Directed expression of NGF to pancreatic beta cells in transgenic mice leads to selective hyperinnervation of the islets.

Nerve growth factor (NGF) is implicated in the differentiation of neurons in both the central and peripheral nervous systems. As a new approach to its role in neuronal development, we have used transgenic mice to selectively overexpress NGF in an innervated peripheral tissue, the islets of the pancreas. In two lines of mice, directed expression of NGF in the beta cells elicits a dramatic increase in the innervation of the islets, but not the surrounding exocrine tissue, by one class of sympathetic neurons. In contrast, the innervation by sensory and parasympathetic neurons appears unchanged. The results indicate that expression of NGF by a target tissue during neuronal development selectively influences the characteristics of its innervation.