Rescue of both rapidly and slowly degenerating neurons in the dorsal lateral geniculate nucleus of adult rats by a cortically derived neuron survival factor.
We investigated the death of dorsal lateral geniculate nucleus (dLGN) neurons after lesions to the visual cortex of adult rats and the effects of supplying target-derived neurotrophic molecules to the lesion cavity. The neurotrophic factor is retrieved from cocultures of the embryonic primordia of the geniculocortical pathway and its survival promoting properties for different populations of dLGN neurons (based on their time of origin) have been documented in previous studies of neonatal rats with occipital cortex lesions. In the present study, rats were exposed to [3H]thymidine on E14 or E15/16 to label either earlier or later generated dLGN neurons. When animals were at least 45 days old we made discrete lesions to the principal projection zones in area 17 of these two dLGN populations. Counts of surviving labeled cells show a relatively rapid death of E15/16 dLGN neurons in control animals, with a maximal loss by 2 weeks postlesion. The death of E14 dLGN neurons is more protracted, with a maximal loss by 2 months postlesion. A 2-week infusion of the CM fraction rescues the majority of the neurons that would otherwise die in both populations compared to the controls which receive a similarly prepared fraction of unconditioned medium. Moreover, this CM fraction can sustain E14-generated dLGN neurons up to 6 weeks after the neurotrophic factor(s) is no longer being supplied exogenously. Thus the rescue of axotomized adult dLGN neurons appears to be permanent, at least for the early generated population. These findings are consistent with the idea that target-derived molecules have a role in the survival of mature neurons, as they are known to have for developing neurons.(ABSTRACT TRUNCATED AT 250 WORDS)
Eagleson
K L
KL
Department of Anatomy and Neurobiology, Medical College of Pennsylvania, Philadelphia 19129.
Cunningham
T J
TJ
Haun
F
F
D000818:Animals; D016923:Cell Death; D002540:Cerebral Cortex / Q000378:metabolism*; D003470:Culture Media; D005829:Geniculate Bodies / Q000473:pathology*; D009410:Nerve Degeneration / Q000187:drug effects*; D009414:Nerve Growth Factors / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000378:metabolism / Q000494:pharmacology*; D009474:Neurons / Q000473:pathology / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D014793:Visual Cortex / Q000473:pathology
D003470:Culture Media; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins