Role of Brain Angiotensin-II in Development of Experimental Diabetic Nephropathy in Wistar Rats

Abstract The renin-angiotensin-aldosterone system (RAAS) plays a key role in diabetic nephropathy (DN). Angiotensin-II secreted during the RAAS pathway increases nephropathy. It stimulates oxidative stress which can quench nitric oxide. Reduced nitric oxide level aggravates Ang-II-induced vasoconstriction. Ang-II has also emerged as a central mediator of the glomerular hemodynamic changes that are associated with renal injury. Deletion of ACE2 is also noted due to increased Ang-II level which leads to the development of DN. We hypothesize that nephropathy caused by Ang-II in the periphery may be controlled by brain RAAS. ACE inhibitors and ARBs may show the renoprotective effect when administered through ICV without crossing the blood-brain barrier. DN was observed after 8 weeks of diabetes induction through alloxan. Administration of captopril and valsartan once and in combined therapy for 2 weeks, significantly reduced urine output, blood urea nitrogen, total protein in the urine, serum cholesterol, serum creatinine, serum triglycerides, and kidney/body weight ratio as compared to diabetic control rats. Further, combination therapy significantly increased the body weight and serum nitrate level as compared to diabetic control animals. However, increased ACE2 levels in the brain may reduce the sympathetic outflow and might have decreased the peripheral activity of Ang-II which shows beneficial effects in DN.

Evaluating the olfactory dysfunction and cognitive deficits induced by intracerebroventricular injection of Amyloid beta (1–42) in female C57BL/6 mice

Amyloid-β (Aβ) is a key pathological hallmark of Alzheimer's disease (AD), the most common form of dementiamajorly occurring in the geriatrics. Aβ accumulation is observed in the brains of AD patients and is reported toproduce long-term effects on cognitive functions leading to neurodegeneration, and subsequently, to AD. Olfactorydeficits are reported in AD and are proposed to be another consequence of these accumulations. The present studywas performed to primarily investigate the olfactory behavior and neurochemical changes in olfactory bulb uponintracerebroventricular (i.c.v) injection of Aβ (1–42) in female C57BL/6 mice. The study also assessed the cognitivechanges of i.c.v injected animals and recorded the subsequent changes in their hippocampus. All behavioral andneurochemical variations were noted separately on 7th, 17th, and 28th day after i.c.v injection. Results from thebehavioral analysis indicated prominent olfactory deficit from the 7th day. Reactive oxygen species levels increasedin both the tissues after Aβ injection. Neurotransmitter data showed that pathological accumulation of Aβ increasesglutamate levels in bulb and hippocampus. Additionally, histopathological evidence supported the neurochemical data.Data from the present study confirmed an olfactory dysfunction associated with AD and reported the neurochemicalchanges leading to these deficits in a non-transgenic model.

Effects of intracerebroventricular injection of 7-nitroindazole on depression-like behaviors and nNOS expression in hippocampal of rats / 中华行为医学与脑科学杂志

