Control of Somatostatin Secretion by CCK-1 and CCK-2 Receptors in Rin-14b Cells, a Rat Pancreatic Islet Cell Line

Cholecystokinin and Somatostatin Negatively Affect Growth of the Somatostatin‐RIN‐14B Cells

“…The observation that this inhibition by caerulein was totally reversed by the specific CCK-1 receptor antagonist L-364718 indicates that the CCK-1 receptors are involved in this process of growth inhibition. To eliminate the possibility that somatostatin released in response to caerulein [ 11 ] could be responsible for growth inhibition by the CCK analog, cells were also incubated with an SS antibody along with caerulein; in no time did we observe a difference between growth in the caerulein group alone and caerulein plus the SS antibody (data not shown). As shown in Figure 4 , the SS antibody prevented growth inhibition by SS alone.…”

“…We do not believe that growth of these RIN-14B cells is autoregulated by somatostatin they release into the medium. This conclusion is based on the following observations: (a) these cells grew in a 0.5% inactivated FBS medium when they release into the medium approximately 200 pg mL −1 of somatostatin per 4 hours [ 11 ], and (b) they also grew at their control rates even in the presence of 0.25 μ g mL −1 of a specific somatostatin antibody; an autocrine regulated pathway would have shown these cells grow at a rate above the controls in the presence of the antibody. This was previously observed in vivo when the trophic effect of caerulein on the rat pancreas was significantly enhanced by a simultaneous administration of a somatostatin antiserum, the same used in this study [ 30 ].…”

“…Clones of the original somatostatin cell line were used to study somatostatin secretion (RINT3), intracellular signalling pathways activated in response to CCK receptor subtypes occupation (RIN1027-B2) and CCK receptor subtypes characterization and SS release (RIN-14B) [9–11]. …”

“…In order to have an exclusive and direct access to the pancreatic somatostatin cells and to avoid mixtures of cell types from islet cell cultures, investigators established and cloned a transplantable rat islet cell tumor which secretes insulin and somatostatin [ 8 ]. Clones of the original somatostatin cell line were used to study somatostatin secretion (RINT3), intracellular signalling pathways activated in response to CCK receptor subtypes occupation (RIN1027-B2) and CCK receptor subtypes characterization and SS release (RIN-14B) [ 9 – 11 ].…”