The Journal of Neuroscience, June 15, 2000, 20(12):4740-4744
Social Status Controls Somatostatin Neuron Size and Growth
Hans A.
Hofmann and
Russell D.
Fernald
Neuroscience Program, Stanford University, Stanford, California
94305
Many animal species show flexible behavioral responses to
environmental and social changes. Such responses typically require changes in the neural substrate responsible for particular behavioral states. We have shown previously in the African cichlid fish, Haplochromis burtoni, that changes in social status,
including events such as losing or winning a territorial encounter,
result in changes in somatic growth rate. Here we demonstrate for the first time that changes in social status cause changes in the size of
neurons involved in the control of growth. Specifically, somatostatin-containing neurons in the hypothalamus of H.
burtoni increase up to threefold in volume in dominant and
socially descending animals compared with cell sizes in subordinate and
socially ascending fish. Because somatostatin is known to be an
inhibitor of growth hormone release, the differences in cell size
suggest a possible mechanism to account for the more rapid growth rates
of subordinate and socially ascending animals compared with those of
dominant or socially descending fish. These results reveal possible
mechanisms responsible for socially induced physiological plasticity
that allow animals to shift resources from reproduction to growth or vice versa depending on the social context.
Key words:
cichlid fish; dominance; life history; somatostatin; neuron size; social status; phenotypic plasticity
Copyright © 2000 Society for Neuroscience 0270-6474/00/20124740-05$05.00/0
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