Effects of caerulein-related peptides on cholecystokinin receptor bindings in brain and pancreas

Reduction of food intake by central administration of cholecystokinin octapeptide in the rat is dependent upon inhibition of brain peptidases

“…Jurna & Zetler (1981) also reported a difference in antinociceptive potency of centrally administered caerulein and CCK-8. Both peptides apparently bind to the same receptors with similar affinity (Innis & Snyder, 1980;Van Dijk et al, 1984;Fujimoto et al, 1985) but caerulein has been shown to be more resistant to enzymatic degradation than CCK-8 (Deschodt-Lanckman et al, 1981). In the present study we have seen that after central administration, caerulein is more potent than CCK-8 in reducing food intake both in the absence and in the presence of enzyme inhibitors (compare Figures I and 3).…”

“…Bartho et al (1987) have pointed out that the sensitivity of CCK-receptors found outside the CNS is independent of the type of cells on which they are located. Several investigators (Innis & Snyder, 1980;Van Dijk et al, 1984;Fujimoto et al, 1985) have shown that the affinity of both CCK-8 and caerulein for the peripheral receptor is, if anything, only slightly higher than that for the central receptor. The finding that CCK-8 is active at much lower doses when injected i.p.…”

Cyclic cholecystokinin analogues with high selectivity for central receptors.

“…Moreover, CCK-8 is present in high concentrations in the mammalian brain (6)(7)(8)(9), where it could be a neurotransmitter or neuromodulator, as suggested from various biochemical and pharmacological studies (10)(11)(12)(13)(14)(15)(16). Extensive binding studies have clearly shown that the ligand specificities differ greatly for central and peripheral receptors (17)(18)(19)(20), and irreversible labeling experiments have revealed entities with different molecular weights for pancreas and brain binding sites (21). Nevertheless, the respective roles of both types of receptors in many CCK-8-induced pharmacological responses are still controversial, especially when peripheral or even intracerebroventricular routes of administration have been used (22,23).…”

Haemodynamic and Exocrine Effects of Caerulein at Submaximal and Supramaximal Levels on the Rat Pancreas: Role of Cholecystokinin Receptor Subtypes

“…While CCK 1 receptors are highly discriminating with respect to the presence of a sulphate moiety on the tyrosine residue in the sequence of CCK and peptide analogues including caerulein, CCK 2 receptors bind sulphated and non-sulphated analogues with much less difference in affi nity [26,27] . CCK 1 receptors mediate for example the secretion of pancreatic digestive enzymes and may also be involved in the regulation of satiety and feeding behaviour, while CCK 2 receptors stimulate gastric acid production [28] .…”