FUNCTIONAL CONSEQUENCES OF CHRONIC IMPLANTATION OF ELECTRODES FOR ELECTROMYOGRAPHIC STUDIES IN THE GASTROINTESTINAL-TRACT OF CHICKENS

The aims of this work were : A) to define the morphological and functi onal changes induced by chronic implantation of electrodes for electro myographic studies and B) to study the evolution of the gastrointestin al myoelectrical activity after electrode implantation. Four lots of a nimals were established : birds implanted with 7 and 5 triplets of ele ctrodes in the gastroduodenal area (lots I5 and I7 respectively); sham operated birds (lot SH) and control (lot C). Body weight was not modi fied by surgery. Food intake, which was transiently decreased, returne d to normal within the first week post-implantation. Gastrointestinal transit time (TT) was significantly increased in lots I7 and SH during the first week. In SH birds TT returned to normal in the second week after surgery, whereas in I7 birds this parameter was not normalized u ntil the third week. Apparent hypertrophy of the duodenum was found in lot I7 but not in lots SH and C (P<0.05). Qualitative electromyograph ical changes were found in lot I7 but not in lot I5, with no morpholog ical changes. The evolution of the electrical signal (frequency and am plitude of spiking) was analyzed in lot I5. Frequency stabilized short ly after surgery (0.8-2 days). In contrast, amplitude increased progre ssively to reach a steady value 9-18 days after surgery. Our results i ndicate that the number of electrodes implanted for electromyographica l studies may induce significant morphological as well as motor change s in the gastrointestinal tract. Thus there should be as few electrode s as possible in order to avoid the changes mentioned above. The patte rn of the electrical signal vaires with time, so that electromyographi cal studies should not be undertaken until a steady level in amplitude and frequency is attained. The control of both factors yields a relia ble electromyogram.