Objective To evaluate the effect of intracerebroventricular injection of 7-nitroindazole (7-NI) on the depression-like behaviors in normal rats.Methods According to body weights,48 SD rats were randomly divided into normal group,model group,sham-operation group and 7-NI groups at different concentrations (n=8).The model group was treated with chronic and unpredictable mild stress.The 7-NI groups received intracerebroventricular injection with 7-NI solutions at different concentrations,once every 3 days for 3 times in total.The sham-operation group was injected with DMSO of the same volume.The rat behaviors were then subjected to the open field test (OFT).The hippocampal nNOS protein levels were detected by Western blot.Results Compared with the normal group((132.47±31.72) m),the total movement distances of model group ((15.04±8.61) m) and 200 nmol/0.5 μl surgery group((18.18± 11.82) m) decreased significantly (P＜ 0.05).Compared with the model group,such distances of sham-operation group ((107.33±20.35)m) and 7-NI groups(50 nmol/0.5 μl:(138.40±56.85)m,(86.97±36.20)m);100 nmol/0.5 μl:(86.97±36.20)m) increased significantly (P＜ 0.05).The normal group entered the central area significantly more times(2.25±2.05) than model group (0.25±0.46)and 200nmol/0.5μl 7-NI group (0.25± 0.46) did (P＜0.05),and the number of times entering the central area of the model group (0.25±0.46)was significantly lower than that of the sham-operation group (1.00 ± 1.07,P＜ 0.05) and 50 nmol/0.5 μl group (0.75 ± 1.16).Compared with the normal group ((46.53 ±41.16) s),the durations of stay in the central area of model group ((1.27 ± 1.92) s) and 200 nmol/0.5 μl 7-NI group ((1.53 ± 2.90) s) were shortened significantly (P＜0.05).Compared with the model group,the durations of stay in the central area of 100 nmol/0.5μl group ((36.54±67.80) s) was lengthened significantly (P＜ 0.05).Western blotting showed that the hippocampal nNOS protein levels of model group (0.43±0.11) and 200 nmol/0.5μl 7-NI group(0.56±0.08) significantly exceeded that of the normal group (0.04±0.02,P＜0.05).The levels of nNOS in sham-operation group (0.04 ±0.02) and 50 nmol/0.5 μl 7-NI group (0.22± 0.08),which were significantly lower than that of the model group (0.43 ± 0.11,P＜ 0.05),were similar to that of the normal group (0.04 ± 0.02,P＞ 0.05).Conclusion Intracerebroventricular injection 200 nmol/0.5 μl 7-NI solution results in depression-like behaviors and increased the expression of nNOS protein reflexively in rats.

Effect of Intracerebroventricular Injection of Neuropeptide S on Pain and Anxiety Behaviors in Rats with Neuropathic Pain / 中国康复理论与实践

@#Objective To investigate the effects of intracerebroventricular injection of neuropeptide S (NPS) on pain and anxiety behaviors in rats with neuropathic pain, and explore the possible mechanism. Methods 40 male Sprague-Dawley rats were randomly divided into Sham-Vehicle group, Sham-NPS group, chronic constriction injury (CCI) group, Neuropeptide S low-dose group (NPSl group, 0.1 nmol/L) and Neuropeptide S high-dose group (NPSh group, 1 nmol/L), with 8 rats in each group. Pain-related behaviors, anxiety-related behaviours,and expression of NPS receptor (NPSR) in the left amygdaloid nucleus were measured on the 14th day via intracerebroventricular injection.Results Compared with the Sham-Vehicle group, the CCI group demonstrated significant pain and anxiety behaviors 14 days after operation (P<0.01), the NPSh group significantly relieved (P<0.01). And there was no significant difference between the NPSl group and the CCI group (P>0.05). Compared with the CCI group, NPSR expression in amygdaloid nucleus increased in the NPSh group. Conclusion NPS can dose-dependently relieve the pain and anxiety behaviors in CCI rats, which may be related with the increase of NPSR in amygdaloid nucleus.

Involvement of β3-adrenergic receptors in the control of food intake in rats

This study examined the food intake changes evoked by intracerebroventricular (icv) injection of a selective agonist (BRL37344, 2 and 20 nmol) or antagonist (SR59230A, 10 and 50 nmol) of β3-adrenergic receptors in 24-h fasted rats (adult male Wistar rats, 200-350 g, N = 6/treatment). The animals were also pretreated with saline icv (SAL) or SR59230A (50 nmol) followed by BRL37344 (20 nmol) or SAL in order to determine the selectivity of the effects evoked by BRL37344 on food intake or the selectivity of the effects evoked by SR59230A on risk assessment (RA) behavior. The highest dose of BRL37344 (N = 7) decreased food intake 1 h after the treatment (6.4 ± 0.5 g in SAL-treated vs 4.2 ± 0.8 g in drug-treated rats). While both doses of SR59230A failed to affect food intake (5.1 ± 1.1 g for 10 nmol and 6.0 ± 1.8 g for 50 nmol), this treatment reduced the RA frequency (number/30 min) (4 ± 2 for SAL-treated vs 1 ± 1 for 10 nmol and 0.5 ± 1 for 50 nmol SR59230A-treated rats), an ethological parameter related to anxiety. While pretreatment with SR59230A (7.0 ± 0.5 g) abolished the hypophagia induced by BRL37344 (3.6 ± 0.9 g), BRL37344 suppressed the reduction in RA frequency caused by SR59230A. These results show that the hypophagia caused by BRL37344 is selectively mediated by β3-adrenergic receptors within the central nervous system. Moreover, they suggest the involvement of these receptors in the control of anxiety.

