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AIM: To assess the effect of curcumin in hypothalamic paraventricular nucleus (PVN) and mean arterial pressure so as to explore the central mechanism of hypertension. METHODS: Sixty Sprague-Dawley rats which body weights between 170 and 190 grams fed with a normal salt (0.3% NaCl) or a high salt (8% NaCl) diet for 6 weeks. Meanwhile half of each team received curcumin administration or vehicle by intragastric administration. Mean Arterial pressure was measured noninvasively via tail-cuff instrument and their recording system. The PVN tissue samPles were collected and stored at −80 °C for later analyses. We performed the following experimental procedures: Western blot analysis, immunofluorescence, immunofluorescence and statistical analysis. RESULTS:The average arterial blood Pressure of rats in the high-salt diet group was significantly reduced after 6 weeks of curcumin intervention. The levels of NOX2, NOX4, TLR4, MyD88, IL-6, IL-1β, MCP-1 and ROS in the long-term high-salt diet grouP were significantly higher after curcumin intervention. CONCLUSION:Curcumin can improve blood pressure in hypertensive rats induced by long-term high salt, the mechanism may be related to the imProvement of oxidative stress and inflammatory cytokines in the paraventricular nucleus of the hypothalamus.
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Aim To observe the effect of corticotropin-releasing factor ( CRF) -expressing neurons on presympathetic neurons in hypothalamic paraventricular nucleus ( PVN) of normotensive Wistar Kyoto ( WKY) rats or spontaneously hypertensive rats (SHR) , and to elucidate the underlying neuronal circuit mechanism of central sympathetic hyperexcitability. Methods The expression levels of CRF protein in WKY rats and SHR PVN were determined by Western blot. Meanwhile, the WKY and SHR PVN CRF-expressing neurons and presympathetic neurons were observed by immunofluo-rescent staining. Adult WKY rats and SHR were used in this study. By microinjection of Cre-dependent ade-no-associated viruses ( AAV) that specifically recognized the CRF promoter and AAV of chemogenetics into the PVN, CRF-expressing neurons expressed designer receptors exclusively activated by designer drugs (DREADDs). Human M3 muscarinic DREADD coupled to Gq receptor ( hM3 Dq) was specifically expressed in PVN CRF-expressing neurons in WKY rats, while human M4 muscarinic DREADD coupled to Gi receptor ( hM4Di) was specifically expressed in PVN CRF-expressing neurons in SHR. Clozapine-N-oxide (CNO) , as a designer ligand, would couple to excitatory hM3Dq or inhibitory hM4Di to regulate the excitability of PVN CRF-expressing neurons. Then the PVN presympathetic neurons were retrogradely labeled by microinjection of fluosecent tracer into the intermedio-lateral column (IML) of spinal cord. Lastly, whole cell patch clamp was used to determine the effect of CNO (10 jjumol L~ ) on spontaneous excitatory postsynaptic currents ( sEPSCs) and current-evoked firing of PVN presympathtic neurons of WKY rats and SHR. Results The expression of CRF protein in the PVN of SHR was significantly higher than that of WKY rats, and the activity and number of CRF-expressing neurons in the PVN of SHR were increased. PVN CRF-expressing neurons were expressed with chemogenetic DREADDs and PVN presympathetic neurons were retrogradely labeled with fluorescent tracer in WKY rats and SHR. In SHR expressed with chemogenetic inhibitory hM4Di-mCherry of PVN CRF-expressing neurons, bath application of CNO to the brain slices resulted in a significant decrease in sEPSCs frequency, but no change in their amplitude of labeled PVN presympathetic neurons. In contrast, in WKY rats expressed with excitatory hM3Dq-eGFP of PVN CRF-expressing neurons, CNO had no obvious effect on the sEPSCs frequency and amplitude in PVN presympathetic neurons. Furthermore, bath application of CNO had no significant effect on current-evoked firing of PVN presympathetic neurons of either WKY rats with hM3Dq-eGFP expression in CRF neurons or SHR with hM4Di-mCherry expression in CRF neurons. Conclusions The activity and number of PVN CRF-expressing neurons are increased in SHR, and CRF-expressing neurons enhance the excitability of presympathetic neurons, which acts as a regulatory neuronal microcircuit between CRF neurons and presympathetic neurons in the PVN.
