Depression is a leading cause of disability worldwide, yet available treatments are ineffective for nearly half of treated patients. Depression has been linked to early life adversity and is exacerbated by stress, so uncovering how stress affects mood-related brain regions is critical to improve our understanding of depression etiology and potentially improving treatment. Depression patients often display reduced hippocampal volume, and many animal models of depression display a reduction in hippocampal neurogenesis that is reversed by chronic exposure to antidepressants. Using a pig and mouse model, we were able to examine the effects of early life adversity on adult neurogenesis, and mast cell FosB on behaviors respectively. Our examination of female, castrated male, and intact male pigs, who underwent either early weaning or late weaning allowed us to see not only the effects of early life adversity, but any possible sex-specific effects as well. We found that early weaned female pigs expressed a significantly reduced number of new neurons in their hippocampi compared to their late weaned counterparts. Using a transgenic mouse model which had FosB floxed out of all mast cells, we observed the behavioral outcomes in various assays, including social interaction, elevated plus maze, and sucrose preference. We found that male mice homozygous for the mutation had a significantly increased preference for sucrose compared to the wildtype mice.
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