Hypobaric hypoxia induced fear and extinction memory impairment and effect of Ginkgo biloba in its amelioration: Behavioral, neurochemical and molecular correlates.

Regulated fear and extinction memory is essential for balanced behavioral response. Limbic brain regions are susceptible to hypobaric hypoxia (HH) and are putative target for fear extinction deficit and dysregulation. The present study aimed to examine the effect of HH and Ginkgo biloba extract (GBE) on fear and extinction memory with the underlying mechanism. Adult male Sprague-Dawley rats were evaluated for fear extinction and anxious behavior following GBE administration during HH exposure. Blood and tissue (PFC, hippocampus and amygdala) samples were collected for biochemical, morphological and molecular studies. Results revealed deficit in contextual and cued fear extinction following 3 days of HH exposure. Increased corticosterone, glutamate with decreased GABA level was found with marked pyknosis, decrease in apical dendritic length and number of functional spines. Decline in mRNA expression level of synaptic plasticity genes and immunoreactivity of BDNF, synaptophysin, PSD95, spinophilin was observed following HH exposure. GBE administration during HH exposure improved fear and extinction memory along with decline in anxious behavior. It restored corticosterone, glutamate and GABA levels with an increase in apical dendritic length and number of functional spines with a reduction in pyknosis. It also improved mRNA expression level and immunoreactivity of neurotrophic and synaptic proteins. The present study is the first which demonstrates fear extinction deficit and anxious behavior following HH exposure. GBE administration ameliorated fear and extinction memory dysregulation by restoration of neurotransmitter levels, neuronal pyknosis and synaptic connections along with improved neurotrophic and synaptic protein expressions.

In ovo Sound Stimulation Mediated Regulation of BDNF in the Auditory Cortex and Hippocampus of Neonatal Chicks.

Brain-derived neurotrophic factor (BDNF) is known to mediate activity-dependent changes in the developing auditory system. Its expression in the brainstem auditory nuclei, auditory cortex and hippocampus of neonatal chicks (Gallus gallus domesticus) in response to in ovo high intensity sound exposure at 110 dB (arrhythmic sound: recorded traffic noise, 30-3000 Hz with peak at 2700 Hz, rhythmic sound: sitar music, 100-4000 Hz) was examined to understand the previously reported altered volume and neuronal number in these regions. In the brainstem auditory nuclei, no mature BDNF, but proBDNF at the protein level was detected, and no change in its levels was observed after in ovo sound stimulation (music and noise). Increased ProBDNF protein levels were found in the auditory cortex in response to arrhythmic sound, along with decreased levels of one of the BDNF mRNA transcripts, in response to both rhythmic and arrhythmic sound stimulation. In the hippocampus, increased levels of mature BDNF were found in response to music. Expression microarray analysis was performed to understand changes in gene expression in the hippocampus in response to music and noise, followed by gene ontology analysis showing enrichment of probable signaling pathways. Differentially expressed genes like CAMK1 and STAT1 were found to be involved in downstream signaling on comparing music versus noise-exposed chicks. In conclusion, we report that BDNF is differentially regulated in the auditory cortex at the transcriptional and post-translational level, and in the hippocampus at the post-translational level in response to in ovo sound stimulation.

Fisetin attenuates isoproterenol-induced cardiac ischemic injury in vivo by suppressing RAGE/NF-κB mediated oxidative stress, apoptosis and inflammation.

BACKGROUND: The therapeutic options for the reducing the damage caused by myocardial ischemia are limited and not devoid of adverse effects. The role of the flavanoid, fisetin, predominantly found in strawberry and apple, is yet to be explored in the heart. STUDY DESIGN: Male Wistar rats (n = 48) were administered fisetin (10, 20 & 40 mg/kg/day, orally) or vehicle for 28 days while ISO, 85 mg/kg, subcutaneously, was also administered at 24 h interval on the 27th and 28th day. On the 29th day, rats were anaesthetized and right carotid artery was cannulated to record hemodynamic parameters. Subsequently, blood sample was collected and heart was removed to evaluate various parameters. RESULTS: Fisetin at doses of 10 and 20 mg/kg reversed ISO induced detrimental alterations in blood pressure and left ventricular pressures and reduced the myocardial injury markers CK-MB and LDH in the serum. These findings were supported by amelioration of ISO induced histological and ultrastructural damage by fisetin. The disequilibrium in the levels of pro and anti oxidants in the myocardial tissue caused by ISO was also normalized Furthermore, apoptosis was evident from enhanced DNA fragmentation and raised pro-apoptotic proteins (bax, caspase-3, cytochrome-c) as well as suppressed anti-apoptotic protein (Bcl-2) in case of ISO treatment which again was reversed by fisetin. A molecular mechanism for this protection was elucidated as downregulation of RAGE and NF-κB However fisetin at 40 mg/kg revealed a deteriorating effect which was similar to ISO group of rats. CONCLUSION: Hence, through our study, the role of fisetin in cardioprotection has been uncovered via a molecular pathway.

