Distribution of neuronal receptors for nerve growth factor in the rat

To survey the distribution of neuronal receptors for NGF, sections of the rat brain, spinal cord, and peripheral ganglia were incubated in vitro with radioiodinated NGF and examined by autoradiography. NGF binds selectively with high affinity to most sympathetic neurons and many primary sensory neurons together with their intraspinal or intramedullary axons. In autoradiographs of the brain, labeled neuronal perikarya are seen in the basal forebrain, the caudate-putamen, the medulla oblongata, the ventral cochlear nucleus, and the dorsal nucleus of the lateral lemniscus. The distribution of neurons binding NGF resembles the distribution of cholinergic neurons in the forebrain, but these 2 systems overlap very little in the brain stem. In extracts of the brain or spinal cord enriched for plasma membranes, avid binding sites are regionally manifest with properties similar to those of fetal peripheral neurons. The localization of neurons expressing the high-affinity receptor for NGF defies simple correlation with neurotransmitter function or embryogenesis.