To investigate the relationship between development of traumatic brain edema and changes in posterior hypothalamus excitability, different nuclei of the hypothalamus were excited with electrical stimulation. According to the stimulation method, forty rabbits were randomly divided into the following groups. Group A animals( n =8) were not stimulated and used as the sham control. Group B animals( n =8) underwent stimulation of the posterior nucleus of hypothalamus (PH), Group C ( n =8) stimulation of the dorsal medial nucleus of the hypothalamus (DMH), and Group D ( n =8) stimulation of the ventral medial nucleus of the hypothalamus (VMH). In group E animals( n =8), ? receptor antagonist Regitine was injected intravenously before stimulating PH. During the course of stimulation, intracranial pressure (ICP) was monitored continuously. 3h later, the animals were sacrificed and their cerebral tissue was examined for content of water, K + and Na + . Changes in blood brain barrier (BBB) were traced by a colloidal gold technique. The results showed that stimulation of the three nuclei caused an acute elevation of ICP,which was significantly higher than that before stimulations ( P