Galangin ameliorates cisplatin induced nephrotoxicity in vivo by modulation of oxidative stress, apoptosis and inflammation through interplay of MAPK signaling cascade.

BACKGROUND AND PURPOSE: Cisplatin is a widely used chemotherapeutic agent but now-a-days its usage is limited in clinical chemotherapy because of its severe nephrotoxic effect on renal tissues. Galangin, a flavonoid obtained from ginger family has been demonstrated to have antioxidant, anti-apoptotic and anti-inflammatory properties. This study is aimed to investigate the possible ameliorative effect of galangin in a rodent model of cisplatin-induced nephrotoxicity. MATERIAL AND METHODS: Adult male albino wistar rats were divided into six groups (n=6) viz normal, cisplatin-control, galangin (25, 50 and 100mg/kg p.o.) and per se (100mg/kg galangin, p.o.). Galangin was administrated orally to the rats for a period of 10 days. On the 7th day of the treatment, nephrotoxicity was induced in all the groups by a single dose of cisplatin (8mg/kg, i.p.) (except normal and per se group). On the 11th day, the rats were anaesthetized and blood was withdrawn via direct heart puncture for biochemical estimation. Rats were sacrificed and kidneys were isolated and preserved for evaluation of histopathological, ultra structural immunohistochemical studies and western blot analysis. RESULTS: Cisplatin significantly impaired renal function and increased oxidative stress and inflammation. It also increased expression of pro-apoptotic proteins Bax and caspase-3 and decreased the expression of the anti-apoptotic protein Bcl-2. Histological and ultrastructural findings were also supportive of renal tubular damage. Pretreatment with galangin (100mg/kg p.o.) preserved renal function, morphology, suppressed oxidative stress, inflammation and the activation of apoptotic pathways. TUNEL assay showed decreased DNA fragmentation on galangin pre-treatment. Furthermore, galangin (100mg/kg) pre-treatment also reduced the expression of NFκB along with proteins MAPK pathway i.e. p38, JNK and ERK1/2. CONCLUSION: In conclusion, Galangin (100mg/kg, p.o.) significantly ameliorated cisplatin induced nephrotoxicity by suppressing MAPK induced inflammation and apoptosis.

High resolution 1H NMR-based metabonomic study of the auditory cortex analogue of developing chick (Gallus gallus domesticus) following prenatal chronic loud music and noise exposure.

Proper functional development of the auditory cortex (ACx) critically depends on early relevant sensory experiences. Exposure to high intensity noise (industrial/traffic) and music, a current public health concern, may disrupt the proper development of the ACx and associated behavior. The biochemical mechanisms associated with such activity dependent changes during development are poorly understood. Here we report the effects of prenatal chronic (last 10 days of incubation), 110dB sound pressure level (SPL) music and noise exposure on metabolic profile of the auditory cortex analogue/field L (AuL) in domestic chicks. Perchloric acid extracts of AuL of post hatch day 1 chicks from control, music and noise groups were subjected to high resolution (700MHz) (1)H NMR spectroscopy. Multivariate regression analysis of the concentration data of 18 metabolites revealed a significant class separation between control and loud sound exposed groups, indicating a metabolic perturbation. Comparison of absolute concentration of metabolites showed that overstimulation with loud sound, independent of spectral characteristics (music or noise) led to extensive usage of major energy metabolites, e.g., glucose, ß-hydroxybutyrate and ATP. On the other hand, high glutamine levels and sustained levels of neuromodulators and alternate energy sources, e.g., creatine, ascorbate and lactate indicated a systems restorative measure in a condition of neuronal hyperactivity. At the same time, decreased aspartate and taurine levels in the noise group suggested a differential impact of prenatal chronic loud noise over music exposure. Thus prenatal exposure to loud sound especially noise alters the metabolic activity in the AuL which in turn can affect the functional development and later auditory associated behaviour.

Effects of Trigonella foenum-graecum (L.) on retinal oxidative stress, and proinflammatory and angiogenic molecular biomarkers in streptozotocin-induced diabetic rats.

