Neuron/glia relationships observed over intervals of several months in living mice.

Abstract

Abstract. Identified neurons and glial cells in a parasympathetic ganglion were observed in situ with video-enhanced microscopy at intervals of up to 130 d in adult mice. Whereas the number and position of glial cells associated with particular neurons did not change over several hours, progressive differences were evident over intervals of weeks to months. These changes involved differences in the location of gliai nuclei on the neuronal surface, differences in the apparent number of glial nuclei associated with each neuron, and often both. When we examined the arrangement of neurons and glial cells in the electron microscope, we also found that presynaptic nerve terminals are more prevalent in the vicinity of glial nuclei than elsewhere on the neuronal surface. The fact that glial nuclei are associated with preganglionic endings, together with the finding that the position and number of glial nuclei associated with identified neurons gradually changes, is in accord with the recent observation that synapses on these neurons are normally subject to ongoing rearrangement (Purves, D., J. T. Voyvodic, L. Magrassi, and H. Yawo. 1987. 238:1122-1126). By the same token, the present results suggest that glial cells are involved in synaptic remodeling. Science (Wash. DC). N'EURONS are invariably associated with glial cells. In some instances, the functional significance of the association is clear, as in the case of axon myelination by Schwann cells or oligodendrocytes (Wood and Bunge, 1984;Bunge, 1986). In most instances, however, the functional role of glia is less clear; certainly, this is true in mammalian autonomic ganglia, in which the principal neurons are invested by gila called satellite cells (Gabella, 1976;Pannese, 1981).In the present report, we have examined glial cells in a mouse autonomic ganglion with the aim of assessing the normal plasticity of the relationship between neurons and gila. In carrying out this work, we have taken advantage of the relatively simple structure of mouse salivary duct ganglia to monitor selected neurons and their associated glial cells over intervals of up to several months in situ. Using the same techniques previously used to follow individual neurons and their synaptic contacts over time , we evaluated the number and position of glial cells associated with identified neurons as a function of the interval between observations. Our results indicate that the relationship between neurons and glial cells gradually changes. Moreover, when we examined these cells with the electron microscope, we found that preganglionic terminals are preferentially located in the vicinity of glial nuclei. The prevalence of synapPortions of this work have appeared in abstract form (1987. Soc. Neurosci. ,4bstr. 13:1008 ses near glial nuclei, taken together with the observation that glial nuclear position gradually changes, implies that glial cells are active participants in the process of synaptic rearrangement. Materials and MethodsYoung adult male mice (CF1 strain; 25-30 g) were anesthetized with ...

Fluorescent Proteins Expressed in Mouse Transgenic Lines Mark Subsets of Glia, Neurons, Macrophages, and Dendritic Cells for Vital Examination

“…Our observations extend to the glial components of the synapse the relative stability previously reported for the nerve terminal and postsynaptic apparatus at adult NMJs (Balice- Gordon and Lichtman, 1990). This finding contrasts with variability in glial cell numbers and positions observed during vital imaging of synapses in parasympathetic ganglia (Pomeroy and Purves, 1988), but these synapses are more dynamic than neuromuscular junctions.…”

Thrombin‐induced reversal of astrocyte stellation is mediated by activation of protein kinase C β‐1

“…It is known that glial cells promote synapse formation in vitro (Skoff, 1990;Panavelas et al, 1983;O'Lague et al, 1978). Different observations suggest that glial cells migrate and grow to maintain their spatial relationship with synapses in vivo (Pomeroy and Purves, 1988;Hawrylak et al, 1993). This implies a potential involvement of glia during the development and remodeling of synaptic connections.…”

Nerve Terminal Withdrawal from Rat Neuromuscular Junctions Induced by Neuregulin and Schwann Cells

“…Changes in the morphology and position of Schwann cells have been correlated with synapse elimination and nerve terminal remodeling in the peripheral nervous system (Matthews and Nelson, 1975;Riley, 1981;Pomeroy and Purves, 1988;. As such, we examined whether the changes in terminal SC s in GGF2-treated muscles were correlated with the retraction of nerve terminal branches.…”