Objective To investigate the mechanisms of astrocytes modulating neurons in rat supraoptic nucleus induced by hypotonic stimulation and the effect of 6-aminomethyl-3-methyl-4H-1，2，4-benzothiadiazine-1,1-dioxide HCl (TAG, a antagonist for taurine) or carbenoxolone (CBX, a gap junction blocker)on the responses of astrocytes and neurons in SON. Methods Adult male SpragueDawley rats were divided into four groups: the control group was injected with 5.5ml/kg 0.9% NaCl solution into the caudal vein; the hypotonic group was injected with 5.5 ml/kg hypo-saline (0.83% glucose plus 0.3% NaCl); TAG + hypotonic and CBX + hypotonic groups were injected with TAG (100μmol/L) or CBX (10g/L) into the lateral ventricle respectively, and were injected 2 hours later with hypotonic saline into the caudal vein. With anti-Fos, anti-vasopressin (VP), anti-glycine receptor (GlyR), anti-glial fibrillary acidic protein (GFAP) and anti-connexin43 (Cx43) immunofluorescent staining methods, the responses of neurons and astrocytes in SON were studied. Results In control rats, Fos-, VP-, and GlyR-expression in the neurons and GFAP- or Cx43-expression in the astrocytes were lower. In hypotonic rats, GFAP-, Cx43- and GlyR signals were more than those in control rats, while Fos- and VP- signals were less. Compared with those in hypotonic rats in TAG + hypotonic or CBX + hypotonic rats, GFAP- and Cx43- signals in the astrocytes were the same, GlyRsignals in the neurons decreased, and Fos- and VP-signals increased. Conclusion Hypotonic stimulation activates SON astrocytes, which then release taurine through gap junction signaling to the neurons