CHARACTERIZATION OF NEUROCHEMICAL PHENOTYPES IN CULTURED HYPOTHALAMICNEURONS WITH IMMUNOHISTOCHEMISTRY AND INSITU HYBRIDIZATION

The expression of neurochemical phenotypes was studied in long-term cu ltures of dissociated embryonic neurons from rat hypothalamus. With ti me in culture, these neurons establish a complex dendritic and axonal network, as indicated by staining with antibodies against microtubulin -associated protein (MAP2) and neurofilaments (SMI32 and SMI33) as wel l as GABA and glutamate decarboxylase mRNA immunoreactivity. Neurons e xpressing neuropeptide Y (NPY) mRNA and NPY peptide and opioid-like pe ptides as well as vasopressin were observed. Further, weakly acetylcho linesterase- and NADPH diaphorase (nitric-oxide synthase)-labelled neu rons were present. In conclusion, the neurochemical phenotypes reporte d for hypothalamic neurons in vivo can be observed in these cultures. This indicates that the culture conditions allow morphological and mol ecular differentiation. These findings support the view that long-term hypothalamic cultures provide a valuable model for studying mechanism s of neurosecretion in hypothalamic networks.