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Aim To explore the effeet of chemogenetic designer reeeptors exclusively activated by designer drugs( DREADD) mediated inhibition of glutamatergic neurons in paraventricular nucleus of hypothalamus (PVN ) on myocardial ischemia-reperfusion injury in mice.Methods Mice were catheterized in PVN by stereotaxic technique, followed by recover}' for three days in individual cages.The mice were then received the inhibitory virus rAAV CaMK E cx-hM4d (Gi)-EG- FP-WPRE-hGHpA or the control vims rAAV CaMK H a - E GF P- W PRE - h GH pA in the PVN nucleus.Three weeks after virus infection, myocardial ischemia-reperfusion injury ( IR) was performed by ligating the left anterior descending coronary artery for 1 h and then releasing it for 2 h.Clozapine N-oxide (CNO) 2 mg •kg 1 was injected intraperitoneally 1 h before IR, to induce inhibition of glutamatergic neurons in PVN by specifically binding to the hM4D receptor ( Gi).TTC staining was used to measure the infarct size, and ELISA was used to measure the serum cTnl concentration.During experiments, the ECG was recorded by PowerLab system.Western blot was used to detect the pro-survival kinase ERK and cleaved caspase-3 proteins in heart tissues, and the expressions of EGFP, CaMKII and c-fos in PVN were examined under fluorescence microscope.Results The glutamatergic neurons in PV N were specifically infected by AAV vectors.When compared with sham group, the ratio of IS/AAR, serum cTnl, c-fos in PVN, and cleaved caspase-3 protein all increased in IR group , but the pERK level decreased.However, hM4D ( Gi) DREADD mediated inhibition of PVN glutamatergic neurons significantly reduced IS/AAR, cTnl concentration and c-fos expression in PVN, as well as the decrease of cleaved caspase-3 and the increase of pERK in heart tissues.Conclusion Chemogenetic DREADD mediated inhibition of glutamatergic neurons in paraventricular nu- cleus of hypothalamus ( PVN) reduces myocardial is- chemia-reperfusion injury in mice.
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Objective@#To investigate the effects of glutamate (Glu) injected into hypothalamic paraventricular nucleus (PVN) on visceral pain of chronic visceral hypersensitivity (CVH) rats and its possible mechanism.@*Methods@#Newborn SD rats were given CVH rat model by colorectal distension (CRD) on the 8th, 10th and 12th day after birth. Thirty rats with successful CVH model were randomly divided into CVH model group (CVH group), CVH + injection of saline into PVN group (NS group), CVH+ injection of Glu into PVN (3, 6, and 12 μg Glu, namely G3, G6, and G12, respectively), 6 rats in each group, and 6 SD rats with matching body mass were taken as sham operation group (Sham group). The pain behavior of the rats was evaluated by pain threshold, abdominal withdrawal reflex (AWR) score, and abdominal external oblique muscle electromyography (EMG). The expression of arginine vasopressin (AVP) and the proliferation of colon tissue were detected by immunohistochemical staining. The apoptosis of colon tissue was detected by TUNEL.@*Results@#Compared with the NS group, the pain thresholds of the G3, G6 and G12 groups increased, and the AWR scores and EMG amplitudes decreased. The differences were statistically significant(Pain threshold: t=7.65, 16.31, 24.78, both P<0.05; AWR scores: t=-2.98, -4.77, -7.29, both P<0.05; EMG amplitudes: t=-3.06, -5.75, -8.92, both P<0.05). Compared with the Sham group, the expression of AVP in PVN of the CVH group and NS group decreased ((42.63±5.20) %, (18.67±2.94) %, (17.53±2.47) %; t=6.95, t=7.56, both P<0.05). The expression of AVP was increased after different doses of Glu into PVN, and the AVP level in G12 group ((18.15±6.49)%) was higher than that of NS group, the difference was statistically significant (t=-4.21, P<0.05). Compared with the Sham group, the expression of PCNA in colonic mucosal cells of the CVH group and NS group decreased ((65.48±1.68) %, (18.39±1.67) %, (17.69±1.68) %; t=34.35, t=34.80, both P<0.05). The expression of PCNA was increased after different doses of Glu injected into PVN, and the PCNA level in G12 group ((59.91±5.63)%) was higher than that of NS group, the difference was statistically significant (t=-12.44, P<0.05). Compared with the Sham group, the expression of apoptotic cells in colonic mucosal cells of the CVH group and NS group increased ((23.38±11.40)%, (83.79±3.57)%, (80.91±2.47)%; t=-8.77, t=-8.54, both P<0.05). The expression of apoptotic cells was decreased after different doses of Glu into PVN, and the G12 group was ((18.15±6.49) %). Compared with NS group, the difference was statistically significant (t=15.65, P<0.05).@*Conclusion@#Injection of Glu into hypothalamic PVN can alleviate the visceral pain behaviors in CVH rats, and its mechanism may be related to arginine vasopressin.
