Differences in the regulation of BDNF and NGF synthesis in cultured neonatal rat astrocytes

Abstract

Using a new brain-derived neurotrophic factor (BDNF) specific enzyme-immunoassay, we determined the basal cellular content of BDNF protein in neonatal rat astrocytes in primary culture, thus confirming the ability of astrocytes to synthesize BDNF in addition to nerve growth factor (NGF). We subsequently monitored the influence of different pharmacological agents: neurotransmitter receptor agonists, cytokines, and second messenger up-regulators, on the synthesis of BDNF and NGF. Marked differences in the regulation of their synthesis by the above pharmacological agents were observed in our study. The basal cellular levels of BDNF protein in cultured neonatal rat cortical and cerebellar astrocytes were 15.9 +/- 0.3 and 18.7 +/- 0.4 pg BDNF/mg cell protein, respectively, and differ significantly between astrocytes from different brain regions, whereas NGF levels were the same (16.1 +/- 0.3 and 16.2 +/- 0.7 pg NGF/mg cell protein, respectively). Screening different neurotransmitter systems for their influence on BDNF and NGF synthesis in cortical astrocytes revealed that dopamine (0.15 mM) is a potent up-regulator of BDNF protein synthesis in astrocytes, while kainic acid (50 microM) and histamine (1 microM) did not raise the cellular level of BDNF protein. Dopamine had no influence on NGF synthesis, while kainic acid caused minor, and histamine marked, elevation of NGF cellular content. Tumor necrosis factor-alpha (30 ng/ml) and interleukin-1beta (10 U/ml) treatments did not influence BDNF synthesis, whereas they markedly increased NGF protein cellular level. We also confirmed (using forskolin (20 microM) and phorbol 12-myristate 13-acetate (TPA) (100 nM)) that adenylate cyclase and protein kinase C participate in the downstream signaling responsible for the stimulation of BDNF synthesis, whereas in the regulation of NGF synthesis only the participation of protein kinase C was confirmed. Our results indicate that astrocyte-derived neurotrophins could play a role in distinct brain functions under physiological conditions and in the pathogenesis as well as possible treatment of different neurodegenerative disorders.

Time-dependent contribution of non neuronal cells to BDNF production after ischemic stroke in rats

“…However, evidences from in vitro studies using cells cultured in conditions mimicking ischemia reveal that these factors are multiple. For instance, astrocytes express BDNF when dopamine, glutamate or cytokines are added to the culture medium (Jean et al, 2008;Miklic et al, 2004;Saha et al, 2006). Human cerebral endothelial cells produce substantial amount of BDNF when exposed to pro-inflammatory conditions and to reduced oxygen avaibility (Bayas et al, 2002;Wang et al, 2006), and microglial cells respond to media from damaged neurons by BDNF upregulation (Lai and Todd, 2008).…”

“…Because increased levels of BDNF mRNA were observed in degenerating and surviving neurons in the acute post-stroke period (Comelli et al, 1992;Kokaia et al, 1995;Rickhag et al, 2007;Zhao et al, 2000), it has been generally accepted that neurons are the predominant source of neosynthesized BDNF in the ischemic brain. However, the contribution of non neuronal cells is suspected from in vitro studies that report the ability of microglial cells, cerebral endothelial cells and astrocytes to express and secrete BDNF when exposed to conditions mimicking ischemia (Bayas et al, 2002;Jean et al, 2008;Lai and Todd, 2008;Miklic et al, 2004;Saha et al, 2006). In vivo, data reported BDNF expression by non neuronal cells such as astrocytes (Sato et al, 2009;Uchida et al 2010) or microglia (Batchelor et al, 1999;Madinier et al, 2009;Nagamoto-Combs et al, 2007) but, to the best of our knowledge, studies specifically designed to assess their exact contribution to BDNF production are lacking.…”

Nerve Growth Factor Is Regulated by Toll-Like Receptor 2 in Human Intervertebral Discs

“…However, NGF synthesis has been investigated in other tissues including the central nervous system. In astrocytes, PKC activation was associated with increased NGF, whereas increased cAMP levels did not affect NGF expression (48). In astrocytoma cells, c-fos activation increases NGF and inhibiting c-fos-reduced ␤-adrenergic receptor activation of NGF (49).…”

Voluntary exercise or amphetamine treatment, but not the combination, increases hippocampal brain-derived neurotrophic factor and synapsin I following cortical contusion injury in rats

“…However, BDNF elevations with AMPH treatment could also be related to drug-induced increases of 5-HT and DA. Monoaminergic activity, which is elevated with AMPH, has been found to enhance the expression of BDNF (Fumagalli et al, 2003;Mattson et al, 2004;Miklic et al, 2004;Juric et al, 2006;Luellen et al, 2007). A third putative mechanism for AMPH to increase BDNF is through the cocaine-and amphetamine-regulated transcript (CART).…”