The aim of the present study was to investigate the protective effects of Trigonella foenum-graecum Linn. (fenugreek) in Streptozotocin-induced diabetic rat retina. Fenugreek (100 and 200 mg/kg body weights) treatment was carried out for 24 weeks and evaluated for inflammatory [tumor necrosis factor (TNF)-α and interleukin (IL)-1ß] and angiogenic [vascular endothelial growth factor (VEGF) and protein kinase C (PKC)-ß] molecular biomarkers. Retinal oxidative stress was evaluated by estimating antioxidant (Glutathione, Superoxide dismutase, and Catalase) parameters. Fluorescein angiography was performed to detect retinal vascular leakage. Electron microscopy was performed to determine basement membrane thickness. In the present study, significant rises in the expressions of retinal inflammatory (TNF-α and IL-1ß) and angiogenic (VEGF and PKC-ß) molecular biomarkers were observed in diabetic retinae compared with normal retinae. However, fenugreek-treated retinae showed marked inhibition in the expression of inflammatory and angiogenic molecular biomarkers. Moreover, results from the present study showed positive modulatory effects of fenugreek on retinal oxidative stress. Fluorescein angiograms and fundus photographs obtained from diabetic retinae showed retinal vascular leakage. On the other hand, fenugreek-treated retinae did not show vascular leakage. Further, thickened BM was recorded in diabetic retina compared with normal retinae. However, fenugreek-treated retinae showed relatively lesser thickening of capillary BM. In conclusion, it may be postulated that fenugreek has great potential in preventing diabetes-induced retinal degeneration in humans after regular consumption in the specified dosage.

Prenatal loud music and noise: differential impact on physiological arousal, hippocampal synaptogenesis and spatial behavior in one day-old chicks.

Prenatal auditory stimulation in chicks with species-specific sound and music at 65 dB facilitates spatial orientation and learning and is associated with significant morphological and biochemical changes in the hippocampus and brainstem auditory nuclei. Increased noradrenaline level due to physiological arousal is suggested as a possible mediator for the observed beneficial effects following patterned and rhythmic sound exposure. However, studies regarding the effects of prenatal high decibel sound (110 dB; music and noise) exposure on the plasma noradrenaline level, synaptic protein expression in the hippocampus and spatial behavior of neonatal chicks remained unexplored. Here, we report that high decibel music stimulation moderately increases plasma noradrenaline level and positively modulates spatial orientation, learning and memory of one day-old chicks. In contrast, noise at the same sound pressure level results in excessive increase of plasma noradrenaline level and impairs the spatial behavior. Further, to assess the changes at the molecular level, we have quantified the expression of functional synapse markers: synaptophysin and PSD-95 in the hippocampus. Compared to the controls, both proteins show significantly increased expressions in the music stimulated group but decrease in expressions in the noise group. We propose that the differential increase of plasma noradrenaline level and altered expression of synaptic proteins in the hippocampus are responsible for the observed behavioral consequences following prenatal 110 dB music and noise stimulation.

Cardioprotective effect of root extract of Picrorhiza kurroa (Royle Ex Benth) against isoproterenol-induced cardiotoxicity in rats.

Normal rats pre-treated with P. kurroa (200 mg/kg) alone did not showed significant change, however, isoproterenol (ISP) administration resulted in hemodynamic and left ventricular dysfunction, oxidative stress, and lipid peroxidation. Such cardiac dysfunction was significantly prevented by P. kurroa root extract pre-treatment. Pre-treatment significantly attenuated the ISP-induced oxidative stress by restoring myocardial superoxide dismutase, catalase, and glutathione peroxidase enzymes except reduced glutathione content. P. kurroa pre-treatment markedly attenuated the ISP-induced rise in lipid peroxidation, thereby prevented leakage of myocyte creatine kinase-MB and lactate dehydrogenase enzymes. The results suggest that P. kurroa root extract possesses significant cardioprotective effect, which may be attributed to its antioxidant, anti-peroxidative, and myocardial preservative properties.

Retinoprotective effects of Moringa oleifera via antioxidant, anti-inflammatory, and anti-angiogenic mechanisms in streptozotocin-induced diabetic rats.

