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Stimulation of Serotonergic Neuronal Maturation after Fetal Mesencephalic Raphe Transplantation into the 5,7‐DHT‐lesioned Hippocampus of the Adult Rat a
Author(s) -
ZHOU F. C.,
AUERBACH S. B.,
AZMITIA E. C.
Publication year - 1987
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.1987.tb23672.x
Subject(s) - transplantation , library science , neuroscience , gerontology , medicine , biology , computer science
Neurotoxin lesioning of 5-HT fibers selectively induced the homotypic collateral sprouting of spared 5-HT fibers in the hippocampus. We have used this model to investigate the possibility that the neurotoxin-primed hippocampus will enhance the development of transplanted fetal serotonergic neurons in the brain. The neurotoxin 5,7-DHT, when microinjected into the FF, produced a specific and partial depletion of 5-HT in the hippocampus of adult rats. The ability of the 5,7-DHT-primed hippocampus to selectively support the neurochemical maturation of fetal serotonergic cells was tested by assaying the transplanted fetal raphe or LC 1 month after neuronal transplantation. The neurochemical maturation of fetal 5-HT and NE neurons was dramatically different when they were transplanted in the 5,7-DHT-FF-lesioned hippocampus as compared to the normal hippocampus. The transplanted 5-HT neurons had 480% more SHAU of [3H]5-HT and had a 250% greater content of 5-HT in the partially denervated hippocampus than in the normal hippocampus after 1 month. Furthermore, extracts obtained from lesioned hippocampus enhanced the 5-HT content of 5-HT neurons transplanted in the normal hippocampus, to a level similar to that seen in neurons transplanted in the lesioned hippocampus. In contrast, the implanted NE neurons of fetal LC had a lower NE level in the 5-HT partially denervated hippocampus than in normal hippocampus after 1 month in the host site. The growth of the NE transplants was not facilitated by the vacant postsynaptic space produced by the 5,7-DHT lesion. These results suggest that the 5-HT denervation triggered a trophic signal selectively enhancing the development of the 5-HT neurons but not the NE neurons. Our results are consistent with previous studies showing homotypic collateral sprouting in 5,7-DHT-primed hippocampus.