SLICE CULTURES OF THE IMPRINTING-RELEVANT FOREBRAIN AREA MEDIO-ROSTRAL NEOSTRIATUM HYPERSTRIATUM VENTRALE OF THE DOMESTIC CHICK - IMMUNOCYTOCHEMICAL CHARACTERIZATION OF NEURONS CONTAINING CA2-BINDING PROTEINS()

The forebrain area medio-rostral neostriatum/hyperstriatum ventrale, a presumed analogue to the mammalian prefrontal cortex, displays a vari ety of synaptic changes during auditory filial imprinting. In order to study the underlying basic mechanisms of this synaptic plasticity we developed slice cultures of the medio-rostral neostriatum/hyperstriatu m ventrale from newly hatched chicks. As a prerequisite for these inve stigations and in order to test the suitability of this system for fut ure studies, we performed a thorough characterization of the in vitro tissue, of its cellular components and some of their biochemical featu res in comparison with in situ tissue. Since in situ the medio-rostral neostriatum/hyperstriatum ventrale has been previously shown to conta in three distinct neuron populations characterized by the activity-reg ulated Ca2+-binding proteins parvalbumin, calbindin D28K and calretini n, we used these proteins as neuronal markers to study the survival an d preservation of the morphological features of medio-rostral neostria tum/hyperstriatum ventrale neurons in vitro, In agreement with in vivo studies the three Ca2+-binding proteins are confined to neuronal cell s and they are not colocalized, i.e, they appear to characterize three different neuron populations. The immunoreactive neurons in medio-ros tral neostriatum/hyperstriatum ventrale cultures to a certain extent a ppear to form synaptic contacts with each other, shown by the double i mmuncytochemical experiments, One difference between cells in vivo and in vitro is their soma size, which is much larger in vitro than in vi vo, This and our previous study on neuronal morphology demonstrates th at morphologically and biochemically intact neurons can be maintained in medio-rostral neostriatum/hyperstriatum ventrale slice cultures, wh ich may thus provide a suitable in vitro system for further studies of neuronal and synaptic plasticity in vitro.