PURPOSE: The present study was aimed to evaluate the retinoprotective effects of Moringa oleifera (MO) in Streptozotocin-induced diabetic rats. METHODS: The study was continued for 24 weeks and evaluated for inflammatory (tumor necrosis factor [TNF]-α and interleukin [IL]-1ß, angiogenic (vascular endothelial growth factor [VEGF] and protein kinase C [PKC]-ß) and antioxidant (Glutathione, Superoxide dismutase, and Catalase) parameters. Retinal leakage was checked by Fluorescein angiography (FA) and fundus photographs were evaluated for retinal vessel caliber (arteriolar and venular). Transmission electron microscopy was done to determine basement membrane (BM) thickness. RESULTS: The results of the present study showed potential hypoglycemic and retinal antioxidant effects of MO. In the present study, a significant rise in the expression of retinal inflammatory (TNF-α and IL-1ß) and angiogenic (VEGF and PKC-ß) parameters was observed in diabetic retinae as compared to normal retinae. However, MO-treated retinae showed marked inhibition in the expression of inflammatory and angiogenic parameters. Further, in the present study, diabetic retinae showed dilated retinal vessels as compared to normal. However, MO-treated retinae showed marked prevention in the dilatation of retinal vessels. Fluorescein angiograms obtained from diabetic retinae showed leaky and diffused retinal vasculature. On the other hand, MO-treated retinae showed intact retinal vasculature. Further, results of the transmission electron microscopy study showed thickened capillary BM in the diabetic retina as compared to normal retinae. However, treatment with MO prevented thickening of capillary BM. CONCLUSION: Our result suggests that MO may be useful in preventing diabetes induced retinal dysfunction.

Green tea prevents hyperglycemia-induced retinal oxidative stress and inflammation in streptozotocin-induced diabetic rats.

PURPOSE: Our objective was to investigate the effect of green tea (GT) on diabetes-induced retinal oxidative stress and proinflammatory parameters in rats. METHODS: Treatment (200 mg/kg body weight) was carried out for a period of 16 weeks in streptozotocin-induced diabetic rats and was evaluated for hypoglycemic, antioxidant [reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT)] and anti-inflammatory [tumor necrosis factor (TNF) α, vascular endothelial growth factor (VEGF)] activity. Histological changes were evaluated by transmission electron microscopy. RESULTS: Retinal GSH levels were 1.5-fold lower in diabetic rats as compared to normal rats (p < 0.05). However, in GT-treated rats, retinal GSH levels were restored close to those of the normal group. The antioxidant enzymes SOD and CAT showed a more than 2-fold decrease in activity in diabetic retinae as compared to normal retinae (p < 0.05). Both SOD and CAT enzymatic activities were restored close to normal in the GT-treated group. Expression of proinflammatory parameters (TNF-α and VEGF) was significantly inhibited in GT-treated retinae as compared to diabetic retinae (p < 0.05). Moreover, GT treatment prevented retinal capillary basement membrane thickness. CONCLUSION: The beneficial effects of GT suggest its potential role in the prevention and treatment of diabetic retinopathy in human subjects.

Ocimum sanctum extracts attenuate hydrogen peroxide induced cytotoxic ultrastructural changes in human lens epithelial cells.

Hydrogen peroxide (H2O2) is the major oxidant involved in cataract formation. The present study investigated the effect of an aqueous leaf extract of Tulsi (Ocimum sanctum) against H2O2 induced cytotoxic changes in human lens epithelial cells (HLEC). Donor eyes of the age range 20-40 years were procured within 5-8 h of death. After several washings with gentamicin (50 mL/L) and betadine (10 mL/L), clear transparent lenses (n=6 in each group) were incubated in Dulbecco's modified Eagle's medium (DMEM) alone (normal) or in DMEM containing 100 microm of H2O2 (control) or in DMEM containing both H2O2 (100 microm) and 150 microg/mL of Ocimum sanctum extract (treated) for 30 min at 37 degrees C with 5% CO2 and 95% air. Following incubation, the semi-hardened epithelium of each lens was carefully removed, fixed and processed for electron microscopic studies. Thin sections (60-70 mm) were contrasted with uranyl acetate and lead citrate and viewed under a transmission electron microscope. Normal epithelial cells showed intact, euchromatic nucleus with few small vacuoles (diameter 0.58+/-0.6 microm) in well-demarcated cytoplasm. After treatment with H2O2, they showed pyknotic nuclei with clumping of chromatin and ill-defined edges. The cytoplasm was full of vacuoles (diameter 1.61+/-0.7 microm). The overall cellular morphology was typical of dying cells. Treatment of cells with Ocimum sanctum extract protected the epithelial cells from H2O2 insult and maintained their normal architecture. The mean diameter of the vacuoles was 0.66+/-0.2 microm. The results indicate that extracts of O. sanctum have an important protective role against H2O2 injury in HLEC by maintaining the normal cellular architecture. The protection could be due to its ability to reduce H2O2 through its antioxidant property and thus reinforcing the concept that the extracts can penetrate the HLEC membrane.

