Primary cultures from cerebral cortex and hippocampus enriched in glutamatergic and GABAergic neurons.

The aim was to define a primary culture system enriched in neurons using a defined culture medium, and characterize the model system as to cellular morphology and neuronal phenotypes. We found that these primary neuron enriched cultures from either newborn rat cerebral cortex or hippocampus contain small GABAergic and large glutamatergic neurons as well as astrocytes and microglia. Astrocytes in these cultures are morphologically differentiated with long, slender processes and interact with soluble factors responsible for induction and expression of the glutamate transporter GLT-1. The cultures achieve the highest expression of the vesicular glutamate transporter 1 (VGLUT1) and GLT-1 after 20 days in vitro. Conditioned media from these neuron enriched cultures also induced GLT-1 expression in primary astrocytic cultures, which were free from neurons. The amount of glutamatergic neurons guides the morphological maturation of astrocytes and GLT-1 expression both in the neuron enriched cultures and in the conditioned media supplemented astrocytic cultures. Interestingly, these cultures were not influenced or activated by the inflammatory stimulus lipopolysaccharide. This suggests that soluble factors from neurons protect microglia and astrocytes to become inflammatory reactive. In conclusion we have developed a well characterized culture model system enriched in neurons, taken from newborn rats and cultured in defined media. The neurons express different neuronal phenotypes. Such a model system is valuable when studying interactions between neurons and glial cells.