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Objective To investigate the effects of glutamate (Glu) injected into hypothalamic pa-raventricular nucleus (PVN) on visceral pain of chronic visceral hypersensitivity (CVH) rats and its possi-ble mechanism. Methods Newborn SD rats were given CVH rat model by colorectal distension (CRD) on the 8th,10th and 12th day after birth. Thirty rats with successful CVH model were randomly divided into CVH model group (CVH group),CVH + injection of saline into PVN group (NS group),CVH+ injection of Glu into PVN (3,6,and 12 μg Glu,namely G3,G6,and G12,respectively),6 rats in each group,and 6 SD rats with matching body mass were taken as sham operation group (Sham group). The pain behavior of the rats was evaluated by pain threshold,abdominal withdrawal reflex (AWR) score,and abdominal external ob-lique muscle electromyography (EMG). The expression of arginine vasopressin (AVP) and the proliferation of colon tissue were detected by immunohistochemical staining. The apoptosis of colon tissue was detected by TUNEL. Results Compared with the NS group, the pain thresholds of the G3, G6 and G12 groups in-creased,and the AWR scores and EMG amplitudes decreased. The differences were statistically significant (Pain threshold:t=7. 65,16. 31,24. 78,both P<0. 05;AWR scores:t=-2. 98,-4. 77,-7. 29,both P<0. 05;EMG amplitudes:t=-3. 06,-5. 75,-8. 92,both P<0. 05). Compared with the Sham group,the expression of AVP in PVN of the CVH group and NS group decreased ((42. 63±5. 20) %,(18. 67±2. 94) %,(17. 53± 2. 47) %; t=6. 95,t=7. 56,both P<0. 05). The expression of AVP was increased after different doses of Glu into PVN,and the AVP level in G12 group ((18. 15±6. 49)%) was higher than that of NS group,the difference was statistically significant (t=-4. 21,P<0. 05). Compared with the Sham group,the expression of PCNA in colonic mucosal cells of the CVH group and NS group decreased ((65. 48±1. 68) %,(18. 39± 1. 67) %,(17. 69±1. 68) %;t=34. 35,t=34. 80,both P<0. 05). The expression of PCNA was increased after different doses of Glu injected into PVN,and the PCNA level in G12 group ((59. 91±5. 63)%) was higher than that of NS group,the difference was statistically significant (t=-12. 44,P<0. 05). Compared with the Sham group,the expression of apoptotic cells in colonic mucosal cells of the CVH group and NS group increased ((23. 38±11. 40)%,(83. 79± 3. 57)%,(80. 91± 2. 47)%;t=-8. 77,t=-8. 54,both P<0. 05). The expression of apoptotic cells was decreased after different doses of Glu into PVN,and the G12 group was ((18. 15±6. 49) %). Compared with NS group,the difference was statistically significant ( t=15. 65,P<0. 05). Conclusion Injection of Glu into hypothalamic PVN can alleviate the visceral pain be-haviors in CVH rats,and its mechanism may be related to arginine vasopressin.
