1. Target-specific differences in the dendritic morphology and neuropeptide content of neurons in the rat SCG during development and aging.
- Author
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Andrews TJ, Thrasivoulou C, Nesbit W, and Cowen T
- Subjects
- Animals, Autonomic Pathways growth & development, Autonomic Pathways ultrastructure, Cell Size, Cerebral Arteries growth & development, Cerebral Arteries innervation, Dendrites metabolism, Dendrites ultrastructure, Immunohistochemistry, Iris growth & development, Iris innervation, Male, Microscopy, Confocal, Neural Pathways growth & development, Neural Pathways metabolism, Neural Pathways ultrastructure, Neurons metabolism, Neurons ultrastructure, Neuropeptide Y metabolism, Rats, Rats, Sprague-Dawley, Submandibular Gland growth & development, Submandibular Gland innervation, Superior Cervical Ganglion metabolism, Superior Cervical Ganglion ultrastructure, Tyrosine 3-Monooxygenase metabolism, Aging physiology, Dendrites physiology, Neurons physiology, Neuropeptides metabolism, Superior Cervical Ganglion growth & development
- Abstract
Our purpose in this work was to investigate the role of target tissues in the regulation of dendritic morphology from sympathetic neurons during development and aging. Neurons were retrogradely labeled from three targets, the iris, the submandibular gland (SMG), and the middle cerebral artery (MCA). They were then fixed and intracellularly injected to demonstrate their dendritic arborizations. Dendritic geometry varied quantitatively in sympathetic neurons innervating different target tissues at all stages of development. Neurons innervating the iris had the largest cell bodies and most extensive dendritic arborizations, whereas the vasomotor neurons were the smallest. The number of primary dendrites, however, did not vary significantly between the different neuronal populations. The growth of dendritic arborizations during postnatal development and their atrophy in old age were not concordant in the different neuron populations we studied. Neurons innervating the MCA and the iris ceased dendritic growth early in postnatal development, whereas the dendritic complexity of neurons supplying the SMG increased well into adulthood. By contrast, dendritic atrophy was seen in aged MCA- and SMG-projecting neurons but not in those innervating the iris, suggesting, with other evidence, correlated and distinct patterns of growth and atrophy in axons and dendrites of mature sympathetic neurons projecting to different targets. Swollen dendrites and protuberances on cell soma were a prominent feature of aged neurons. In addition to the target-specific variation in neuronal morphology, we observed diversity in neurotransmitter phenotype. For example, neuropeptide Y was expressed in iridial but not SMG-projecting neurons. These results show a range of age- and target-specific differences in the dendritic morphology and neuropeptide content of sympathetic neurons that may be a result of differing trophic interactions with their target tissues.
- Published
- 1996
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