EFFECT OF CHOLERA TOXIN AND PROSTAGLANDINS ON THE RAT CHOROID-PLEXUS INVITRO

The effects of cholera toxin (CT) and prostaglandins (PG) on choroid plexus cyclic[c]AMP accumulation were measured. Choroid plexuses, isolated from Sprague-Dawley rats, were incubated in Krebs-Ringer bicarbonate buffer containing either CT (10 .mu.g/ml), heat-inactivated CT, PG or appropriate controls. After a minimum incubation period of 60 min with CT, cAMP accumulation (pmol/mg protein) in treated incubates (58.10 .+-. 6.42, n = 6) was 4 times that in controls (14.65 .+-. 1.4, n = 6). This large increase was seen only when theophylline (10 mM) was in the incubation mixture 3-10 min prior to the end of the incubation period. The increase in cAMP accumulation was dose responsive and was irreversible after 5 min of incubation. Of the 5 PG studied, only PGE2 resulted in an increase in cAMP accumulation. cAMP levels were 29.64 .+-. 2.5 in controls and 57.57 .+-. 3.5 in plexuses which were incubated with PGE2 (20 .mu.g/ml) for 1 min, and this increase was dose responsive.