Tangeretin ameliorates renal failure via regulating oxidative stress, NF-κB-TNF-α/iNOS signalling and improves memory and cognitive deficits in 5/6 nephrectomized rats.

Chronic kidney disease (CKD) is a significant global health concern with limited treatment options. Oxidative stress and inflammatory responses have been implicated in the pathology of CKD. Patients with CKD are frequently affected with neurological complications that affect both the central and peripheral nervous system. Identification of effective treatment strategies are of much clinical value in the therapy of CKD. Tangeretin, a plant-derived flavonoid has been described to retain extensive pharmacological properties. In the present study, we explored whether tangeretin exerted protective effects in 5/6 nephrectomized rats. CKD was induced in Sprague-Dawley rats by 5/6 nephrectomy (Nx). Separate groups of 5/6 Nx rats were treated with tangeretin (50, 100 or 200 mg/kg b.wt.) or enalapril for 30 days (starting 5 days after surgery for 35 days). Control animals were not subjected to Nx nor were treated with tangeretin or enalapril. Renal dysfunction, as evinced by raised serum urea, serum creatinine, proteinuria, and histological alterations were significantly reduced by tangeretin and enalapril treatment. 5/6 Nx animals exhibited raised levels of malondialdehyde (MDA) and reactive oxygen species. Elevated TNF-α, nitric oxide (NO) and cytokines-IL-6 and IL-1ß with upregulated NF-κB/TNF-α/iNOS signalling pathways were effectively down-regulated by tangeretin. Cognitive disturbances and memory impairments observed in Nx rats were substantially improved by tangeretin. Collectively, the experimental data indicate that the anti-oxidant and anti-inflammatory effects of tangeretin effectively improved renal function and reduced the cognitive and memory impairments in CKD-induced animals.

[Small interfering RNA (siRNA) targeting vascular endothelial growth factor inhibits vascular leakage in brain of rats exposed to high altitude].

OBJECTIVE: To observe the change of expression of vascular endothelial growth factor (VEGF) and vascular leakage in the brain of rats exposed to high altitude with siRNA targeting vascular endothelial growth factor and explore the pathological mechanism and preventive approach of high altitude cerebral edema (HACE). METHODS: Fifty male Wistar rats were divided randomly into normal control group (Ncon), high altitude control group (Hcon), intraventricular normal saline control group (Scon), intraventricular siRNA group (CVI) and intravenous siRNA group (IVI). Rats in Ncon were raised normally. Rats in Hcon, Scon, CVI and IVI pretreated with intravenous injection of normal saline, intraventricular injection of normal saline, intraventricular injection of siRNA and intravenous injection of siRNA respectively were exposed to a low-pressure cabin mimicking a high altitude of 7000 m for 24 h. The ratio of dry and wet brain weight was calculated and the sodium fluorescein leakage calculated to evaluate the cerebral edema and the blood brain barrier permeability. Also the real-time quantitative RT-PCR was employed to detect the expression of VEGF mRNA and the Western blot the expression of VEGF. RESULTS: Compared with rats in NC, high altitude exposure led to a significant increase in the levels of VEGF mRNA (from 21.6 + or - 3.5 K copies/microg to 36.3 + or - 3.9 K copies/microg, P < 0.01) and protein (from 48 + or - 0.09 to 0.77 + or - 0.12, P < 0.01) in rat brain and fluorescence intensity of sodium fluorescein increased significantly (from 548 + or - 48 rfu/mg to 674 + or - 32 rfu/mg, P < 0.01). Intravenous injection of siRNA targeting to VEGF caused no significant change of expression VEGF mRNA and protein and fluorescence intensity of sodium fluorescein in rat brain (P > 0.05, respectively). While compared with rats in HC, intraventricular injection of siRNA targeting to VEGF caused the significant reduction of expression of VEGF mRNA (from 36.3 + or - 3.9 to 19.9 + or - 4.3, P < 0.01) and protein (from 0.77 + or - 0.12 to 0.44 + or - 0.13, P < 0.01) and fluorescence intensity of sodium fluorescein (from 674 + or - 32 rfu/mg to 542 + or - 77 rfu/mg, P < 0.05) in rat brain. There were no significant change in the ratio of dry and wet brain weight among five groups. CONCLUSION: VEGF may play a key role in the pathologic process of HACE. Intraventricular injection of siRNA targeting to VEGF inhibits the expression of VEGF and prevent the high altitude-induced vascular leakage. These findings might provide a basis for new preventive approaches of cerebral edema.

