AVP-FRAGMENT PEPTIDES INDUCE CA2+ TRANSIENTS IN CELLS CULTURED FROM RAT CIRCUMVENTRICULAR ORGANS

To investigate receptors for the naturally occurring fragments of [Arg (8)]vasopressin (AVP), Ca2+ measurements were performed in cells cultu red from the subfornical organ (SFO) and the organum vasculosum of the lamina terminalis (OVLT). AVP((4-9)) and AVP((4-8)) applied in nanomo lar concentrations triggered rises in the intracellular Ca2+ concentra tion in neurons and astrocytes cultured from both circumventricular or gans (CVOs) which are located in the lamina terminalis of the rat brai n. The determination of the investigated cell type was confirmed by im munocytochemistry with cell type-specific antibodies. The functional d ata from single cultured cells and receptor autoradiographic studies o n tissue slices favour the existence of specific receptors for AVP fra gments which are different from those for the parental AVP.