Comparison of Alzheimer's disease animal model in BALB/c and Kunming mice by intracerebroventricular injection of β-amyloid / 军事医学科学院院刊

Objective:To compare the Alzheimer's disease model in two species of mice by intracerebroventricular injection of β-amyloid peptide 25-35(Aβ_(25～35)).Method:The step down test and Morris water-maze were used to investigate the influence of the mice's learning and memorizing ability after intracerebroventricular injection of β-amyloid.Results:Normal Kunming mice and BALB/c mice had no significant difference in step down test, but the space cognitive ability of Kunming mice was better than that of BALB/c mice. The learning response in step-down test and Morris water-maze is no influence in male, female BALB/c mice and female Kunming mice. Marked differences were observed in male Kunming mice in acquisition, performance and reversal of a place learning response in a Morris water-maze.Conclusion:The male Kunming mice is much better than female Kunming mice and male, female BALB/c mice in preparing Alzheimer's disease animal model by intracerebroventricular injection of Aβ_(25～35), and is the most suitable animal in this experiment.

Naloxone or Vagotomy Does Not Influence Centrally Octreotide-induced Inhibition of Gastric Acid Secretion in Rats / 华中科技大学学报（医学）（英德文版）

To investigate the effect of preceding naloxone injection into the third cerebroventricle or acute subdiaphragmatic vagotomy on the gastric acid secretion inhibited by the somatostatin analogue octreotide given by intracerebroventricular (icv) injection. The third ventricles were cannulated in male Wistar rats anesthetized with sodium pentobarbital. One week later, acute gastric lumen perfusion was carried out. The gastric perfusion samples were collected every 10 min and were fitrated by 0.01 mol/L NaOH to neuter. On the basis of subcutaneous injection of pentagastrin (G-5, 160 μ g/kg), icv injection of physiological saline (group A, n=20), icv injection of octreotide (0.05 μ g)(group B, n=20), icv injection of naloxone (2.5 μ g)+octreotide (0.05 μ g) (group C, n=20), acute subdiaphragmatic vagotomy+ icv injection of physiological saline (group D, n=20), or acute subdiaphragmatic vagotomy+icv injection of octreotide (0.05 μ g) (group E, n=20) were conducted. Before and after icy injection, 1-h total acid output (TAO) was determined and compared. The experimental data were expressed in change rate (%) of TAO. The change rates (%) of TAO were 4.60 % in group A, -20.35 % in group B, -18.06 % in group C, 5.01% in group D and -21.59 % in group E, respectively. Comparison of group B or C versus group A showed that P＜0.01 and comparison between the group E versus group D showed that P＜0.01. Whereas the differences between group C and group B, group E and group B were not statistically significant (P＞0.05 for all). The results indicate that the central inhibition of gastric acid secretion by octreotide may not be mediated by the endogenous opiate substance or its receptor and the peripheral pathway for icv injection of octreotide to suppress gastric acid secretion is via extra-vagus route.

Central N omega-nitro-L-arginine Methyl Ester Does not Influence Lithium-induced c-Fos and Conditioned Taste Aversion

LiCl at doses sufficient to induce conditioned taste aversion (CTA) causes c-Fos expression in the brain regions implicated in CTA formation. It has been reported that nitric oxide (NO) may play a role in CTA learning and LiCl increases both the synthesis and activity of NO synthase (NOS) in the brain. In this study, we examined the effect of central N omega-nitro-L- arginine methyl ester (L-NAME) on the brain c-Fos expression and CTA learning induced by lithium in rats. In the results, intracerebroventricular L-NAME given prior to lithium did not change either the lithium-induced CTA or c-Fos in the relevant brain regions. This suggests that the brain NO system may not be involved in the neuronal activation during lithium-induced CTA formation.