[Change of Rho kinase activity in brain tissue in high altitude condition and its relationship with high altitude cerebral edema: experiment with rats].

OBJECTIVE: To observe the change of Rho kinase activity in brain tissue in the high altitude condition and its relationship with blood brain barrier permeability and high altitude cerebral edema (HACE), and to explore the pathological mechanism of HACE. METHODS: 30 Wistar rats were divided randomly into 3 equal groups, high altitude (HA) group put in low pressure cabin mimicking high altitude of 7000 m for 24 hr and then gradually exposed to higher pressure until the normal pressure, fasudil group undergoing intraperitoneal injection of fasudil hydrochloride 30 mg/kg, a Rho-associated coiled-coil-containing protein kinase (ROCK) inhibitor, and then treated as the HA group, and normal control group (HC group). Five rats from each were decapitated with their brains taken out. The ratio of dry brain weight and wet brain weight was calculated. Western blotting was used to detect the expression of ROCK. Another 5 rats from each groups underwent injection of sodium fluorescein into the caudal vein and then the rats were decapitated to examine the natrium (sodium) fluorescence index (NaFI) of the central brain slice so as to observe the blood brain barrier permeability. RESULTS: The ROCK activity in brain tissue, ratio of dry and wet brain weight and NaFI of the HA group were significantly higher than those of the HC group (all P<0.001), and ROCK activity in brain tissue, ratio of dry and wet brain weight and NaFI of the fasudil group were all significantly lower than those of the HA group (all P<0.001) and not significantly different from those of the HC group (all P>0.05). CONCLUSIONS: ROCK in brain tissue is activated in high altitude condition, which may play a key role in the development of HACE.

Neuroprotective action and mechanistic evaluation of protodioscin against rat model of Parkinson's disease.

BACKGROUND: Parkinson's disease (PD) is the most widespread motor-affecting disease affecting majorly middle- and late age population. Thus, in the current study, we intended to explore the neuroprotective effect of protodioscin (Proto) against 6-hydroxydopamine (6-OHDA)-induced PD rat model. METHODS: After induction of PD with the injection of 6-OHDA, the different dose of Proto was administered for the duration of experimental protocol (2 months). We have scrutinized the consequence of Proto on the cognitive behaviours via Moris water maze (MWM), and recognition of novel objects and its location tasks. The effect of Proto was also investigated on the expression of Nrf2 in human neuroblastoma SHSY5Y cells via western blot analysis. RESULTS: The results showed significant decrease in travelled distance as compared by the lesion treated group. Further significant difference was revealed in the latency time to detect the platform that is visible and it confirmed that, there were no noteworthy dissimilarity was observed in the visual and motor function ability. The result also suggests that, the activation of Nrf2 is the possible mechanism of neuroprotection of Proto against PD. CONCLUSION: As a concluding remark, the present study confirmed the neuroprotective role of Proto against PD both in in vitro and in vivo models.

[The effect of fastigial nucleus electrical stimulation on the therapeutic window of opportunity for intervention of focal cerebral ischemia].

