Social novelty enhances brain cell proliferation, cell survival, and chirp production in an electric fish, Apteronotus leptorhynchus.
For many animals, enriched environments and social interaction promote adult neurogenesis. However, in some cases, the effect is transient, and long-term environmental stimuli have little benefit for neurogenesis. In electric fish, Apteronotus leptorhynchus, fish housed in pairs for 7 days show higher density of newborn brain cells (cell addition) than isolated fish, but fish paired for 14 days have rates of cell addition similar to isolated controls. We examined whether introduction of social novelty can sustain elevated levels of cell addition and prevent long-term habituation to social interaction. We also monitored electrocommunication signals ("chirps") as a measure of the behavioral response to social novelty. We paired fish for 14 days with one continuous partner (no social novelty), two sequential partners changed after 7 days (low novelty) or seven sequential partners changed every 2 days (high novelty). On Day 11, we injected fish with BrdU, sacrificed fish 3 days later and quantified BrdU labeling in the diencephalic periventricular zone. Fish exposed to no novelty had BrdU labeling similar to isolated fish. Fish with low novelty showed small increases in BrdU labeling and those with high novelty had much greater BrdU labeling. Similarly, chirp rates were greater in fish with low novelty than with no novelty and greatest yet in fish with high novelty. By varying the timing of novelty relative to BrdU injection, we showed that social novelty promoted both proliferation and survival of newborn cells. These results indicated that brain cell proliferation and survival is influenced more by social change than simply the presence of social stimuli.
Department of Biology, Trinity College, Hartford, Connecticut 06106, USA. Kent.Dunlap@trincoll.edu
Kent D
KD
Dunlap
Michael
M
Chung
D000819:Animal Communication; D000818:Animals; D000963:Antimetabolites; D001921:Brain / Q000166:cytology* / Q000502:physiology*; D001973:Bromodeoxyuridine; D049109:Cell Proliferation; D002470:Cell Survival / Q000502:physiology; D004555:Electric Fish / Q000502:physiology*; D055724:Electrophysiological Phenomena; D007150:Immunohistochemistry; D008297:Male; D055495:Neurogenesis / Q000502:physiology; D012931:Social Environment; D012934:Social Isolation
D000963:Antimetabolites; D001973:Bromodeoxyuridine