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OBJECTIVE: To observe the effect of electroacupuncture (EA) stimulation of "Shenmen" (HT 7) - "Tongli" (HT 5) segment of the Heart Meridian on neuronal electrical activities of hypothalamic paraventricular nucleus (PVN) in rats with myocardial ischemia (MI), so as to investigate its possible mechanism underlying improvement of MI. METHODS: Thirty-two SD rats were randomly divided into sham control, model, HT 7-HT 5 and "Taiyuan" (LU 9)- "Lieque" (LU 7) groups (n=8 in each group). EA preconditioning (2 Hz, 1 V, 20 min) was applied to bilateral HT 7-HT 5 and bilateral LU 9-LU 7, respectively, once everyday for 7 days. The electrical activities of the right PVN region were recorded by the implanted microelectrode array(2×4)and Plexon multi-channel acquisition system. Cluster analysis of neuronal signals was carried out by Offline Sorter software. The discharge waveforms, autocorrelation and cross-correlation of neuronal activities were analyzed by using Neuro Explorer software. RESULTS: Cluster analysis of neuronal signals showed that 2, 2, 1 and 1 interneuron in the sham, model, HT 7-HT 5, and LU 9-LU 7 groups, and 3 pyramidal neurons in the HT 7-HT 5 were acquired. Cross correlation analysis showed that the SPK 02 a and SPK 02 b neurons of the HT 7-HT 5 group had an inhibitory relationship. The total discharge frequency was significantly increased in the model group relevant to the sham group (P<0.01), and was markedly lower in the HT 7-HT 5 group than in the model group and LU 9-LU 7 group (P<0.01). Real-time spectrum analysis showed that the local field potential spectrum energy of the HT 7-HT 5 group was significantly lower than that of the model group and the LU 9-LU 7 group. CONCLUSION: EA of HT 7-HT 5 segment of the Heart Meridian can inhibit the electrical activity of interneuron and activate the electrical activity of pyramidal neuron in PVN region, and an inhibitory relationship exists between the interneuron and pyramidal neuron in MI rats, which may be a mechanism of EA in regulating activities of the ischemic heart.
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Objective To evaluate the role of microglia in paraventricular nucleus (PVN) in sus-ceptibility to depression in rats with chronic visceral pain. Methods Ninety-six pathogen-free healthy male Sprague-Dawley rats, aged 8 days, were divided into 6 groups (n= 16 each) using a random number table: sham operation group (S group), chronic visceral pain group (CHVP group), sham operation plus colorectal distension group (S+C group), chronic visceral pain plus colorectal distension group (CHVP+C group), chronic visceral pain plus phosphate buffer solution plus colorectal distension group (CHVP+P+C group) and chronic visceral pain plus minocycline plus colorectal distension group (CHVP+M+C group). Colorectal distension was not performed in S group. In CHVP group, chronic visceral pain was induced by performing colorectal distension twice daily on postnatal days 8, 10, and 12. Phosphate buffer solution 0. 5μl was injected into PVN by stereotaxic method at 8th week after birth in CHVP+P+C group, and 2％ mi-nocycline 0. 5 μl was injected into PVN at 8th week after birth in CHVP+M+C group. Eight rats in each group were selected 2 h later for measurement of visceral pain threshold. In S+C, CHVP+C, CHVP+P+C and CHVP+M+C groups, colorectal distension was performed for 2 times, open field test and sucrose preference test were then performed, the rats were sacrificed and PVN was removed for determination of micro-glial activation by immunofluorescence. Results The pain threshold was significantly decreased in CHVP, CHVP+C, CHVP+P+C and CHVP+M+C groups as compared with S and S+C groups (P<0. 05). The pain threshold was significantly increased in CHVP+M+C group when compared with CHVP +P +C group (P<0. 05). Compared with S, CHVP and S+C groups, the total locomotor distance, the number of rea-ring and sucrose consumption were significantly reduced, and the proportion of activated microglia in PVN was increased in CHVP+C, CHVP+P+C and CHVP+M+C groups (P<0. 05). Compared with CHVP+P+C group, the total locomotor distance, the number of rearing and sucrose consumption were significantly in-creased, and the proportion of activated microglia in PVN was decreased in CHVP+M+C group (P<0. 05). Conclusion Microglia in PVN is involved in regulation of susceptibility to depression in rats with chronic visceral pain.
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El objetivo de la presente investigación fue evaluar el efecto de la estimulación de los receptores CRH2 del núcleo paraventricular hipotalámico sobre la ingesta de alimento y la expresión de la secuencia de saciedad conductual (SSC) en ratas adrenalectomizadas. Se trabajó con ocho grupos independientes de ratas Wistar, cuatro grupos adrenalectomizados (ADX) y cuatro con falsa cirugía. A todos los sujetos se les implantó una cánula en el núcleo paraventricular hipotalámico, y se les administró uno de cuatro tratamientos: vehículo, urocortina 2 (UCN2, agonista de CRH2), antisauvagina 30 (antagonista de CRH2), y antisauvagina-30 + UCN2 (pretratamiento). La administración de UCN2 redujo la ingesta de hidratos de carbono y de grasas en las ratas ADX, debido a la interrupción de la SSC; mientras que en las ratas con falsa cirugía, la UCN2 solo disminuyó la ingesta de grasas, debido al adelanto de la SSC. El pretratamiento previno los efectos inducidos en las ratas ADX, pero no en las ratas con falsa cirugía. Estos resultados indican que los receptores CRH2 modularon la ingesta y la SSC en las ratas ADX, lo que constituye un aporte importante en la comprensión de la etiología de la anorexia y del patrón conductual asociado a esta.
