Résumé
OBJECTIVE: To explore the effect of γ-aminobutyric acid (GABA)ergic neuronal circuit of the central amygdaloid nucleus (CeA) and the paraventricular nucleus of hypothalamus (PVN) on electroacupuncture (EA)-induced regulation of gastric function by way of CeA-PVN projection. METHODS: The present study included 3 parts: 1) C57BL/6 mice were randomly divided into control and EA groups (n=6 in each group). EA was applied to right "Weishu"(BL21, Back-shu point) and "Zhongwan"(CV12, Front-mu point) for 20 min, followed by detecting the expression of c-fos in the CeA and PVN by using immunofluorescence staining; 2) Microinjection of anterograde tracer (rAAV-EF1α-DIO-mcherry-WPRE-pA) into the CeA was conducted in GAD2-Cre mice for confirming the projection of GABAergic neurons from CeA to PVN; 3) GAD2-Cre mice were randomly divided into rAAV-DIO-mcherry (intra-CeA injection of rAAV-EF1α-DIO-mcherry-WPRE-pA), rAAV-DIO-hM3D（Gq）-mcherry(intra-CeA injection of rAAV-EF1α-DIO-hM3D(Gq)-mcherry-WPRE-pA) and rAAV-DIO-hM3D（Gq）-mcherry+EA groups(n=6 in each group). The food intake and gastric empty were detected, and the concentration of GABA in the PVN was assayed by using high performance liquid chromatography on the 28th day after intra-CeA injection. RESULTS: 1) The expression of c-fos in the CeA and PVN was significantly increased in the EA group relevant to the control group(P<0.01), suggesting an activation of neurons in both CeA and PVN after EA. 2) Following CeA injection of rAAV-EF1α-DIO-mcherry-WPRE-pA, the densely expressed virus GABAergic neurons were found in CeA and large number of projection fibers found in the PVN, suggesting a direct connection between CeA and PVN. 3) After activating the GABAergic neurons of CeA, the concentration of GABA in the PVN was obviously increased (P<0.01), the food intake and the gastric empty were considerably decreased relevant to the rAAV-DIO-mcherry group(P<0.01). Following EA intervention，the concentration of GABA in the PVN was obviously decreased(P<0.01), the food intake and the gastric empty were significantly increased relevant to the rAAV-DIO-hM3D（Gq）-mcherry group (P<0.01). CONCLUSION: EA of BL21 and CV12 (Back-shu and Front-mu acupoints) can increase food intake and gastric empty in GAD2-Cre mice, which may be achieved by suppressing the release of GABA in PVN through CeA-PVN GABAergic neural circuit.
Résumé
OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.
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AIM:To observe the effect of central prostaglandin E2(PGE2) on sympathetic activation in chronic heart failure (CHF) and to explore the underlying mechanism. METHODS:Male SD rats were subjected to coronary ar-tery ligation to induce heart failure (HF), and the intracerebroventricular infusion was performed by osmotic pump continu-ously. The rats in sham group and HF group were given artificial cerebrospinal fluid (0. 25 μL/h). The rats in HF plus treatment group was given celecoxib (CLB; 20 mg/h). After 4 weeks, the levels of PGE2 in cerebrospinal fluid ( CSF), the sympathetic nerve excitability and cardiac function were measured, and the changes of corticotropin-hormone releasing hormone ( CRH)-containing neurons activation and neurotransmitter contents in the hypothalamic paraventricular nucleus ( PVN) were also determined. RESULTS:Compared with the sham-operated rats, the HF rats had raised level of PGE2 in CSF, up-regulated renal sympathetic nerve activity and plasma norepinephrine, increased left ventricular end diastolic pres-sure, lung-to-body weight and right ventricular-to-body weight ratios, and decreased maximal increase and decreased rate of left ventricular pressure (P<0.05). In addition, the number of CRH positive neurons in PVN and the level of plasma ad-renocorticotropic hormone were higher in HF rats than those in sham-operated rats (P<0.05). After administration of CLB into the lateral ventricle of HF rats, the contents of PGE2 in CSF were significantly reduced, the number of activation CRH neurons in PVN was decreased, the excitability of sympathetic nerves was down-regulated and cardiac function was im-proved (P<0.05). Compared with the sham-operated rats, the content of glutamic acid in PVN of HF rats was increased, the content of γ-aminobutyric acid and the number of glutamate decarboxylase 67-positive neurons were decreased ( P<0.05). After the CLB was given, the above indexes were reversed (P<0.05). CONCLUSION:These findings indicate that in CHF, the increased central PGE2 may activate CRH-containing PVN neurons and contribute to the augmented sym-pathetic drive possibly by modulating the neurotransmitters within the PVN.
