The gastric vagus supplies critical information to the brain for the control of feeding and aversive signaling, such as nausea and vomiting. This perfusion chamber model (with a grid for testing mechanical stimuli) is designed to test mechanical or chemical stimuli applied to the stomach while recording electrophysiological responses from the vagus, from teased fiber bundles or the whole nerve. The dissected stomach, with attached vagus, of small laboratory animals, including musk shrew (a vomiting species) and mouse (a non-vomiting species), can be placed in the perfusion (stomach) compartment and kept alive with oxygenated Krebs solution flowing through the input port and exiting through the two outflow ports (2 are used to ensure that the compartment will not overflow). The included detachable grid allows the experimenter to record the placement of a mechanical probe in alphanumeric coordinates; Von Frey filaments (e.g., 10 mg force) can to used to apply mechanical stimulation. The recording compartment contains holes for placement of fine wire electrodes, which can be guided to the top of the model for connections to recording equipment (e.g., high impedance head stage and amplifier system). The two compartments are sealed by running the nerve connected to the stomach under a plastic gate, coated with vacuum grease; the gate is lowered into grooves that are part of the model.

Based on this model, it is possible to produce a testing chamber for a larger species, such as the laboratory rat, by extending the size of the stomach compartment.

This project received funding support from the NIH SPARC Program, Award number = U18EB021772.