Neuroprotective Effects of Chrysin Mediated by Estrogenic Receptors Following Cerebral Ischemia and Reperfusion in Male Rats.

INTRODUCTION: Ischemic stroke is one of the leading causes of morbidity and mortality worldwide. Neuroprotective strategies were reported to attenuate cognitive deficits after ischemic incidents. Here we studied the neuroprotective potential of chrysin in a rat model of cerebral Ischemia/Reperfusion (I/R) in the presence or absence of Estrogen Receptors (ERs). METHODS: Adult male Wistar rats were pretreated with chrysin (CH) (CH; 30 mg/kg; gavage; for 21 consecutive days) alone or with selective ERs antagonists (ERα antagonist MPP; ERß antagonist PHTPP; IP) or nonselective ERs antagonist (ICI182780; IP). Then, the bilateral common carotid arteries were occluded for 20 min, which was followed by 72 h reperfusion. Subsequently, cognitive performance was evaluated by Morris Water Maze (MWM) and shuttle box tasks, and afterward, their hippocampi were removed for ELISA assays and H&E staining. Oxidative indicators Malondialdehyde (MDA) and Glutathione Peroxidase (GPx), as well as inflammation mediators interleukin (IL)-1ß and tumor necrosis factor-alpha (TNFα), were measured using commercial kits. RESULTS: Results of the current study showed that the anti-oxidative and anti-inflammatory properties of CH are possible mechanisms that could improve cognitive deficits and prevent neuronal cell death following I/R (P<0.001). These effects were reversed by ICI182780 (P>0.05). Furthermore, when chrysin was co-treated with ERß antagonist, PHTPP showed a weak neuroprotective effect in I/R rats. However, these parameters were not significantly different when chrysin was combined with ERα antagonist MPP. CONCLUSION: Our data confirm that chrysin could potentially serve as a neuroprotective agent against devastating effects of cerebral I/R injury, which may be mediated via its interaction with ERs, especially ERß.

Protective effects of Chrysin against memory impairment, cerebral hyperemia and oxidative stress after cerebral hypoperfusion and reperfusion in rats.

Stroke is devastating and a leading cause of morbidity and mortality worldwide. Cerebral ischemia-reperfusion and its subsequent reactive hyperemia lead to neuronal damage in the hippocampus and cognitive decline. Chrysin (5, 7-dihydroxyflavone) is a well-known member of the flavonoid family with antioxidant and neuroprotective effects. Therefore, in the present study, the aim was to investigate whether chrysin will be able to recover the brain function caused by ischemia-reperfusion (I/R) in rats. Adult male Wistar rats (250-300 g) were randomly divided into five groups: and submitted to cerebral I/R or a sham surgery after three-weeks of pretreatment with chrysin (CH; 10, 30 and 100 mg/kg; P.O.) and/or normal saline containing %5 DMSO. Subsequently, sensorimotor scores, cognition, local cerebral blood flow, extracellular single unit, and histological parameters were evaluated following I/R. Hippocampus was used to evaluate biomarkers including: oxidative stress parameters and prostaglandin E2 (PGE2) using ELISA kits. Data showed that pretreatment with chrysin significantly improved sensorimotor signs, passive avoidance memory, and attenuated reactive hyperemia, and increased the average number of spikes/bin (p < 0.001). Furthermore, chrysin pre-treatment significantly decreased the levels of MDA, NO, and PGE2 (p < 0. 001), while increased the levels of GPX and the number of surviving cells in the hippocampal CA1 region (p < 0.01, p < 0.001; respectively). This study demonstrates that chrysin may have beneficial effects in the treatment of cognitive impairment and help recover the brain dysfunction induced by I/R.

Chrysin prevents cognitive and hippocampal long-term potentiation deficits and inflammation in rat with cerebral hypoperfusion and reperfusion injury.

INTRODUCTION: Ischemic stroke is one of the leading causes of death worldwide, and extensive efforts have focused on the neuroprotective strategies to minimize complications due to ischemia. This study aimed to examine neuroprotective potential of chrysin, as a natural potent antioxidative and anti-inflammatory agent in an animal model of bilateral common carotid artery occlusion and reperfusion (BCCAO/R). METHODS: Adult male Wistar rats (250-300 g) were randomly divided into 6 groups and submitted to either sham surgery or BCCAO/R after pretreatment with chrysin (10, 30 and 100 mg/kg, once daily, for 21 consecutive days) or saline containing %5 DMSO. To make the animal model of BCCAO/R, bilateral common carotid arteries were occluded for 20 min, followed by reperfusion. Subsequently, spatial cognitive performance was evaluated in a Morris water maze (MWM), hippocampal long-term potentiation (LTP) was recorded from hippocampal dentate gyrus region, after then the hippocampal tissue content of IL-1ß and TNF-α were assayed using ELISA kits. RESULTS: The results showed that pretreatment with chrysin significantly prevented BCCAO/R-induced cognitive and hippocampal LTP impairments (p < 0.001). Additionally, BCCAO/R- induced elevation in hippocampal content of IL-1ß and TNF-α significantly (p < 0.01, p < 0.01 respectively) while pre-treatment with chrysin restored them (p < 0.01). CONCLUSION: Our data confirm that chrysin could prevent brain inflammation and thereby prevents cognitive and LTP impairments due to cerebral ischemia. So it could be a promising neuroprotective agent against cerebrovascular insufficiency states.

