A SENSITIVE ASSAY FOR STUDYING DOPAMINERGIC ACTIVITY IN CULTURES OF RAT PITUITARY-CELLS

The dopaminergic and antidopaminergic activity of drugs is frequently assayed in pituitary cell cultures. Here we describe a modified versio n of the assay based on the use of pituitary cells from prepubertal fe male rats. Under our experimental conditions (50 000 cells well(-1), 2 -day culture and 2-h drug-exposure) the assay yielded high selectivity and sensitivity for drug dopaminergic activity. D-2 agonistic activit y of bromocriptine could be observed at a concentration as low as 10(- 15) M, the antagonistic activity of haloperidol at 10(-16) M. The assa y also proved reproducible and simple enough for routine screening of dopaminergic activity. The assay enabled dopaminergic agonist and anta gonist activity to be revealed at very low drug concentrations. The hi gh sensitivity of the assay could be of advantage in studying dopamine rgic activity in samples containing active substances present at low c oncentrations or for disclosing the activity of substances with low do paminergic potency.