Subfornical Organ neurons are CCK responsive

Cholecystokinin (CCK) is a hormone secreted from endocrine cells in the small intestine. The postprandial release of this peptide inhibits the gastric emptying, gastric acid secretion and food intake via the intestinal feedback control, which could be mediated by the activation of neural pathways. At present, the mechanism of CCK‐mediated gut‐brain pathway remains unclear. The subfornical organ (SFO) has been identified as a circumventricular organ (CVO), which lacks the normal blood‐brain barrier. The SFO neurons receive various neural inputs from and send extensive efferent projections to other central nervous system (CNS) sites. Consequently, the SFO has been considered to contain multiple different sensors for sensing neurotransmitters and circulating signaling molecules from blood and cerebrospinal fluid, and subsequently to regulate body fluid balance and the cardiovascular system. Therefore, SFO could be a potential site for CNS actions of circulating CCK to regulate gastrointestinal function. We have used whole cell patch clamp recording combined with dissociated cell technique to examine the effects of CCK on the excitability of SFO neurons. Application of 10 nM CCK depolarized the membrane potential of SFO neurons (8.56± 2.37mV, 14 of 29 cells). Additionally, only two cells were hyperpolarized. Our studies suggest that the potential role of SFO to sense and respond to change in circulating CCK.