Effect of visceral afferent activation on leg extension induced by sciatic afferent stimulation

In cats under light chloralose and sodium pentobarbital anesthesia the effects of electrical stimulation of various visceral afferent nerves on leg extension induced by sciatic afferent stimulation were studied. Stimulation of the central end of the cervical vagus and stellate ganglion produced inhibition of induced leg extension while stimulation of the distal end of the thoracic vagus, coeliac ganglion, and splanchnic nerves produced facilitation. Decortication slightly reduced the inhibitory effect and greatly reduced the facilitatory effect. Additional decerebration greatly reduced the inhibitory effect and almost abolished the facilitatory effect. Spinal transection at C1 completely abolished the inhibitory and facilitatory effects on induced leg extension. These results suggest that visceral afferents facilitate sciatic induced leg extension principally through the cortex while they inhibit extension through the midbrain and hypothalamus.