrease GABA-gated current or by altering the Cl − driving force without direct interaction with the GABAR. To this end, we used NGF-differentiated IMR-32 cells, which express GABAR and have been characterized pharmacologically (Sapp and Yeh, 2000), and which we have previously shown (Zhou and Smith, 2007) are an optimal system for THP-induced upregulation of the GABAR α4 subunit. In addition, we chose a neuroblastoma cell line because it represents a homogeneous population of cells, unlike primary neuronal cell cultures.…”

Anisotropically Conductive Biodegradable Scaffold with Coaxially Aligned Carbon Nanotubes for Directional Regeneration of Peripheral Nerves

“…The functional characterization of the scaffolds involved different types of biological assays. Human peripheral neuroblastoma cells, IMR-32, possessing important functional modulators of the peripheral nervous system (PNS), namely, GABA (A), GABA (B), and insulin receptors, procured from NCCS, Pune, India, were used for in vitro studies. , Similarly, the sciatic nerve injury model, a well-established model for studying recovery from PNI and PNS regeneration, was used for in vivo studies. , …”