Effects of Ginseng Saponin on the Stress-Induced Plasma Corticosterone Levels in Mice / 신경정신의학

OBJECTIVES: The present study was designed to investigate the effect of ginseng saponin and its major active metabolite on the HPA axis under acute stress-i.c.v. injection stress, and immobilization stress, and to examine whether nitric oxide is involved in the mechanism of ginseng saponin on the HPA axis under acute stress. METHODS: In the experiment to study the effect of ginseng on HPA axis during stress, various dose of GTS were injected intracerebroventricularly(i.c.v.) or intraperitoneally(i.p.). Plasma corticosterone levels were measured 30 min after the i.c.v. injection stress. Immobilization stress was applied for 30 min and then blood was cellected for the assays of plasma corticosterone levels immediately after the completion of immobilization stress. To determine the active ginsenosides that can affect the stressinduced plasma corticosterone levels, various dose of each gisendosides(Rb1, Rb2, Rc, Re, Rf, Rg1, 20(S)-Rg3, and 20(R)-Rg3) were injected i.c.v. or i.p.. In the experiment to determine the involvement of the nitric oxide in the inhibitory effect of ginseng on the HPA, NG-Nitro-L-arginine methyl ester(L-NAME) and ginsenosides were coadministered i.c.v. or i.p., and plasma corticosterone levels were measured 30 min after stress was applied. RESULTS: First, the present study showed that ginseng total saponin, ginsenoside Rg3(S form), and ginsenoside Rc administered i.c.v. attenuated the intracerebroventricular injection stress-induced increase in plasma corticosterone levels, and these effects were removed by nitric oxide co-injection. Second, ginseng total saponin and ginsenoside Rc administered i.p. attenuated the immobilization stress-induced increase in plasma corticosterone levels, but ginsenoside Rg3(S form) did not attenuate the immobilization stress-induced increase in plasma corticosterone levels. The attenuative effects of ginseng total saponin and ginsenoside Rc in the immobilization stress-induced increase in plasma corticosterone levels were not affected by L-NAME co-injection. CONCLUSION: This study suggests that ginseng saponin attenuated stress-induced increase in plasma corticosterone levels and these effects were mediated by different mechanisms according to the components of ginseng saponin, and routes of administration.

Peripheral ?_1 and ?_2-adrenoceptors involved in attenuating the intracere broventricular histamine-induced carotid sinus baroreceptor reflex inhibition in rats / 中国药理学通报

Aim To determine the roles of peripheral ? 1 and ? 2 -adrenoceptors (? 1-AR,? 2-AR) in inhibition of carotid sinus barore ceptor reflex(CSR) induced by intracerebroventricular injection (icv) of histami ne (HA).Methods The left and right carotid sinus regions were i solated from the systemic circulation in 22 male Sprague-Dawley rats anesthetiz ed with pentobarbital sodium.The intracarotid sinus pressure (ISP) was altered in a stepwise ma nner in vivo.ISP-mean arterial pressure (MAP) relationship curve and its ch aracteristic parameters were constructed by fitting to the logistic function wit h five parameters.The changes in CSR performance induced by icv HA and the effec ts of pretreatment with ? 1-AR or ? 2-AR selective antagonist into the per ipheral vein on the responses of CSR to HA were examined.Results icv microinjection of HA (60 ?mol?L -1 in 5 ?l) significantly shifted the ISP-MAP relationship curve upwards (P0.05).Conclusion The intracerebroventricular administration of HA results in a rapid resetting of CSR and a decrease in reflex sensitivity, and the functions of both the peripheral ? 1-AR and ? 2-AR may attenuate CSR resetting induced by icv microinjection of HA. Furthermore,the peripheral ? 1-AR might play an important role in mediating the responses of CSR to central HA.