CCK (27-33) is a C-terminal fragment of CCK , a peptide hormone found in the intestine and brain that stimulates digestion, mediates satiety, and is involved in anxiety. Non-sulfated CCK (27-33) inhibits binding of [3H]naloxone in rat cerebellum membranes (IC50 = 4 uM) and inhibits electrically-stimulated contraction of isolated guinea pig ileum (IC50 = 17 uM), an effect that can be reversed by naloxone. Unlike sulfated CCK (27-33), the non-sulfated form does not reduce exploratory behavior in mice when administered at doses up to 1 uMol/kg.
References:
[1]. Raybould, H.E., and Lloyd, K.C. Integration of postprandial function in the proximal gastrointestinal tract. Role of CCK and sensory pathways Ann. N.Y. Acad. Sci. 713(1), 143-156 (1994).
[2]. Ondetti, M.A., Plu??ec, J., Sabo, E.F., et al. Synthesis of cholecystokinin-pancreozymin. I. The C-terminal dodecapeptide J. Am. Chem. Soc. 92(1), 195-199 (1970).
[3]. Schiller, P.W., Lipton, A., Horrobin, D.F., et al. Unsulfated C-terminal 7-peptide of cholecystokinin: A new ligand of the opiate receptor Biochem. Biophys. Res. Commun. 85(4), 1332-1338 (1978).
[4]. Crawley, J.N., St-Pierre, S., and Gaudreau, P. Analysis of the behavioral activity of C- and N-terminal fragments of cholecystokinin octapeptide J. Pharmacol. Exp. Ther. 230(2), 438-444 (1984).