Effect of chemical environment on levels of substance P and somatostatin in cultured sensory neurones

Abstract

The neurotransmitter produced by autonomic neurones is influenced by the environment in which they develop¹. For example, Le Douarin² and her colleagues have shown that regions of the neural crest which normally give rise to cholinergic ganglia can be induced to develop into adrenergic cells by transplanting them into a region of the crest which normally gives rise to adrenergic ganglia. Similarly, sympathetic neurones grown in culture express either adrenergic or cholinergic properties depending on whether they are grown in the absence or presence of certain types of non-neuronal cells^1,3–5. Patterson et al.^6,7 demonstrated that this is not due to selective survival of a population of neurones but that the transmitter choice of individual neurones can be altered by soluble factors produced by non-neuronal cells. Like autonomic neurones, sensory neurones derive from the neural crest and it therefore seems likely that the type of transmitter they produce could also be influenced by the environment in which they develop. Here I demonstrate that when sensory neurones from embryonic chick dorsal root ganglia are grown together with ganglionic non-neuronal cells or with medium ‘conditioned’ by incubation with such cells, they produce increased amounts of somatostatin (SOM). This increase is neither accompanied by an increase in substance P (SP) content nor a detectable change in neuronal survival and thus differs from the effect of nerve growth factor (NGF), which increases survival of sensory neurones without affecting the relative levels of SOM and SP.