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Aim To investigate the role and mecha-nism of exchange protein directly activated by cAMP (Epac) protein in the paraventricular nucleus(PVN) of the hypothalamus in the development of inflammatory pain in rats. Methods Adult SD male rats were cho-sen to establish the model of inflammatory pain through subcutaneous injection of complete Freund's adjuvant(CFA) on the center of left hind foot. Western blot was used to detect the changes of the expression of Ep-ac protein. Thermal withdrawal latency(TWL) was ob-served after the PVN injecting 8p-CPT-2′-O-Me-cAMP (8p-CPT),the agonist of Epac. Then activated down-stream MEK1/2 protein of Epac in PVN was detected using Western blot when the potency was the strongest.Results ① Compared with normal saline(control group),TWL decreased significantly on d 1, d 3, d 5, d 7,d 9 on the ipsilateral foot of CFA group rats(P<0.01),whereas it returned to normal level in d 13;the paw mechanical withdrawal threshold(PMWT) de-creased significantly on d 6,d 8,d 10,d 12 and d 14 (P<0.05);②Compared with the control,the Epac1 protein in CFA group rats began to decrease from d 3, and significantly decreased on d 3 and d 9(P<0.05), however the expression of Epac2 had no significant change, meanwhile p-MEK1/2 protein decreased sig-nificantly on d 3(P<0.05);③Compared with micro-injection of saline into the PVN(Saline group), the heat hyperalgesia of 20 min and 1h decreased signifi-cantly and TWL increased significantly after PVN ad-ministration of 8p-CPT(8p-CPT group)(P <0.05);paraventricular nucleus p-MEK1/2 protein expression increased significantly in 30 min(P <0.05) and re-covered to normal level 2 h after administration. Con-clusion The Epac1-MEK1/2 signaling pathway in the paraventricular nucleus of the hypothalamus may be in-volved in the development of chronic inflammatory pain induced by CFA.
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AIM: To observe the expression of corticotropin releasing hormone (CRH) within the paraventricular nucleus of hypothalamus (PVN) and to explore the relationship between the activated CRH-containing neurons and sympathetic activity in rats with heart failure (HF).METHODS: Healthy male Sprague-Dawley (SD) rats were subjected to coronary artery ligation to induce HF, and chronic intracerebroventricular (ICV) infusion was performed by osmotic pump for 4 weeks.The rats in sham group and HF group were given vehicle (VEH;artificial cerebrospinal fluid 0.25 μL/h).The rats in HF plus treatment group were treated with CRH competitive inhibitor αh-CRH (15 mg/h).Meanwhile, the Lewis rats and Fischer 344 rats for control study also underwent coronary ligation to induce HF or sham surgery.After 4 weeks, left ventricular end-diastolic pressure (LVEDP) and maximum positive/negative change in pressure over time (±dp/dtmax) were determined.The right ventricular-to-body weight (RV/BW) and lung-to-body weight (lung/BW) ratios were calculated.The renal sympathetic nerve activity (RSNA) was recorded and the plasma norepinephrine (NE) level was measured.The expression of CRH in the PVN combined with the plasma adrenocorticotrophic hormone (ACTH) levels were measured.RESULTS: Compared with the sham-SD rats, the HF-SD rats had a greater number of CRH positive neurons in the PVN (accordingly the plasma ACTH levels were increased), accompanied by decreased ±dp/dtmax and increased RSNA, plasma NE, LVEDP, lung/BW and RV/BW.However, ICV treatment with αh-CRH attenuated these changes in the HF-SD rats (P<0.05).Compared with the sham-Fisher 344 rats, the HF-Fisher 344 rats also had a greater number of CRH positive neurons in the PVN (accordingly the plasma ACTH levels were increased).In addition, they had significantly increased RSNA and plasma NE level, higher LVEDP, RV/BW and lung/BW, and lower ±dp/dtmax (P<0.05).Compared with the SHAM-Lewis rats, the HF-Lewis rats had not significantly changed in the above parameters.CONCLUSION: In CHF, the CRH-containing neurons in PVN are activated, thus aggravating cardiac function by increasing sympathoexcitation.
Résumé
Methods including stimulation, cauterization, of nuclei and measurement of pain threshold were used to clarify the role of paraventricular nucleus of hypothalamus (PVH) in pain regulation. Results showed that electrical or L-glutamate sodium stimulation of PVH could elevate the pain threshold in the rat dose-dependently, electrical cauterization of PVH could reduce the pain threshold; and removal of the pituitary gland could not influence the effect of L-glutamate sodium on pain threshold. These results suggest that PVH may play an important role in pain regulation.