Mnemonic and histopathological assessment of the neuroprotective effects of Murraya koenigii leaves extract in rats with partial global cerebral ischaemia

Preclinical studies have reported that Murraya koenigii leaves (MKL) could enhance memory. MKL is also known for its antioxidant activity. The current study was to assess the possible neuroprotective potential of MKL methanolic extract in a two vessel occlusion (2VO) rat model of partial global cerebral ischaemia. Methods: Rats were divided into memory and learning groups. Each group was subdivided into sham control, untreated 2VO and MKL-treated 2VO subgroups. The Morris water maze test was implemented to assess the rats’ cognitive function postoperatively. Brain samples were histopathologically examined for viable neurons within the CA1 hippocampal region. Results: Water maze test findings showed that MKL positively improved memory and learning impairments. However, this improvement in memory test for the treated group was still significantly inferior to that of the healthy control group. Additionally, MKL treated group exhibited insignificant difference in the number of viable hippocampal CA1 pyramidal neurons from that of the untreated 2VO group, whereas both MKL treated and untreated 2VO groups showed significantly less viable neurons when compared with the control group. Conclusion: MKL extract modestly improved memory without providing substantial neuroprotective action to the hippocampal neurons in rats with chronic partial global cerebral ischaemia

HYPOTENSIVE ACTIVITY OF THYMOQUINONE IN NORMOTENSIVE RATS AND ITS RECEPTOR MECHANISMS

Objective: The objectives of the current study were to confirm the blood pressure lowering effect of thymoquinone (TQ) and to investigate its mechanism through muscarinic and β-adrenergic receptors.Methods: Mean arterial blood pressure (MAP) was recorded using the non-invasive blood pressure tail-cuff technique. A dose-response relationship was obtained after using 3 TQ doses (2.5, 5 and 10 mg/kg) intraperitoneally to 3 different groups (n =5) of adult rats under pentobarbital anesthesia. MAP was then measured for another 2 animal groups pretreated either with atropine (P-at) or propranolol (P-pro) followed by 10 mg/kg TQ.Results: TQ produced a significant dose-dependent blood pressure and heart rate lowering effect. TQ-induced MAP reduction was significantly less pronounced in P-at (12±2.8 mmHg) than non-pretreated group (29±3.2 mmHg) with P<0.01. Conversely, TQ-induced MAP reduction in P-pro (28±3.4 mmHg) did not demonstrate a significant difference from the non-pretreated group (29±3.2 mmHg) with P>0.05.Conclusion: This study confirms the dose-related hypotensive effect of TQ and provides an evidence for the traditional use of Nigella sativa for the treatment of hypertension. The mechanism of TQ-induced hypotension involves at least in part activation of vascular muscarinic receptors, but not β-adrenergic receptors

Chronic LD50 vs safest dose for the methanolic extract of curry leaves (Murraya koenigii) cultivated in Malaysia

Curry leaf viz. Murraya koenigiil eaves (MKL) is an ancient Ayurvedic medicinal plant that has recently been described as possessing robust anti-inflammatory and antioxidant activities. The current study was conducted to determine the long-term LD50 of the methanolic extract of MKL during daily oral administration. Five groups of Sprague Dawley rats were recruited into the study. Each group comprised of six rats including the control group (1). The oral MKL doses used for groups (2) to (5) were 50, 100, 200 and 400 mg/kg/day, respectively for a duration of ten weeks. The daily measured toxicity parameters were food and water consumption, body weight, general activity in forced swimming test and the cumulative mortalities. Group (5) showed 100% mortality within the first month of the study. Group (4) showed 50% mortality with signs of toxicity for the other 3 animals. Group (3) showed no mortalities but signs of toxicity for one animal were observed. No mortalities or toxicity signs were observed for any of group (2) animals. It can be concluded that the chronic LD50 for Malaysian cultivated MKL is 200 mg/kg/day, and the safest dose of MKL methanolic extract that can be implemented for long-term studies should not exceed 50 mg/kg/day