Improvement in Memory and Brain Long-term Potentiation Deficits Due to Permanent Hypoperfusion/Ischemia by Grape Seed Extract in Rats.

OBJECTIVE(S): Cerebral hypoperfusion/ischemia (CHI) is a neurological disease where impaired hippocampus electrical activity and cognition caused by a serial pathophysiological events. This study aimed to evaluate the effects of chronic oral administration of grape seed extract (GSE) on passive avoidance memory and long-term potentiation (LTP) after permanent bilateral common carotid arteries occlusion (2CCAO) in male adult rats. MATERIALS AND METHODS: Thirty-two adult male Wistar rats were randomly divided into: 1) Sham+Veh, 2) Isch+Veh, 3) Sham+GSE, 4) Isch+GSE. In order to make 2CCAO as an animal model of CHI, carotid arteries were ligatured and then cut bilaterally. To evaluation of passive avoidance memory, step-down latency (STL) was measured and LTP was recorded from hippocampal dentate gyrus (DG) after high frequency stimulation (HFS) in all rats. RESULTS: We found that memory was significantly impaired in rats after CHI (P<0.001) concomitant with hippocampal LTP inhibition (P<0.05, P<0.01 for LTP1 and LTP48 respectively). GSE treatment significantly improved memory impairment and increased hippocampal LTP in rats with 2CCAO. CONCLUSION: Our results in present study suggest that GSE exhibits therapeutic potential for short-and long-term memories as well as LTP in DG, which is most likely related at least in part to its antioxidative and free radical scavenging actions.

Effects of fresh, aged and cooked garlic extracts on short- and long-term memory in diabetic rats.

OBJECTIVE: The present study was hypothesized to investigate the beneficial effects of fresh, aged, and cooked garlic extracts on blood glucose and memory of diabetic rats induced by streptozocine (STZ). MATERIAL AND METHODS: Diabetes was induced by an intraperitoneal injection of STZ (60 mg/kg body weight). An oral dose of 1000 mg/kg of each garlic extract was given daily for 4 weeks after diabetes induction. Five days after STZ injection, five groups were formed: Control (intact) rats (Cont) + Vehicle of garlic extract (normal saline) (Veh), STZ + Veh, STZ + Fresh (row) garlic (FG), STZ + Aged garlic (AG), and STZ + cooked (boiled) garlic (CG). In order to assess the passive avoidance memory, rats were gently placed on the wooden platform, and latency to step-down (SDL) was recorded as initial phase, after then a light electrical shock [0.3 mA, 3 sec, Alternative current (AC)] was delivered to their foot paw. The retrieval tests were done for short- and long-term memories, respectively. Blood glucose was assayed by glucometer before and after treatment with STZ and garlic extracts. RESULTS: Hyperglycemia induced by STZ decreased short-term memory in both diabetic males and females rats significantly compared with the controls (p<0.001 and p<0.01). Fresh and cooked but not aged garlic extracts decreased blood glucose in diabetic males and increased memory in both diabetic male and female rats significantly (p<0.05 and p<0.01). CONCLUSIONS: STZ causes elevation of the blood glucose and resulted in memory deficits, possibly viafree radicals production in brain tissue. Garlic has some bioactive chemicals including allicin and sulfur compound (OSC) which could lower the blood glucose during chronic hyperglycemia, inhibit free radicals production in brain, and improve short-term (but not long-term) memory.

Motor disorders and impaired electrical power of pallidal EEG improved by gallic acid in animal model of Parkinson's disease.

The aim of this study was evaluation the effect of Gallic acid on movement disorders and pallidal electrical power in animal model of Parkinson's Disease (PD). PD is clinically characterized by development of motor disturbances, such as bradykinesia, resting tremors, rigidity and a later loss ofpostural reflexes. Oxidative stress is a hallmark factor where the oxidation of dopamine generates Reactive Oxygen Species (ROS) and an unbalanced production ROS induces neuronal damage, therefor leading the neuronal death. Gallic Acid (GA) and its derivatives are present in the plant kingdom and acts as a potent antioxidant. Wistar male rats divided into seven groups randomly with 8 in each. Animals in all groups except control received 8 microg/2 microL 6-hydroxydopamine dissolved in normal saline contains 0.01% ascorbate or vehicle in right Medial Forbrain Bundle (MFB) and a bipolar wire electrode was implanted in the left globus pallidus nucleus of all animals under stereotaxic surgery. Two weeks later PD was approved by contralateral rotation signs induced by apomorphine and then movements and electrical power of pallidal were evaluated. Motor functions and pallidal electrical power were impaired and GA could improve motor dysfunctions and gamma wave power in parkinsonian rats' significantly with higher dose of GA (200 mg kg(-1)). Present result showed that GA may act as a potent antioxidant and free radical scavenger to reverse motor disorders and pallidal gamma wave power after 6-OHDA neurotoxicity in brain.

