Properties of dopaminergic neurons in organotypic mesencephalic-striatal co-cultures--evidence for a facilitatory effect of XXXX on the glutamatergic input mediated by a-1 adrenergic receptors.

@entity19 @entity669 @entity935 @entity2227
Organotypic cultures (OCs) have been widely used to investigate the midbrain dopaminergic system, but only a few studies focused on the functional properties of dopaminergic neurons and their synaptic inputs from dopaminergic and non-dopaminergic neurons also contained in such cultures. In addition, it is not clear whether the culturing process affects the intrinsic neuronal properties and the expression of specific receptors and transporters. We performed patch-clamp recordings from dopaminergic neurons in mesencephalic-striatal co-cultures obtained from @entity19 expressing green fluorescent protein (GFP) under the @entity669 hydroxylase promoter. Some (10/44) GFP+ neurons displayed a bursting activity that renders the firing of these cells similar to that of the dopaminergic neurons in vivo. The culturing process reduced the hyperpolarization-activated current (I(h) ) and the expression of D    receptors. Downregulation of D    receptor mRNA and protein was confirmed with reverse transcriptase polymerase chain reaction and Western blotting. Immunocytochemistry revealed that many synaptic terminals, most likely originating from dopaminergic neurons, co-expressed the @entity935 (DA) transporter and the vesicular @entity2227 transporter-2, suggesting a co-release of DA and @entity2227 . Interestingly, exogenous DA decreased @entity2227 release in young cultures [days in vitro (DIV)<20] by acting on pre-synaptic D    receptors, while in older cultures (DIV>26) DA increased @entity2227 release by acting on a-1 adrenoreceptors. The facilitatory effect of DA on glutamatergic transmission to midbrain dopaminergic neurons may be important in conditions when the expression of D    receptors is compromised, such as long-term treatment with antipsychotic drugs. Our data show that midbrain OCs at DIV>26 may provide a suitable model of such conditions.