The objective of this research was to evaluate the effect of stimulation of receptors CRH2 in the paraventricular nucleus of the hypothalamus on food intake and expression of behavioral satiety sequence (BSS) in adrenalectomized rats. Eight independent groups of Wistar rats were utilized; four adrenalectomized groups (ADX) and four were false surgery. All subjects were implanted with a cannula in the paraventricular nucleus of the hypothalamus and were administered with one of the four treatments: vehicle, urocortin-2 (UCN2, CRH2 agonist), antisauvagine-30 (CRH2 antagonist) or antisauvagine-30 + UCN2 (pretreatment). UCN2 administration reduced intake of carbohydrates and fats in ADX rats due to the interruption of the BSS. In rats with false surgery it decreased fat intake due to the advancement of the BSS. Pretreatment prevented the effects induced by UCN2 in ADX rats but not in rats with false surgery. These results suggest that receptors CRH2 modulated intake and BSS in ADX rats, contributing with relevant information for the understanding of the anorexic ethiology and the behavioral pattern associated to it.
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ABSTRACT:Hypertension,the first risk factor for stroke and coronary heart disease in the Chinese population, seriously endangers people’s health.At present,China has more than 270 million people with hypertension and an annual increase rate of 1 0 million people.Then how to improve prevention and treatment of hypertension has become an urgent need to solve major medical and social problems.In the past,research on hypertension mainly focused on the peripheral area,while recent research has shown that the central regulation plays an important role in the development of hypertension. Hypothalamic paraventricular nucleus (PVN ), which plays a key role in maintaining cardiovascular activity, can directly control the sympathetic preganglionic neurons and regulate peripheral sympathetic nerve activity,thus being closely related to the development of hypertension.Research in recent years shows that the comprehensive effects of proinflammatory cytokines (PIC ),reactive oxygen species (ROS),renin-angiotensin system (RAS),neurotransmitter (NT)and nuclear factorκB (NF-κB)are involved in the pathogenesis of hypertension.However,it is unclear how these neurohormones in PVN are activated,how they interact with each other and what role they play in the regulatory mechanism of hypertension.Therefore,the key focus of this research is to explore the impact of activated neurohormones in PVN on hypertension.This study will provide new content for the study on hypertension.
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Objective To explore central mechanism of metformin(MET)in salt -sensitive hypertensive rats by assessing the effect of metformin on inflammation and oxidative stress in hypothalamic paraventricular nucleus (PVN),sympathetic nerve activity and blood pressure.Methods Eight -week -old male Dahl salt -sensitive rats were divided into 4 groups:the normal -salt diet control group[0.3% NaCl +intracerebroventricular(ICV)artificial cerebrospinal fluid(aCSF)],the normal -salt diet with MET group(0.3% NaCl +ICV MET 25μg/d],the high -salt diet control group (8% NaCl +ICV aCSF),the high -salt diet with MET group (8% NaCl +ICV MET 25μg/d). Mean arterial pressure(MAP)was determined every week by a tail -cuff occlusion.After 6 weeks,all rats were eutha-nized,and blood and brain tissues were collected.Then,the plasma norepinephrine(NE,an indicator of sympathetic activity)was detected by enzyme linked immune sorbent assay(ELISA).The expression levels of interleukin(IL)-1β,IL -10 and NOX -2[a subunit of NAD(P)H oxidase],superoxide dismutase(SOD)in the PVN were detected by immunofluorescence,immunohistochemistry and Western blot methods.Reactive oxygen species(ROS)was detec-ted by dihydroethidium(DHE)staining.Results The MAP level of high -salt diet with metformin group was attenu-ated compared with that of the high -salt diet control group[(129.55 ±6.52)mmHg vs.(154.47 ±6.57)mmHg, F =121.90,P <0.05].The change of plasma NE level of high -salt diet with metformin group was lower compared with that of the high -salt diet control group[(364.57 ±30.73)pg/mL vs.(547.68 ±25.08)pg/mL,F =179.24, P <0.05].The expression levels of IL -1β,IL -6,NOX -2 and ROS were markedly higher in high -salt diet with metformin than those of the high -salt diet control group(F =27.80,21.20,22.48,31.99,all P <0.05),which of IL -10 and SOD was lower(F =17.69,23.69,all P <0.05).Conclusion Metformin may attenuate blood pressure in salt -sensitive hypertensive rats,at least partly via decreasing inflammatory molecules and inhibiting oxidative stress in the PVN,subsequently inhibiting sympathoexcitation.
