Objective To explore the neuroanatomical basis of acupoint-visceral correlation by studying the distribution of the neurons associated with acupoint"Shenshu"(BL 23)area and adrenal gland in rats.Methods AF 488-CTB and AF 594-CTB were injected into the left side of BL 23 area and adrenal gland in the same rat respectively.Three days after injection

the dorsal root ganglions(DRG)

sympathetic chain

and spinal cord were dissected out from the perfused rats.The neuronal labeling with AF 488/594-CTB was directly observed on the sections under a fluorescent microscope or a laser scanning confocal microscope.Results All neural labeling was observed in the injection side.The sensory neurons associated with both acupoint BL 23 and adrenal gland distributed from thoracic(T)10 to lumbar(L)2 DRG with high concentration in T 12-T 13 and T 11-T 12

respectively

in which some of them were simultaneously labeled with both AF 488/594-CTB and located in T 12-L 1 DRG.For the sympathetic innervation

the postganglionic neurons correlated with BL 23 and adrenal gland were labeled with AF 488/594-CTB separately in the sympathetic chain at the lumbar segments

while the labeled preganglionic neurons were only observed at the lateral horn of T 11-T 13 spinal segments in the cases of adrenal gland.In addition

the labeled motor neurons were mainly detected in the spinal ventral horn at cervical(C)7-C 8 and T 11-L 1 segments.Conclusion These results indicate that there are segmental correlation between BL 23 and adrenal gland on the sensory and sympathetic innervations

and this correlation might be a neural pathway for modulating the function role of adrenal gland through BL 23 needling.