To observe the effect of electroacupuncture(EA) at "Shenmen"(HT7) and "Sanyinjiao"(SP6)on energy metabolism in paraventricular nucleus (PVN) of hypothalamus in insomnia rats, so as to explore its mechanism underlying improvement of insomnia.
A total of 66 SD rats (half male and half female) were randomized into 3 groups：normal control, model and EA groups(n＝22 per group). The insomnia model was established by binding the rat for at least 4 h (step increase of 30 min per day), once daily for 15 days. EA (5 Hz /25 Hz, 0.5－1.0 mA) was applied to unilateral HT7 and SP6 for 15 min, once daily for 5 days. The rats' spontaneous activities during day and night were recorded by using the ClockLab Data Collection and Analysis System, and the duration of exhausted swimming was detected by using load-bearing endurance swimming test. The expression of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) of PVN tissue was assayed by Western blot, and the contents of acetyl coenzyme A (Ac-CoA) and Na＋-K＋adenosine triphosphatase (Na＋-K＋-ATPase) in the PVN tissue, and corticosterone (CORT) in plasma were assayed by ELISA. Changes of the ultrastructure of PVN cells were observed by transmission electron microscope.
After modeling, the rats' daytime and nocturnal locomotor activities were significantly increased and decreased, respectively (P<0.05), and the duration of exhausted swimming was considerably shortened in the model group compared with that of the normal control group (P<0.05). The expression level of AMPK protein in the PVN was obviously up-regulated (P<0.05), and the contents of Ac-CoA and Na＋-K＋-ATPase in PVN and CORT in plasma were markedly decreased in the model control group relevant to the normal group (P<0.05). After EA intervention, the increased daytime locomotion and the decreased nocturnal activities, the shortened duration of exhausted swimming, the up-regulated expression of AMPK, and the decreased Ac-CoA, Na＋-K＋-ATPase and CORT contents were all reversed in the EA treated rats relevant to those of the insomnia rats (all P<0.05). Moreover, ultrastructural observation showed mitochondrial swelling and disappearance of partial ribosomes in the plasma of PVN cells in the model group, while in the EA group, only mild swelling of some mitochondria was found, being with basically normal nuclear membrane, mitochondria, rough endoplasmic reticulum, Golgi complex and ribosomes.
EA at HT7 and SP6 has a positive effect in improving insomnia and insomnia-induced fatigue in insomnia rats, which may be associated with its effects in restraining the expression of AMPK protein, and up-regulating the contents of Ac-CoA and Na＋-K＋-ATPase in PVN and CORT in plasma.