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Aim To determine the effects of Qiliqian-gxin injected into lateral ventricle on Cardiac function, angiotensin Ⅱ( Ang Ⅱ) , angiotensin converting en-zyme(ACE), angiotensin type 1 receptor(AT1R) and the sympathetic nervous system in the hypothalamic pa-raventricular nucleus of rats with chronic heart failure. Methods Rat model of heart failure was prepared by acute myocardial infarction that was induced by ligation of the left anterior descending coronary artery. Four weeks after heart failure, Qiliqiangxin and Losartan were continuously administered via a syringe pump in-jector connected to lateral ventricle. After four weeks, echocardiogram was used to evaluate the cardiac func-tion and HE was used to observe myocardial tissue morphology, and enzyme linked immunosorbent assay was used to measure plasma norepinephrine( NE) , ser-um NT-proBNP and Ang Ⅱ in the paraventricular nu-cleus. The expression of ACE and AT1 R at mRNA and protein levels in the paraventricular nucleus was deter-mined by Real-time PCR and Western blot, and the RSNA was measured by PowerLab in anesthetized rats. Results Compared with the sham control, the cardiac function was significantly lower while the AngII, ACE, AT1 R expression in the paraventricular nucleus and RSNA were significantly increased in rats with heart failure. Compared with heart failure control, Qiliqian-gxin and Losartan decreased the RSNA and the AngII, ACE, AT1 R expression in the paraventricular nucleus. Conclusion Giving traditional Chinese medicine to the lateral ventricles can decrease the activation of the RAS system, reduce the renal sympathetic nerve activi-ty and improve cardiac function.
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[ ABSTRACT] AIM:To investigate the transient outward potassium channel protein expression in paraventricular nucleus (PVN) and its contribution to renal sympathetic nerve activity (RSNA) in rats with chronic heart failure (CHF). METHODS:A rat model of CHF was prepared by acute myocardial infarction that was induced by ligation of the left ante -rior descending coronary artery .Four weeks after heart failure , echocardiogram was applied to identify the CHF model and plasma norepinephrine (NE), serum NH2-terminal pro-brain natriuretic peptide (NT-proBNP) were detected by ELISA. The expression of ransient outward potassium channel proteins Kv 4.2 and Kv4.3 at mRNA and protein levels was deter-mined by real-time PCR and Western blot .The mean arterial pressure ( MAP) , heart rate ( HR) and RSNA were measured in anesthetized rats with PVN microinjection of potassium channel blockers 4-AP.RESULTS:In CHF group , the rat car-diac function and Kv4.2 and Kv4.3 expression in PVN were obviously lower while plasma NE and serum NT-proBNP were obviously higher than those in sham group .Microinjection of 4-AP into PVN induced an increase in MAP , HR and RSNA in both sham and CHF rats , while the CHF rats exhibited smaller responses to 4-AP than sham-operated rats .CONCLU-SION:Downregulation of Kv4.2 and Kv4.3 expression in the PVN may be a potential mechanism for sympathoexciation in the rats with chronic heart failure .
