Showing papers by "Sanford L. Palay published in 1980"

Hyperinnervation of arrested granule cells produced by the transplantation of monoamine-containing neurons into the fourth ventricle of rat

Abstract: An attempt to learn whether chemically specific neurons affect the sequence of cerebellar development was made by transplanting ectopic tissues rich in monoamines adjacent to the early developing cerebellum of neonatal rat. Three types of brainstem grafts were used: (1) ventral midline raphe region, (2) inferior olivary region, (3) locus coeruleus region. When transplanted into the fourth ventricle of host animals, neurons from the transplant sprout axons into the host cerebellar parenchyma producing changes in cerebellar cytoarchitecture. The changes produced by the three types of brain grafts were investigated with conventional light and electron microscopy. Autoradiography with tritiated serotonin (3H-5HT) and norepinephrine (3H-NE) and immunocytochemistry using antibodies raised against serotonin allowed identification of the chemical specificity of the process. The three fundamental changes caused by the transplants were folial malformation, arrest of migration of external granule cells, and disruption of the Purkinje cell monolayer. By intraventricular infusion of 3H-5HT and immunocytochemistry with antibodies raised against serotonin, an extraordinarily rich serotonin innervation was detected within or around the foci of arrested granule cells after transplantation with raphe-rich tissue. In addition to an increase in the number of parallel fibers that accumulate 3H-5HT, numerous glomerulus-like structures were observed within the foci. After transplantation with locus coeruleus fragments, intraventricular infusion of 3H-NE demonstrated some increase of labeled fibers inside the foci of arrested granule cells, but the extent of the increase of NE fibers was less marked than the increase in 5-HT fibers. Conventional electron microscopic study revealed numerous synaptic formations within the arrested granule cell foci. Terminals containing large granular vesicles were seen, which resemble serotonin nerve terminals previously described (Chan-Palay, 1975, 1977).

Autoradiographic experiments to examine uptake, anterograde and retrograde transport of tritiated serotonin in the mammalian brain.

Abstract: In an attempt to define the potential application of neurotransmitter-specific transport as a method of tracing fiber connections, we have examined the uptake and subsequent ortho- and retrograde transport of tritiumlabeled serotonin (3H-5HT) in the cerebellum-raphe pallidus system. Injection of various concentrations of 3H-5HT followed by different post-injection survival times revealed different labeling patterns in the injected sites and different patterns of transport. The most striking feature is that nonserotonin neurons as well as serotonin cells were able to take up and transport the tritium label in both ortho- and retrograde fashion. The non-sertonin-specific nature of this uptake and transport is more obvious at higher concentrations of 3H-5HT (more than 9x10-5 M), with longer survival times and following pretreatment with monoamine oxidase inhibitors. At a concentration of 9x10-6 M 3H-5HT, only specific uptake seems to take place as evidenced by label in known serotonin cells and fiber systems; however, it was impossible to detect by autoradiography any ortho- or retrograde transport at this low concentration. Non-specific uptake and transport were observed following injection into the vestibular nuclei and oculomotor complex. This suggests that non-specific uptake and the transport of 3H-5HT or metabolites may also occur in other regions of the central nervous system.