Biogenic amines serotonin and dopamine regulate cholangiocyte hyperplastic and neoplastic growth

Figure 1 Schematic representation of the mechanism of the serotonin-induced decrease in cholangiocyte proliferation. Activation of 5-HT 1A/1B receptors results in an increase in IP₃/Ca²⁺/PKC pathway, which in turn decreases the adenylyl cyclase/cAMP/PKA/ERK1/2 pathway. This ultimately leads to a decrease in cholangiocyte proliferation. (This figure was adapted from DeMorrow et al[3] and reproduced with permission from the Society for Experimental Biology and Medicine).

Figure 2 Schematic representation of the mechanism of the dopamine-induced decrease in ductal secretion. Activation of D2DR results in an increase in IP₃/Ca²⁺/PKC pathway, which in turn decreases the ductal secretion.