Effect of prenatal auditory stimulation on numerical synaptic density and mean synaptic height in the posthatch Day 1 chick hippocampus.

Previous studies on prenatal auditory stimulation by species-specific sound or sitar music showed enhanced morphological and biochemical changes in chick hippocampus, which plays an important role in learning and memory. Changes in the efficiency of synapses, synaptic morphology and de novo synapse formation affects learning and memory. Therefore, in the present study, we set out to investigate the mean synaptic density and mean synaptic height at posthatch Day 1 in dorsal and ventral part of chick hippocampus following prenatal auditory stimulation. Fertilized 0 day eggs of domestic chick incubated under normal conditions were exposed to patterned sounds of species-specific and sitar music at 65 dB levels for 15 min/h round the clock (frequency range: 100-6300 Hz) from embryonic Day 10 till hatching. The synapses identified under transmission electron microscope were estimated for their numerical density by physical disector method and also the mean synaptic height calculated. Our results demonstrate a significant increase in mean synaptic density with no alterations in the mean synaptic height following both types of auditory stimulation in the dorsal as well as ventral part of the hippocampus. The observed increase in mean synaptic density suggests enhanced synaptic substrate to strengthen hippocampal function.

Calbindin D-28K and parvalbumin expression in embryonic chick hippocampus is enhanced by prenatal auditory stimulation.

Calcium-binding proteins (CaBPs) buffer excess of cytosolic Ca(2+), which accompanies neuronal activity following external stimuli. Prenatal auditory stimulation by species-specific sound and music influences early maturation of the auditory pathway and the behavioral responses in chicks. In this study, we determined the volume, total number of neurons, proportion of calbindin D-28K and parvalbumin-positive neurons along with their levels of expression in the developing chick hippocampus following prenatal auditory stimulation. Fertilized eggs of domestic chicks were exposed to sounds of either species-specific calls or sitar music at 65 dB for 15 min/h round the clock from embryonic day (E) 10 until hatching. Hippocampi of developmental stages (E12, E16 and E20) were examined. With an increase in embryonic age during normal development, the hippocampus showed an increase in its volume, total number of neurons as well as in the neuron proportions and levels of expression of calbindin D-28K and parvalbumin. A significant increase of volume at E20 was noted only in the music-stimulated group compared to that of their age-matched control (p<0.05). On the other hand, both auditory-stimulated groups showed a significant increase in the proportion of immunopositive neurons and the levels of expression of calbindin D-28K and parvalbumin as compared to the control at all developmental stages studied (p<0.003). The increase in proportions of CaBP neurons during development and in the sound-enriched groups suggests an activity-dependent increase in Ca(2+) influx. The enhanced expression of CaBPs may help in cell survival by preventing excitotoxic death of neurons during development and may also be involved in long-term potentiation.

Prenatal acoustic stimulation influences neuronal size and the expression of calcium-binding proteins (calbindin D-28K and parvalbumin) in chick hippocampus.

Prenatal auditory enrichment by species-specific sounds and sitar music enhances the expression of immediate early genes, synaptic proteins and calcium binding proteins (CaBPs) as well as modifies the structural components of the brainstem auditory nuclei and auditory imprinting area in chicks. There is also facilitation of postnatal auditory preference of the chicks to maternal calls following both types of sound stimulation indicating prenatal perceptual learning. To examine whether the sound enrichment protocol also affects the areas related to learning and memory, we assessed morphological changes in the hippocampus at post-hatch day 1 of control and prenatally sound-stimulated chicks. Additionally, the proportions of neurons containing calbindin D-28K and parvalbumin immunoreactivity as well as their protein levels were determined. Fertilized eggs of domestic chick were incubated under normal conditions of temperature, humidity, forced draft of air as well as light and dark (12:12h) photoperiods. They were exposed to patterned sounds of species-specific and sitar music at 65 dB for 15 min per hour over a day/night cycle from day 10 of incubation till hatching. The hippocampal volume, neuronal nuclear size and total number of neurons showed a significant increase in the music-stimulated group as compared to the species-specific sound-stimulated and control groups. However, in both the auditory-stimulated groups the protein levels of calbindin and parvalbumin as well as the percentage of the immunopositive neurons were increased. The enhanced proportion of CaBPs in the sound-enriched groups suggests greater Ca(2+) influx, which may influence long-term potentiation and short-term memory.