Figure 1. Concentration-dependent effect of dopamine (DA), aripiprazole (ARI), and paliperidone (PAL) on prolactin (PRL), growth hormone (GH), and cyclic AMP (cAMP) release and intracellular content in pituitary cells in static cultures.

(a and b) Both ARI and DA inhibited PRL (a) and cAMP (b) release, whereas PAL had no obvious effects on either. Notice that 1 μM ARI was less effective than 1 μM DA in inhibiting PRL and cAMP release. (c) No effect of DA, ARI, or PAL application on GH secretion. (d) A highly significant correlation between cAMP and PRL release in DA-treated cells (open circles) and the lack of significant correlation between these parameters in ARI-treated cells (open squares). (e) No effect of DA, ARI, or PAL on intracellular PRL content. (f) ARI and DA decreased intracellular cAMP content in a concentration dependent manner, whereas PAL increased it at higher concentrations. (g) The lack of a 2 h and 6 h treatment with 1 μM ARI and 1 μM PAL on PRL gene (Prl) expression, shown as relative to the expression of the housekeeping gene Gapdh (100%). (h) A highly significant correlation between intracellular cAMP content vs. released PRL in DA-treated cells and the lack of correlation between these parameters in ARI-treated cells. Correlation analysis shown in panels (d) and (h) was performed as described in the Methods, and data points are derived from panels (a), (b), and (f). *P < 0.01.