OBJECTIVE: To investigate the effect of cerebellar fastigial nucleus (FN) electrical stimulation on the therapeutic window of opportunity for intervention of focal cerebral ischemia. METHODS: Thirty-five healthy male Wistar rats were divided into focal cerebral ischemia/reperfusion group (I/R group, undergoing ischemia by embolism of middle cerebral artery for 3, 6 or 8 hours and then undergoing reperfusion for 24 hours, thus subdivided into I/R 3 hours, 6 hours, and 8 hours subgroups of 5 rats), focal cerebral ischemia/reperfusion plus FN electrical stimulation group (I/R-FN group, n = 15, undergoing FN electrical stimulation followed by focal cerebral ischemia/reperfusion as in the I/R group), and sham operation group (n = 5). Twenty-four hours after the reperfusion or sham operation, the rats were killed. The brain slices underwent Nissl's staining. Two slices of each rat were examined to observe the neuronal number and morphology, and the status or Nissl's staining, and make a scoring of the affected somatosensory cortex. RESULTS: The survival rates of neurons of the I/R 3, 6 and 8 hours subgroups 3.2% +/- 11.3%, 2.6% +/- 4.5% and 3.8% +/- 3.2% respectively without a significant difference between any 2 subgroups (all P > 0.05). The scores of these 3 subgroups all reached the highest grade (4.0 +/- 0.0). The neuron survival rate of the I/R FN 3 hours subgroup was 64.2% +/- 11.3%, significantly higher than those or other I/R subgroup at the same time point (all P < 0.01), however, the neurons being obviously shrunken. The score of the I/R FN 3 hours subgroup 2.1 +/- 0.2, significantly lower than that of the I/R 3 hours subgroup (P < 0.01). The neuron survival rate of the I/R FN 6 hours subgroup was 32.8% +/- 6.5%, significantly higher than that of the I/R 6 hours subgroup (P < 0.05), however, the neurons being shrunken and irregular in shape. The score of the I/R FM subgroup was 3.0 +/- 0.0, significantly lower than that of the I/R 6 hours subgroup (P < 0.05). The I/R FN 8 hours subgroup showed a neuron survival rate of 4.1% +/- 3.5%, not significantly different from that of the I/R 9 hours subgroup (P > 0.05), and the same score as that of the I/R 8 hours subgroup. The sham operation group showed a survival rate of neurons of 96.9% +/- 17.3% and a score of 0.00 +/- 0.00. CONCLUSION: FN electrical stimulation prolongs the therapeutic window of opportunity for intervention of focal cerebral ischemia. The complete recovery of survived neurons may need further interventions.

The interaction between the oxytocin and pain modulation in headache patients.

Oxytocin (OXT), a nonapeptide hormone of posterior pituitary, reaches the central nervous system from systemic blood circulation with a difficulty because of the blood-brain barrier (BBB). The interest has been expressed in the use of the nasal route for delivery of OXT to the brain directly, exploiting the olfactory pathway. Our previous study has demonstrated that OXT in the central nervous system rather than the blood circulation plays an important role in rat pain modulation. The communication tried to investigate the interaction between the OXT and pain modulation in Chinese patients with headache to understand the OXT effect on human pain modulation. The results showed that (1) intranasal OXT could relieve the human headache in a dose-dependent manner; (2) OXT concentration in both plasma and cerebrospinal fluid (CSF) increased significantly in headache patients in relation with the pain level; and (3) there was a positive relationship between plasma and CSF OXT concentration in headache patients. The data suggested that intranasal OXT, which was delivered to the central nervous system through olfactory region, could treat human headache and OXT might be a potential drug of headache relief by intranasal administration.

Effect of intranasal arginine vasopressin on human headache.

Arginine vasopressin (AVP), a nonapeptide hormone of posterior pituitary, reaches the central nervous system from systemic blood circulation with a difficulty because of the blood-brain barrier (BBB). The interest has been expressed in the use of the nasal route for delivery of AVP to the brain directly, exploiting the olfactory pathway. Our previous study has demonstrated that AVP in the brain rather than the spinal cord and blood circulation plays an important role in rat pain modulation. For understanding the role of AVP on pain modulation in human, the communication tried to investigate the effect of intranasal AVP on human headache. The results showed that (1) AVP concentration in both plasma and cerebrospinal fluid (CSF) increased significantly in headache patients, who related with the headache level; (2) there was a positive relationship between plasma and CSF AVP concentration in headache patients; and (3) intranasal AVP could relieve the human headache in a dose-dependent manner. The data suggested that intranasal AVP, which was delivered to the brain through olfactory region, could treat human headache and AVP might be a potential drug of pain relief by intranasal administration.