Control of the maturation and the survival of central noradrenergic neurons in culture.

Abstract

Central noradrenergic neurons from the locus coeruleus express unique plastic properties. The aim of this study was to identify factors that specifically regulate the development and the survival of the noradrenergic cells. Primary dissociated cultures of embryonic locus coeruleus (LC) neurons were established. Norepinephrine (NE) uptake was used as an index of maturation of the noradrenergic neurons. The noradrenergic cells were identified and quantified following immunocytochemical staining for tyrosine hydroxylase antibody. We have examined the effect of hippocampal target tissue and of cyclic-AMP (cAMP) on the development of these cells. Coculturing LC cells with a low density of hippocampal target cells, resulted in a significant increase in NE uptake. However, when the amount of hippocampal target cells was doubled an enormous decrease in NE uptake occurred. The target stimulatory effect was mediated by both neurons and glia, whereas the inhibitory effect was mediated by direct contact between target glia and LC neurons and detected only in the presence of serum. In addition to target effect, we also tested the effect of elevated intracellular cAMP level on NE uptake versus GABA uptake. GABA uptake served as a developmental index of the non noradrenergic cells. Increasing the intracellular cAMP level, by application of the membrane permeable analog dibutyryl cyclic AMP (DbcAMP), resulted in a selective stimulation of NE uptake, due to enhanced survival of noradrenergic neurons. GABA uptake and the number of non-noradrenergic cells were not changed in the presence of DbcAMP. DbcAMP could maintain the survival of LC neurons in the absence of glial cells.(ABSTRACT TRUNCATED AT 250 WORDS)