CECOCOLONIC MOTILITY IN THE CHICKEN - EFFECTS OF CHOLECYSTOKININ

The aims of this work were 1) to define electromyographically the moti lity pattern of chicken ceca and colon; 2) to study the changes induce d by photoperiod and food intake on the motility of this area and 3) t o characterize the motor effects of intravenous (i.v.) cholecystokinin in vivo, measuring changes in electrical activity and intracecal pres sure. Electromyographical studies show that in ceca, the spike burst f requency is higher during the day than during the night and in the fed than in the fasted state; about 90% of the bursts propagate towards t he apex and corresponde to filling movements. In the colon the spike b urst frequency during the day is 2.9 bursts/min in animals fed ad libi tum. Nocturnal recordings in animals fed ad libitum and diurnal record ings in fasted animals show a significantly decreased electrical activ ity. Both CCK-8s and CCK4 induce a dose-dependent decrease of colonic electrical activity and a dose-dependent increase in the number of col onic defecations. CCK-4 also causes a slight inhibition in the cecum, whereas CCK-8s induces an increase in cecal electrical activity. Intra cecal pressure recordings performed in anaesthetized animals provide s imilar results. In conclusion, the cecocolonic motility of the chicken displays a circadian pattern and undergoes substantial modifications in the fed compared to the fasted state. CCK-8s is not mediating the i ncreased colonic activity that follows food intake, as its effects on colonic motility are inhibitory. In contrast, i.v. CCK-8s induces defe cation and a dose dependent increase in cecal electrical activity, int raluminal pressure and colonic defecation. Intravenous CCK-4 induces i nhibitory effects both on ceca and colon.