Arginine vasopressin causes morphological changes suggestive of fluid transport in rat choroid plexus epithelium

The experiments described herein use an in vitro preparation of choroid plexus to demonstrate that it is a vasopressin-responsive organ by morphologic criteria. Choroid plexus from rats was incubated for one hour in graded concentrations of arginine vasopressin (AVP). Within physiologic range of molar concentration, incubation in vasopressin induced a decrease in basal and lateral spaces in choroid plexus epithelial cells as well as an increase in number of dark cells. The number of cells with basal spaces decreased significantly from 82.7 +/- 9.2 in control tissue to 19 +/- 18 in tissue incubated in 10(-12) M AVP; similarly, the number with lateral cellular spaces decreased from 20 +/- 8.8 to 7.6 +/- 2.2 cells in 10(-10) M AVP. Dark cells increased in number from 3.8 +/- 2.6 in control conditions to 49 +/- 4 with 10(-9) M vasopressin. These data suggest important effects of arginine vasopressin in cerebrospinal fluid (CSF) on choroid plexus, compatible with enhanced fluid transport across choroid epithelial cells.