[Effect of electroacupuncture at different acupoints on hormones and neurotransmitters of hypotha- lamic-pituitary-adrenal axis in rats under simulated weightlessness].

OBJECTIVE: To explore the change pattern of hypothalamic-pituitary-adrenal (HPA) axis and related neurotransmitters under simulated weightlessness.

METHODS: A total of 40 clean-grade male Wistar rats were randomly divided into a normal group, a tail-suspension group, an electroacupuncture (EA) at Neiguan (PC 6) group, an EA at Sanyinjiao (SP 6) group, 10 rats in each group. Rats in the tail-suspension group, EA at "Neiguan" (PC 6) group and EA at "Sanyinjiao" (SP 6) group were treated with tail suspension to simulate weightlessness effect. Rats in the normal group were treated with normal diet. Rats in the tail-suspension group were treated with tail suspension for 28 d. During the time of tail suspension, rats in the EA at "Neiguan" (PC 6) group were treated with EA at "Neiguan" (PC 6), 30 min per treatment, once every two days for 14 treatments, while rats in the EA at "Sanyinjiao" (SP 6) group were treated with EA at "Sanyinjiao" (SP 6), 30 min per treatment, once every two days for 14 treatments. Samples were all collected after 4 weeks. The contents of corticotropin releasing hormone (CRH) , adrenocorticotropic hormone (ACTH), corticosterone (CORT) in as well as 5-hydroxy tryptamine (5-HT), dopamine (DA), norepinephrine (NE) were measured by using radioimmunoassay.

RESULTS: Compared with the normal group, in the tail-suspension group the content of ACTH in pituitary was significantly decreased (P< 0.05), and the content of 5-HT in hypothalamus was significantly decreased (P < 0.01); the content of CRH and 5-HT in hypothalamus was significantly decreased (P < 0.01, P < 0.05) in the EA at "Neiguan" (PC 6) group; the content of CRH and 5-HT in hypothalamus was significantly decreased (P < 0.01), and the content of CORT in serum was significantly decreased (P < 0.05) in the EA at "Sanyinjiao" (SP 6) group. Compared with the tail-suspension group, the content of ACTH in hypothalamus was significantly decreased (P< 0.05) in the EA at "Neiguan" (PC 6) group; the content of CRH, ACTH and CORT was significantly decreased (P < 0.01, P < 0.05) in the EA at "Sanyinjiao" (SP 6) group. Compared with the EA at "Neiguan" (PC 6) group, the content of CORT was decreased (P < 0.05) in the EA at "Sanyinjiao" (SP 6) group.

CONCLUSION: EA can regulate the content of 5-HT in hypothalamus in tail-suspension rats, inhibit the hyperactivity of the HPA axis, in which EA at "Sanyinjiao" (SP 6) had more significant effects than "Neiguan" (PC 6), but no obvious effects on NE and DA were observed.