Social stress increases plasma cortisol and reduces forebrain cell proliferation in subordinate male zebrafish (Danio rerio) [RESEARCH ARTICLE]

Jonathan Tea, Sarah L. Alderman, and Kathleen M. Gilmour Many animals, including zebrafish (Danio rerio), form social hierarchies through competition for limited resources. Socially subordinate fish may experience chronic stress, leading to prolonged elevation of the glucocorticoid stress hormone cortisol. Since elevated cortisol levels can impair neurogenesis, the present study tested the hypothesis that social stress suppresses cell proliferation in the telencephalon of subordinate zebrafish via a cortisol-mediated mechanism. Cell proliferation was assessed using incorporation of the thymidine analogue, 5-bromo-2'-deoxyuridine (BrdU). After 48 and 96 h of social interaction, subordinate male zebrafish exhibited elevated plasma cortisol concentrations and significantly lower numbers of BrdU+ cells in the dorsal but not ventral regions of the telencephalon compared to dominant or group-housed control male fish. After a two-week recovery in a familiar group of conspecifics, the number of BrdU+ cells that co-labeled with a neuronal marker (NeuN) was modestly reduced in previously subordinate male fish, suggesting that the reduction of cell proliferation during social stress may result in fewer cells recruited into the neuronal population. In contrast to male social hierarchies, subordinate female zebrafish did not experience elevated plasma cortisol, and the numbers of BrdU+ cells in the dorsal telencephalon were comparable among dominant, subordinate, and group-housed control ...

Source: Journal of Experimental Biology - December 10, 2018 Category: Biology Authors: Tea, J., Alderman, S. L., Gilmour, K. M. Tags: RESEARCH ARTICLE Source Type: research