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OBJECTIVE@#To investigate the expression and localization of metabotropic glutamate receptors 7 and 8 (mGluR7/8) in rat superior cervical ganglion (SCG) and their changes in response to chronic intermittent hypoxia (CIH).@*METHODS@#We detected the expressions of mGluR7 and mGluR8 in the SCG of 8-week-old male SD rats using immunohistochemistry and characterized their distribution with immunofluorescence staining. The expression of mGluR7 and mGluR8 in the cytoplasm and nucleus was detected using Western blotting. A 6-week CIH rat model was established by exposure to intermittent hypoxia (6% oxygen for 30 s followed by normoxia for 4 min) for 8 h daily, and the changes in systolic blood pressure, diastolic blood pressure and mean arterial pressure were measured. The effect of CIH on expression levels of mGluR7 and mGluR8 in the SCG was analyzed using Western blotting.@*RESULTS@#Positive expressions of mGluR7 and mGluR8 were detected in rat SCG. mGluR7 was distributed in the neurons and small fluorescent (SIF) cells with positive staining in both the cytoplasm and nuclei, but not expressed in satellite glial cells (SGCs), nerve fibers or blood vessels; mGluR8 was localized in the cytoplasm of neurons and SIF cells, but not expressed in SGCs, nerve fibers, or blood vessels. Western blotting of the nuclear and cytoplasmic fractions of rat SCG further confirmed that mGluR7 was expressed in both the cytoplasm and the nucleus, while mGluR8 exists only in the cytoplasm. Exposure to CIH significantly increased systolic blood pressure, diastolic blood pressure and mean arterial pressure of the rats (all P < 0.001) and augmented the protein expressions of mGluR7 and mGluR8 in the SCG (P < 0.05).@*CONCLUSION@#mGluR7 and mGluR8 are present in rat SCG but with different localization patterns. CIH increases blood pressure of rats and enhanced protein expressions of mGluR7 and mGluR8 in rat SCG.
Subject(s)
Male , Animals , Rats , Rats, Sprague-Dawley , Superior Cervical Ganglion , Receptors, Metabotropic Glutamate , HypoxiaABSTRACT
BACKGROUND:The effect of advanced glycation end products (AGEs) on bone resorption is controversial. Our previous study has shown that bone resorption is significantly inhibited when AGEs present with pre-osteoclast cells RAW 264.7, while the effect of AGEs on osteoclastic acidification remains unknown. OBJECTIVE:To investigate the effect of AGEs on osteoclastic acidification and the underlying mechanism. METHODS:RAW 264.7 cells were induced by RANKL (15μg/L;normal group) to generate osteoclasts, and AGEs (50-400 mg/L;experimental group) or bovine serum albumin (100 mg/L;control group) were added at the beginning of the induction. The effect of AGEs on bone resorption was evaIuated by anaIyzing the area of bone resorption on the Osteo Assay Surface plates, and the effect of AGEs on osteoclastic acidification was evaluated by acridine orange staining. Furthermore, the expression levels of V-ATPase a3 and CIC-7 were detected to investigate the underlying mechanism. RESULTS AND CONCLUSION:The bone resorption area in the AGEs group was significantly decreased compared with the normal group (P<0.05). Acridine orange staining reveaIed that the red fluorescence (620 nm) intensity in the AGEs group was significantly decreased compared with the normal group (P<0.05), and this inhibitory effect became obvious with the increase of AGEs concentration. Immunocytochemistry, western blot assay and PCR findings showed that the expression levels of V-ATPase a3 and CIC-7 in the AGEs group were decreased significantly compared with the normal group (P<0.05). To conclude, AGEs exert inhibitory effect on osteoclastic acidification, probably by inhibiting the expression of V-ATPase a3 and CIC-7.
