Androgen effects on immune gene expression during parental care in bluegill sunfish (Lepomis macrochirus)

Reproductive efforts are energetically costly and often result in significant trade-offs with other metabolic processes. In many animals, androgens influence how this energy is allocated during the breeding period. In this study, androgen levels of parental bluegill sunfish (Lepomis macrochirus Rafinesque, 1819) were manipulated by implanting males with either 11-ketotestosterone (11-KT) or flutamide (an androgen receptor antagonist) shortly after spawning. Parental behaviours were assessed for 3 days after implantation. Differential brain gene expression between the two groups was examined using a 44 000 microarray gene chip. We found that 11-KT-implanted males exhibited lower levels of expression of genes related to immune function compared with flutamide-implanted males, suggesting that high androgen levels negatively affect the male immune system. These data thus indicate that a significant trade-off may exist between maintaining high levels of androgens and decreased immune function in parental male bluegill.