Detection of stress and the effects of central nervous system depressants by gastrointestinal smooth muscle electromyography in wakeful rats.

Aims: The altered gut-brain interaction can be in the background of functional gastrointestinal (GI) disorders. In the GI tract, the slow-wave myoelectric signals can be detected by electromyography (EMG). The aims of our study were to follow up the stress induced alteration in the GI tract by smooth muscle EMG in wakeful rats.

Main Methods: The GI tract myoelectric activity of male rats was measured by an electrode pair under the abdominal skin, the responses were detected and analyzed by a software using fast Fourier transformation. Animals were immobilized and treated with either diazepam or haloperidol. The plasma corticosterone level was determined by ELISA kit, the levels of drugs were measured by HPLC, while the direct GI effects of the compounds were tested in an organ bath.

Key Findings: Significant correlation (r = 0.52) was found between the immobilization induced increase in the EMG spectra of the GI tract segments and the increase in corticosterone plasma levels. The stress-reducing effects of diazepam and haloperidol were also detectable by smooth muscle EMG in the GI tract. No direct smooth muscle actions of the drugs were found in organ bath studies.

Significance: The smooth muscle EMG instrument can measure the level of acute stress and is applicable for the investigation of central nervous system affecting drugs through the GI tract in awake rats. This is the first tool to measure the stress response via the GI tract reactions. The technique may open a new perspective in the diagnosis and therapy of psychosomatic disorders.