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Aim To investigate the effect of zacopride ( Zac) on cardiac arrhythmia in isoproterenol ( ISO)-in-duced myocardial hypertrophic rats and the underlying electrophysiological mechanisms .Methods ① Fifty-one rats were randomly divided into control group ( n=17 ) , ISO group ( n=17 ) and ISO +Zac group ( n =17 ) .Rat model with cardiac arrhythmia and hypertro-phy was established by intraperitoneal ISO ( 5 mg?kg -1 ) injection.②ECGs were recorded to observe the effects of Zac on arrhythmia in model rats .③ Whole-cell patch clamp was applied to record inwardly rectifi-er potassium current(IK1), resting membrane potential ( RMP ) and amplicated delayed afterdepolarizations (DADs).Results ① Echocardiographic examination showed that , left ventricular end-diastolic dimension (LVEDD) and left ventricular end-systolic dimension (LVESD) significantly decreased in rats in ISO group compared with control group , whereas left ventricular posterior wall end-diastolic thickness ( LVPWd) and in-terventricular septum end-diastolic thickness ( IVSd ) increased ( P<0.05 ) , suggesting rat model of isoprot-erenol-induced myocardial hypertrophy was successfully established .② ECGs showed that 88.89% of rats in ISO group had ventricular premature beats ( VPBs ) , which significantly decreased to 11.11% after the ap-plication of Zac ( P <0.05 ) .③ Values of RMP de-creased from ( -71.05 ±1.27 ) mV in control group to (-69.38 ±1.21 ) mV in ISO group ( P<0.05 ) . After Zac administration , RMP significantly increased to ( -73.86 ±1.33 ) mV compared with control and ISO group(P<0.05).④DADs and TA incidence sig-nificantly decreased from 88.24% in ISO group to 11.76%in ISO+Zac group ( P<0.05 ) .⑤ Compared with control group , IK1 density was markedly reduced in ISO group, whereas Zac could effectively rescue IK1 suppression to normal level .Conclusions Zac, as a selective IK1 channel agonist , can significantly inhibit cardiac arrhythmia in isoproterenol-induced myocardial hypertrophic rats , which is mainly attributed to in-creased RMP by enhancing IK1 and subsequent suppres-sion of DADs.
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BACKGROUND:The effects of advanced glycation end products (AGEs) on osteoclast-induced bone resorption is controversial and the underlying mechanisms remain unclear. Most of the studies indicate that AGEs can enhance bone resorption, while some othersshowthe opposite effects. OBJECTIVE:To investigate the effects of AGEs on osteoclast-induced inorganicmatrixdissolution and organic componentdegradation and the underlying mechanisms. METHODS:RAW 264.7 cels were induced to generate osteoclasts,and AGEs (50-400 μg/mL) or control-bovine serum albumin (100 μg/mL) was added since the beginning of the induction. The effect of AGEs on bone resorption was evaluated by analyzing the area of resorption pits on the Osteo Assay Surface plates and the expression of cathepsin K. Furthermore, the number of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cels, nuclei per osteoclasts and the expression of integrinανβ3were detected. RESULTS AND CONCLUSION:The area of resorption pits and expression of cathepsin K in AGEs groups were significantly decreased compared withthecontrol group, and this inhibiting effect became more obvious with the increase of AGEs concentration. TRAP staining also showed that number of TRAP-positivemultinucleated celsand nuclei per osteoclast were significantly reduced in an AGE dose-dependent manner. Quantitative PCR revealed that the expression of integrin ανβ3decreased significantly with the extension of AGEs incubation time. These data indicate that AGEs can exert inhibitory effects on organic and inorganicmatrixdegradation induced by osteoclasts. The underlying mechanism may be involved in the inhibitory effects of AGEs on directed differentiation and cel fusion of osteoclast precursor cels, and migration and adhension of osteoclasts.
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Aim To investigate the inhibitory effects of zacopride(Zac) on arrhythmia induced by isoproterenol ( ISO) and the underlying mechanisms in rats. Meth-ods ①ECGs were recorded in anesthetized rats in vi-vo to observe the effects of zacopride on arrhythmia in-duced by ISO. ② Intracellular microelectrode tech-nique was used to investigate the effects of zacopride on resting membrane potential, delayed afterdepolariza-tions ( DADs) and triggered activity ( TA) induced by ISO combined with 3. 6 mmol·L-1 CaCl2 in right ven-tricular papillary muscle of rats. Results ① In ISO group rats, ventricular premature beats ( VPB ) oc-curred frequently with ST-segment depression. Com-pared with ISO group, the incidence of VPB in ISO+Zac group decreased from 100% to 50% ( n=6 , P<0. 05 ) and the total number of VPB recorded in 1 hour significantly reduced from 1 574 ± 521 to 33 ± 40 ( n=6,P<0. 05). ② Zacopride at 1 μmol·L-1 could hy-perpolarize the resting membrane potential of right ven-tricular papillary muscle in normal rat from ( -74. 42 ± 1. 95 ) mV to ( -78. 50 ± 2. 07 ) mV ( n =6 , P <0. 05). ③ Zacopride at 1 μmol·L-1 significantly de-pressed the DADs and TA induced by ISO combined with 3. 6 mmol·L-1 CaCl2 in right ventricular papilla-ry muscle. The incidence of DADs decreased from 93. 75% in rats in ISO group to 25% in ISO +Zac group ( n =16 , P <0. 05 ) , and this antiarrhythmic effect could be reversed by 1 μmol·L-1 BaCl2 . Conclusions Zacopride, a selective IK1 channel ago-nist , can significantly inhibit cardiac arrthymia induced by ISO in rats, the mechanism of which is mainly at-tributed to zacopride-induced hyperpolarization of the resting membrane potential and subsequent suppression of DADs and TA via enhancing IK1 . These results pro-vide further evidence that to enhance IK1 moderately may be a feasible pathway for antiarrthymic therapy.