The abdominal cutaneous reflex circuit in the rat: a spinobulbo-spinal reflex in phenobarbital-anesthetized animals

A description is given of an abdominal reflex (ACR) in the rat evoked by cutaneous stimulation. Latency of the ACR in response to stimulation of the contralateral hindlimb was 28.5 +/- 3.2 msec. Data from the analysis of discharges in dorsal and ventral roots and from bulbar reticular neurons triggered by ACR stimuli reveal that a spino-bulbo-spinal loop seems to be implicated. This is also supported by the chronic effects of pontile and spinal transections. ACR-concomitant discharges were also recorded in other axial (digastric m. and internal intercostal m.) and proximal limb muscles. The possible spino-bulbo-spinal mechanism of this cutaneous reflex is discussed.