BACKGROUND: Most of the studies about the regulation effect of substance P(SP)on reproductive axis involve female and few are about male.The effect of SP on the regulation of hypothalamus-pituitary-testes axis is unclear.OBJECTIVE: To observe the effect of SP on gonadotropin-releasing hormone (GnRH),luteinzing hormone (LH)and testosterone(T) in hypothalamus-adenohypophysis-testes cells.DESIGN: Controlled observation.SETTING: Department of Physiology and Deparment of Nuclear Liaoning Medical University.MATERIALS: Ten healthy male SD rats,of common grade,weighing from 230 to 250 g,were provided by the Experimental Animal Center of Liaoning Medical University.SP(Sigma,USA);LH and T radioimmunoassay kit (Nuclear Medical Technology Center of Tianjin Radiology Medical College);γ-immunology counter(state-run 262 Plant);all-purpose refrigerated centrifuge(DLL-4A,Dachang Medical Instrument Factory,Jiangsu).METHODS:This experiment was carried out in the Department of Physiology and Department of Nuclear Medicine,Liaoning Medical College in January 1997.The SD rats were raised at room temperature.One week later,hypothalamus tissue and adenohypophysis were separated.Abdominal cavity was cut open to take out bilateral testicles.The tegument was removed.The 3 kinds of tissues were cultured by cell culture technology separately. The cells of hypothalamus-adenohypophysis-testes were perflused with100 mg/L SP as follows:hypothalamus-adenohypophysis (the first group);hypothalamus (sp)-adenohypophysis (the second group);hypothalamus-adenohypophysis (sp) (the third group); adenohypophysis-testes (the fourth group);adenohypophysis-testes (sp)(the fifth group).The content of LH in adenopituicyte culture fluid and T in testes culture fluid were measured with radioimmunoassay.MAIN OUTCOME MEASURES:SP was perfused into the culture fluid of hypothalamus-adenohypophysis,then the content of LH in the adenopituicyte culture fluid and T in the testes culture fluid were measured.RESULTS:All the experimental animals were involved in the result analysis.①The content of LH in the adenopituicyte culture fluid of the second group was significantly higher than that of the first group(t=2.6116.P＜0.01).②There was no significant difference in the content of LH in the adenopituicyte culture fluid between the third group and the first group(t=0.8846,P＞0.05).③The content of T in the testes culture fluid of the fifth group was significantly lower than that of the fourth group(t=3.1618,P＜0.01).CONCLUSION:①SP at hypothalamus level can promote the secretion of GnRH,thus,the secretion of LH in the adenohypophysis culture fluid can be promoted.②SP at adenohypophysis level has no influences on the secretion of LH.③SP at testes level has direct inhibitory effect.