The functional linkage among the "ZSL"-spinal dorsal horn-SN.
Electrical stimulation of the Zusanli point (ZSL) and solitary tract nucleus (SN) as well as microelectrode recording from the laminae III-V of the lumbar spinal dorsal horn have been used on the pentobarbital anesthetized rats, finding and identifying 57 spinal neurons responding to the stimulations of both ZSL and SN. Among them, 34 responded antidromically to SN; the others responded orthodromically to SN. Among them, the low-threshold mechano-receptive (LTM) neurons and wide-dynamic-range (WDR) neurons were 50 percent respectively. The results indicate that (i) a single spinal dorsal horn neuron receives somatic afferent input and then conveys it to the visceral sensory nucleus-SN; (ii) some spinal dorsal horn neurons receive, in turn, innervation from the SN; (iii) the convergence and integration between somatic and visceral sensory inputs might occur in the spinal dorsal horn neurons and/or SN.