Prolactin controls branchial clcn2c but not atp1a1a.2 in zebrafish Danio rerio.

This study examined the branchial epithelium of stenohaline zebrafish Danio rerio, and in particular Na+ -Cl- cotransporter-like 2 (Slc12a10.2)-expressing ionocytes (Na+ -Cl- cotransporter [Ncc]-cells), which mediate the active uptake of ions from freshwater environments. The study assessed whether the pituitary hormone prolactin (Prl) stimulates the expression of messenger (m)RNAs encoding a Clc Cl- channel family member (clcn2c) and a Na+ -K+ -ATPase α1 subunit (atp1a1a.2) expressed in Ncc-cells. Branchial clcn2c, but not atp1a1a.2 levels, were sensitive to Prl both in vitro and in vivo. These observations suggest that Prl contributes to maintaining systemic Cl- balance via the regulation of clcn2c.