Journal of Neuroscience, Vol 13, 434-441, Copyright © 1993 by Society for Neuroscience
Gonadotropin-releasing hormone-containing neurons change size with reproductive state in female Haplochromis burtoni
SA White and RD Fernald
Neuroscience Program, Stanford University School of Medicine, California 94305-2130.
In the preoptico-hypothalamic area (POA) of teleost fish, neurons
containing gonadotropin-releasing hormone (GnRH) regulate reproduction
through direct projections to pituitary gonadotropes. Here we show that
these GnRH-containing cells change size depending on the reproductive and
maturational state in female Haplochromis burtoni. We selected animals
prior to, during, and after the reproductive portion of their life history,
in both brooding and spawning states. Immunocytochemical staining of
GnRH-containing neurons in the POA revealed that these cells are up to
twice as large in females that have never spawned or are in the act of
spawning than they are in females that are carrying broods. Older,
postreproductive females have the largest cell sizes. Previous work on male
H. burtoni has shown that soma sizes of the homologous neurons change
according to social status, with dominant fish having larger cells than
subordinates. Since reproductively active females have no apparent social
hierarchy and are all exposed to approximately the same external stimuli,
the primary factor(s) controlling GnRH-immunoreactive (irGnRH) neuron size
appears to be internal reproductive state. Thus, while irGnRH neurons are
pleiomorphic in both males and females, cell size change is differently
regulated in each.
Previous Article | Next Article