Crocin attenuates cisplatin-induced renal oxidative stress in rats.

Reactive oxygen species (ROS) and oxidative damage are the most important factors in cisplatin-induced acute renal failure. This study examined the protective effects of crocin against cisplatin-induced renal oxidative stress in rat. Animals were divided into five groups (n=6). Group 1 received normal saline (2 ml/day, i.p.). Group 2 received a single dose of cisplatin (5mg/kg, i.p.). Groups 3-5 received crocin (100, 200, and 400mg/kg, i.p., respectively) for four consecutive days beginning 1-h before a single dose of cisplatin (5mg/kg) on day 1. On day 5, blood samples were drawn and kidneys were removed for histopathological, biochemical and RT-PCR examinations. Twenty four hours urinary chemistries were measured. Blood urea and creatinine and urinary glucose and protein concentrations in crocin-treated groups were significantly lower compared to the cisplatin-treated group. Histopathological studies showed massive damage in the S(3) segment of proximal tubules in cisplatin-treated group but not in crocin-treated groups. Crocin treatment resulted in a significant reduction in malondialdehyde (MDA) concentration and produced a significant elevation in total thiol and glutathione peroxidase concentrations. There was a significant elevation in the mRNA expression of glutathione peroxidase in crocin-treated groups. The results suggest that crocin attenuates cisplatin-induced renal oxidative stress in rats.

Design, synthesis and pharmacological evaluation of 6-hydroxy-4-methylquinolin-2(1H)-one derivatives as inotropic agents.

Selective PDE3 inhibitors improve cardiac contractility and may be used in congestive heart failure. However, their proarrhythmic potential is the most important side effect. In this research we designed, synthesized and evaluated the potential cardiotonic activity of thirteen PDE3 inhibitors (4-[(4-methyl-2-oxo-1,2-dihydro-6-quinolinyl)oxy]butanamide analogs) using the spontaneously beating atria model. The design strategy was based on the structure of cilostamide, a selective PDE3 inhibitor. In each experiment, atrium of reserpine-treated rat was isolated and the contractile and chronotropic effects of a synthetic compounds were assessed. All experiments were carried out in comparison with IBMX, amrinone and cilostamide as standard compounds. The results showed that, among the new compounds, the best pharmacological profile was obtained with the compound 6-[4-(4-methylpiperazine-1-yl)-4-oxobutoxy]-4-methylquinolin-2(1H)-one, 4j, which displayed selectivity for increasing the force of contraction (165 +/- 4% change over the control) rather than the frequency rate (115 +/- 7% change over the control) at 100 microM and potent inhibitory activity of PDE3 with IC(50) = 0.20 microM.

Inotropic and chronotropic effects of 6-hydroxy-4-methylquinolin-2(1H)-one derivatives in isolated rat atria.

BACKGROUND: Selective phosphodiesterase (PDE3) inhibitors improve cardiac contractility and may use in congestive heart failure. However, their proarrhythmic potential is the most important side effect. METHODS: In this research, we evaluated the potential cardiotonic activity of six new synthesized selective PDE3 inhibitors (6-hydroxy-4-methylquinolin-2(1H)-one derivatives) using the spontaneously beating atria model. In each experiment, atrium of reserpine-treated rat was isolated and the contractile and chronotropic effects of a synthesized compound were assessed. The 3-isobutyl-1-methylxanthine, a non-selective PDE inhibitor, was used for comparison. RESULTS: The results showed that, among new compounds, the best pharmacological profile was obtained with the compound 6-[4-(4-methylpiperazine-1-yl)-4-oxobutoxy]-4-methylquinolin-2(1H)-one, C6, which displayed selectivity for increasing the force of contraction (168 +/- 5% change over the control) rather than the frequency rate (138 +/- 5% change over the control) at 300 microM. However, C6 at concentrations of 10 and 100 microM produced left and upward shift in the positive inotropic concentration-response curve of isoprenaline. The -log EC50 of isoprenaline was 8.843 +/- 0.171 in the absence, 9.448 +/- 0.138 and 9.456 +/- 0.107 in the presence of 10, 100 microM of C6, respectively (P<0.001, n = 6). Also, amrinone, a selective PDE3 inhibitor, shifted the isoprenaline concentration-response curve to the left and upward. The concentration of 10 and 100 microM amrinone decreased -log EC50 of isoprenaline to 9.527 +/- 0.287 and 9.423 +/- 0.243, respectively (P<0.001, n = 6). Moreover, the positive chronotropic effect of isoprenaline was not affected by amrinone or C6. CONCLUSION: This study provides functional evidence for the positive inotropic effect of C6. Considering the augmentation of isoprenaline positive inotropic concentration-response with C6 and amrinone, we conclude that C6 produces its effect via potentiation of cAMP-dependent signaling system and possibly by inhibition of PDE3 activity.