Poster Presentation The International Congress of Neuroendocrinology 2014

Status differences in gonadotropin inhibitory hormone (GnIH) in the naked mole-rat brain (#357)

Deane E Peragine 1 , Natasha R Douglas 1 , Lucia Mendoza-Viveros 2 , Hai-Ying M Cheng 2 , George E Bentley 3 , Melissa M Holmes 1 2
  1. Department of Psychology, University of Toronto Mississauga, Mississauga, Ontario, CA
  2. Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, CA
  3. Department of Integrative Biology and Helen Wills Neuroscience Institute, University of California at Berkeley, Berkeley, California, USA

Naked mole-rats are eusocial mammals, living in large colonies with strict social and reproductive hierarchies. Within each colony, reproduction is restricted to a single dominant female and 1-3 dominant males; all other colony members are socially subordinate and reproductively suppressed. Gonadotropin inhibitory hormone (GnIH) is a neuropeptide that regulates reproduction in vertebrates and GnIH expression can be altered by changes in social environment. We hypothesized that GnIH is a key regulator of reproductive suppression in naked mole-rats. To begin to test this, we compared GnIH immunofluorescence in the brains of adult breeders and subordinates (n = 3). Naked mole-rats exhibit GnIH fiber immunoreactivity in the dorsomedial hypothalamus, preoptic area, bed nucleus of the stria terminalis, anteroventral paraventricular nucleus, and posterior portion of the lateral septum. Immunofluorescent cell bodies are seen in the dorsomedial hypothalamus and arcuate nucleus. We first measured relative intensity of fluorescence in the paraventricular nucleus and arcuate nucleus. As predicted, subordinates had significantly greater staining intensity in the PVN (p = 0.039) and the arcuate nucleus (p < 0.001) than breeders. Qualitative analyses indicate a similar pattern in other brain areas. Future work will quantify GnIH  immunofluorescence in additional regions as well as distinguish between labeled fibers and cell bodies. These preliminary results are consistent with a role for GnIH in socially-induced reproductive suppression in eusocial naked mole-rats.