Electric activity of vagus nerve in rats according to satiety]

Vagus nerve as a part of brain-gut axis transmits peripheral information to the brain via vagovagal reflexes. Electric properties of the vagus are not exactly known. Analysis of electric changes in vagal nerves evoked by physiologic impulse such as stomach distention by food would facilitate applying better documented and therefore safer vagal neuromodulation. The aim of our study was analysis and interpretation of electric properties of the left vagus in vivo in fasted and satiated Wistar rats. Silver measuring electrodes connected to analog amplifier (A-M Systems 3000) were attached to the nerve in the neck region. The signal was filtered and probing by computer recording system (ADInstruments Power Lab) and additional analyses were performed using GNU Octave programme. Our resuts have shown that the higher amplitude the smaller number of counted impulses in the vagus was detected. This relationship was true only till the maximum level typical for each recording (about 15-20 dB). We note that observed inter spike interval can be approximated with log-normal distribution, and that its mu parameter is enough to characterize a particular recording. Satiated rats were characterized by higher number of spikes per second in the nerve than fasted ones (0.9 vs 0.26) indicating that food intake increased nervous activity 3-4 times comparing to fasted state. The outcomes encourage us to state that good quality characteristic of the left vagus nerve activity provides an effective tool for detection of peripheral signals which are transmitting via vagal afferents to the higher centres. Target vagal neuromodulation to obtain certain terapeutic effects may be possible.