Growth Hormone Enhances Amygdala Spine Density and Fear Memory

Program: Late-Breaking Abstracts
Session: LBSU 0377-0378-Growth Hormone Signaling
Translational
Sunday, June 22, 2014: 1:00 PM-3:00 PM
Hall F (McCormick Place West Building)

Poster Board LBSU-0378
Ki Goosens, PhD, Barbara Gisabella and Jessica Brophy
McGovern Institute, Massachusetts Institute of Technology, Cambridge, MA
Growth hormone (GH) exerts pronounced trophic effects in many tissues throughout the body. Although GH is synthesized by the pituitary gland, where it is released into the circulating bloodstream, it is also synthesized within limbic brain areas including the amygdala and the hippocampus, two brain regions that regulate emotional memory. However, very little is known about the role of locally synthesized GH in regulating emotional processing.  Recent studies show that GH expression is enhanced in the amygdala by chronic stress, and is both necessary and sufficient for chronic stress-related enhancement of fear memory in rodents, an animal model of post-traumatic stress disorder (PTSD)1. Despite our understanding of GH signaling in the periphery, it is not clear how GH acts in the amygdala to enhance associative fear learning. One possibility is that, just as GH produces trophic effects in the periphery, it may exert similar trophic effects in the brain.  

To explore the hypothesis that GH produces neurotrophic effects in the adult brain, we used an adeno-associated viral vector to overexpress GH with green florescent protein (GFP) or GFP alone in the basolateral complex of the amygdala (BLA) in rats. Dendritic spines were quantified by combining confocal imaging with three-dimensional dendritic analysis.  We found that growth hormone overexpression significantly enhanced density of dendritic spines on both primary and secondary branches of pyramidal neurons in the BLA.

This suggests that GH potently promotes dendritic spinogenesis in neurons, illuminating a novel role for GH in the adult brain, and provides a potential mechanism by which chronic stress, which enhances GH in the amygdala, could contribute to stress-induced alterations in amygdala morphology and function.

This research was funded by NIMH (R01 MH084966), and the U.S. Army Research Office and the Defense Advanced Research Projects Agency (grant W911NF-10-1-0059) to KAG.

Nothing to Disclose: KG, BG, JB

*Please take note of The Endocrine Society's News Embargo Policy at https://www.endocrine.org/news-room/endo-annual-meeting

Sources of Research Support: 1) Meyer RM, Burgos-Robles A, Liu E, Correia SS, Goosens KA. (2013) A ghrelin-growth hormone axis drives stress-induced vulnerability to enhanced fear. Mol Psychiatry. doi: 10.1038/mp.2013.135.
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