Circular connections between intestine and central nervous system

Abstract

1. Electrical stimulation of the peripheral end of the cranial mesenteric intestinal nerve not only modifies the motor activity of the corresponding segment of the jejunum (as is well known), but also evokes or modifies (usually increases) afferent activity in neighboring intestinal nerves and also causes reflex changes in blood pressure, respiration, and action potentials of skeletal muscles in the neck. These afferent effects on distant organs are transmitted along intact intestinal nerves. 2. Preliminary perfusion of the intestinal blood vessels near the recording electrodes with solutions of atropine, ergotamine, or procaine blocks or weakens the afferent activity evoked in the intestinal nerves under normal conditions by stimulation of nearby (15–20 cm) efferent intestinal fibers. 3. A comparative study of various components of the reaction shows that they differ in their latent period. The latent period is shortest for the electrical response of afferent fibers of the intestinal nerves considerably longer for the local intestinal motor response or for reflex changes in arterial pressure and respiration, and longest for the electrical response of the neck muscles. 4. The results described, together with other laboratory observations, indicate that circular mechanisms connecting the organ with the central nervous system may be present in the intestine, just as in other viscera and autonomic ganglia. They are a fragment of more complex chain reactions found in the body.