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Objective To study the changes of gastrointestinal movement function in rats with chronic unpredictable mild stress(CUMS) and explore the mechanisms underlying it.Methods The rats were divided into stress model group and control group.The stress model rats were induced by 21-day chronic unpredictable mild stress as well as social-isolated fed.The rate of ink propulsion of gastrointestinal tract and the contraction of intestinal canal in rats were observed.Immunohistochemistry was adopted to detect the expression of OT in rats.Results (1) After the models were induced,weight-gain and sucrose preference of model group ((69.97 ± 9.81) g,(49.05± 5.98) g) were lower than those in control group ((116.27 ± 13.60) g,(83.51 ± 3.08) g) (P ＜ 0.001),and both the crossing-score and rearing-score ((24.00 ± 13.52),(3.90 ± 2.51)) were lower than those in control group ((53.60 ± 27.98),(11.50 ± 8.85)) in the open-field test.(2) The rate of ink propulsion of model group ((67.33 ± 6.24) ％) was decreased when compared to the control group ((76.83 ± 10.00) ％) (P ＜ 0.05),and the intestinal canal contraction amplitude and contraction frequency ((1.37 ± 0.18) g,(0.58 ± 0.02) S-1) were lower than those in control group ((1.88 ± 0.13) g),(0.62 ± 0.04) S-1) (P ＜ 0.05).(3) Compared with the control group (6.07 ± 3.71),OT immunoreactive substance was increased in model group (59.17 ± 16.08) of rats (P＜0.001).Conclusion Chronic stress can cause the decrease in gastrointestinal movement function of rats.These changes may be related to the increased expression of OT in paraventricular nucleus.
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Aim To investigate the role of substance P in the brain of asthmatic rats.Methods Rats were injected with aluminum hydroxide and OVA allergens to prepare the animal model of asthma. Then the content of c-fos protein in asthmatic rats' brain was detected by immunohistochemical method (SABC).The content of substance P in paraventricular nucleus (PVN), the content of corticotropin-releasing hormone (CRH) in median eminence (ME), and the content of adrenocorticotropic hormone (ACTH) and corticosterone (CORT) in peripheral blood were detected by radioimmunoassay method. Then exogenous SP, SP receptor antagonist S0145 were microinjected in PVN to observe their effect upon lung function and HPA axis in asthmatic rats. Results In asthmatic rats, the content of SP increased within the PVN. The content of CRH, ACTH and CORT decreased (P<0.05).The ratio of expiratory and inspiratory and airway resistance increased. Diaphragm discharge points and lung compliance decreased (P<0.01).After microinject of SP in PVN, there was a further decrease in pulmonary function and the content of CORT, ACTH and CRH in asthmatic rats (P<0.01).While the SP receptor antagonist S0145 might reverse the change of lung function and hypothalamus-pituitary-adrenal axis (HPA axis) in asthmatic rats.Conclusion In asthmatic rats the SP in PVN can affect the function of HPA axis, involved in asthma attacks.
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Effects of urotensin II (UII) on paraventricular nucleus (PVN) neurons of hypothalamus from brain slices of rats were examined by using extracellular recording technique. The results are as follows: (1) In response to application of UII (0.3, 3.0, 30.0, 300.0 nmol/L, n=39) into the perfusate for 2 min, the spontaneous discharge rates (SDR) of 32/39 (82.05% ) neurons were significantly decreased in a dose-dependent manner; (2) Pretreatment with bicuculline (BIC, 100 μmol/L), a specific GABAA receptor antagonist, led to a marked increase in SDR of 5/7 ( 71.43% ) neurons in an epileptiform pattern. The increased discharges were not significantly changed after UII ( 30.0 nmol/L ) was applied into the perfusate for 2 min; (3) Pretreatment with picrotoxin ( PIC, 50 μmol/L ), a selective blocker of Cl- channel, led to an increase in the SDR of all 12/12 (100%) neurons. The increased discharges were not influenced by the applied UII (30.0 nmol/L) for 2 min in 11/12 (91.67%) neurons; (4) Application of nitric oxide synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 50 μmol/L ) into the perfusate could significantly augment the SDR of 11/12 ( 91.67% ) neurons , while UII ( 30.0 nmol/L ) applied into the perfusate for 2 min led the augmented SDR of all (12/12, 100%) neurons decrease. The results suggest that UII decreases the excitability of PVN neurons of hypothalamus by potentiating GABAA receptor-mediated Cl- current.
