Hormonal regulation of aquaporins in fishes.

Comparative studies over the last two decades have revealed that fishes leverage aquaporins (AQPs) to facilitate the movements of water, small non-ionic solutes, and gases across cell membranes. Accordingly, AQPs are expressed in tissues responsible for maintaining hydromineral balance of the whole organism. In teleost fishes, threats to hydromineral balance imposed by fluctuations in environmental salinity are met with the activation of multiple endocrine axes. This chapter first discusses recent advances in our understanding of how hormones control the expression of AQPs in tissues that support hydromineral balance, namely the gastrointestinal tract, kidney, and gill. The second objective of this chapter is to review how hormones regulate teleost AQPs in support of fluid transport processes underlying the production of gametes specialized for release into aquatic environments.