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The present study was undertaken to observe the effect of implantation of the anti-cholinergic agents into different brain areas: hypothalamic paraventricular nucleus (PVH), ventral and dorsal hippocampus, thalamus; and to analyse their effect on the neurogenic stress response. The experiment was performed in 60 anesthetized rats with sciatic nerve stimulation. It was found that atropine and hexamethonium implantation into PVH markedly inhibited the adrenocortical response evoked by sciatic stimuli at 30 and 60 min following stimulation. Vehicle implant in the same region was ineffective, suggesting that the action of the agent was specific in the PVR The implantation of atropine into the ventral hippocampus was effective at 30 min following onset of stimulation, and atropine implant in the dorsal hippocampus was ineffective. The above data suggest that atropine and hexamethonium have effect of inhibiting plasma corticosterone level following sciatic stimulation by acting through cholinergic M and N receptors on PVH and nearby neural tissue and that cholinergic M receptors in the ventral hippocampus may be involved in the modulation of stress response.
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Present work was undertaken to investigate the effect of destruction of different non-mediobasal hypothalamic areas on the traumatic stress responses in 64 Sprague-Dawley rats.Leg break was used as a stressor.The plasma corticosterone levels before (Bo) and 20' after the legbreak (Bs) were determined using competitive protein binding assay.The values of Bs/Bo and Bs-Bo were taken as indicators for the magnitude of the stress responses.The animals were divided into 6 groups according to injured brain areas: sham operated group, PVH injured group, PVH partially injured group, PVH minimally injured group, anterior hypothalamic-preoptic area injured group, posterior hypothalamic area injured group.Having compared statistically all Bs/Bo and Bs-Bo values of 6 groups, and on the basis of the fact that in the 4 cases of complete bilateral PVH destruction the stress response could not be entirely abolished, we conclude. (1) In traumatic stress response of conscious animals, PVH plays an important role as compared with other non-mediobasal hypothalamic areas. (2) Some CRF-containing neurons outside the PVH may also participate in the above-mentioned stress response.
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Using electron immunocytochemical method, the ultrastructural distribution and the synaptic connections of CCK-containing neurons in the paraventricular nucleus (PVN) of the rat were studied. The results showed that the CCK-like immunoreactive products located in farge granular vesicles, cytoplasmic matrix, at the periphery of small clear vesicles, rough endoplasmic reticulum and the membrane of mitochondria. The CCK-positive nerve cell bodies were large or small in size and distributed mainly in the medial part of the PVN, subependymal region and the vicinity of capillaries. Some of them as postsynaptic elements formed axosomatic synapses with CCK-negative axonal terminals. The CCK-positive dendrites and axons situated everywhere in the PVN. Some of them as postsynaptic elements formed axodendritic and axoaxonic synapses with CCK-negative structures. Some CCK-positive axonal endings surrounded the capillaries. Other CCK axonal terminals as presynaptic elements formed axosomatic, axondendritic and axo-axonic synapses with CCK-negative structures, respectively. In addition, we have first found that the CCK-positive dendrites penetrated ependyma and contacted directly with the cerebrospinal fluid in third ventricle, the CCK-positive axons traveled in the cavity of third ventricle near the ependyma. The above mentioned results suggested: (1) the soma, dendrite and axon of the CCK-containing neurons and CCK-negetive neurons in the PVN might form local neuronal circuit; (2) the neuron vessel circuit might be established between CCK-containing neurons and the blood vessels in the PVN; (3) the CSFcontacting neurons in the PVN may participate in forming brain-cerebrospinal fluid neurohumoral circuit and regulate functional activity of distal target area through the CSF pathway.
ABSTRACT
The efferent projections of the rostral ventrolateral medulla(RVL) to the hypothalamic paraventricular nucleus(Pa) and the thoracic cord were studied in the adult cat by using WGA-HRP or fluorescent retrograde tract-tracing method. After injection of WGA-HRP or fluorescent tracer Fast blue(FB) into one side of the Pa, retrogradely labelled cells were found in bilateral RVL, with an ipsilateral predominance. The labelled cells decreased in number from the caudal to the rostral level. After injection of FB into one side of the thoracic cord at T_2-T_3 segments, retrogradely labelled cells in the RVL were observed which increased in number from the caudal to the rostral level and reached the peak at 1.0-1.5mm caudal to the trapezoid body. Most of these cells were distributed in the ipsilateral RVL, and clustered in the region 0.0-1.0mm from the ventral surface of the medulla. After Diamino yellow 2HC1 and FB were injected into the Pa and the thoracic cord respectively, only single labelled cells were detected in the RVL, no double labelled cells were found. The above results suggest that the Pa and the thoracic cord receive separate fiber projections from different cells of the RVL.