Receptor mechanisms of thymoquinone-induced hypotension in normotensive rats

Nigella sativa (NS), more commonly known as ‘’Habbattu Sauda’’, is a plant that is traditionally used to control hypertension. Evidence based studies revealed that NS exerts diuretic and blood pressure lowering effect in spontaneously hypertensive rat. While the volatile oil of NS acts centrally by indirect and direct mechanisms to induce cardio-depressant effect in urethane-anaesthetized rats, Thymoquinone (TQ) represents the main active constituent in the volatile oil, which could be the principal substance of the direct mechanism. Objective was to evaluate the hypotensive effect of TQ and its dose-response relationship in normotensive adult rats using the non-invasive tail-cuff technique. To investigate TQ mechanism of action through muscarinic and β adrenergic receptors. Three doses of TQ (2.5, 5 and 10 mg\kg) were used for assessing TQ hypotensive effect in 3 groups of rats (n=5) under sodium pentobarbital anesthesia. TQ was administered intraperitoneally, and mean arterial blood pressure (MAP) was obtained from recording systolic and diastolic pressure readings using the non-invasive tail-cuff technique and the dose-response relationship was obtained. MAP was then measured for other 2 animal groups pretreated either with atropine (P-at) or propranolol (P-pro) followed by 10 mg/kg TQ. This study confirms the dose-related hypotensive effect of TQ. The study showed that the mechanism of TQ-induced hypotension involves at least stimulation of vascular muscarinic receptors, but not β-adrenergic receptors. This study provides an evidence for the traditional use of Nigella sativa for treatment of hypertension

Antihypertensive and antihyperlipidemic activities of thymoquinone in l-name hypertensive rats

Objective: of this study was to evaluate the antihypertensive potential of Thymoquinone TQ and to investigate the underlying mechanism of action. Method: Hypertension was induced in in Sprague Dawley rats (n = 40) by administration of L-Nitro-Arginine Methyl Ester (L-NAME) in drinking water for 4 weeks. At the end of induction period, rats were divided into 6 groups (n = 8); TQ2.5+L-NAME, TQ5+L-NAME, TQ10+L-NAME, captopril+L-NAME, L-NAME only and control. Mean arterial pressure (MAP) and hear rate (HR) were recorded by the non-invasive tail cuff technique weekly for 28 days. Then animals were sacrificed and blood was collected for determination of ACE activity and aldosterone concentration using ELISA. Lipid profile (total cholesterol, LDL, HDL, TRG) was assayed twice; at the end of induction period and at the end of treatment period. Results: TQ reversed the established hypertension in TQ5 and TQ10 groups, and prevented further increase in MAP in TQ2.5 group. Unlike captopril treated group, TQ antihypertensive activity was associated with an increase in serum aldosterone concentration and ACE activity. TQ treatment at the high dose significantly lowered total cholesterol and LDL levels in comparison with the healthy control group at the end of the 4th week of treatment. Conclusion: This study confirms the antihypertensive effect of TQ which did not take place through inhibition of ACE, but probably through blocking angiotensin II receptors

Protective effect of treatment with black cumin oil on spatial cognitive functions of rats that suffered global cerebrovascular hypoperfusion

The fixed oil of black cumin seeds, Nigella sativa L. (NSO), has shown considerable antioxidant and anti-inflammatory activities. Chronic cerebral hypoperfusion has been linked to neurodegenerative disorders including Alzheimer’s disease (AD)and its subsequent cognitive impairment in which oxidative stress and neuroinflammation are the principal culprits. Cerebrovascular hypoperfusion was experimentally achieved by bilateral common carotid arteries occlusion (2VO) in rats. Morris water maze (MWM) test was employed to assess the effects of NSO on spatial cognitive function before and after 2VO intervention. Rats were divided into long-term memory (LTM) and short-term memory (STM) groups, each was further subdivided into 3 subgroups: sham control, untreated 2VO and NSO treated 2VO group. All subgroups were tested with MWM at the tenth postoperative week. Working memory test results for both sham control and NSO treated groups showed significantly lower escape latency time and total distance travelled than untreated 2VO group. Similarly, LTM and STM MWM tests for sham control and NSO treated groups revealed significantly better maze test performance as compared to untreated 2VO group. Sham control and NSO treated 2VO groups demonstrated superior probe memory test performance as compared to untreated 2VO group. The fixed oil of Nigella sativa seeds has demonstrated noticeable spatial cognitive preservation in rats challenged with chronic cerebral hypoperfusion which indicates a promising prospective neuroprotective effect

Assessment of reactive oxygen species status and neuroprotection by Vitamin E in chronic cerebral hypoperfusion induced neurodegeneration in rats

Background Chronic cerebral hypoperfusion has been linked with cognitive decline in aging and Alzheimer's disease (AD). A reduced cerebral blood flow (CBF) is considered to be a predictive marker for the progression into Alzheimer's disease. In order to tackle the neuropathological consequences of such a reduction in CBF a similar condition was created in experimental animals. Chronic cerebral hypoperfusion induced neurodegeneration was produced by common carotid artery occlusion (2 vessel occlusion, 2VO) in rats. Since oxidative stress, leading to neuronal apoptosis and death, is one of the mechanisms which is thought to play a significant role in chronic degenerative neurological disorders, the present study was designed to assess the neuroprotective role of Vitamin E in chronic cerebral hypoperfusion-induced neurodegeneration. Method After acclimatization, thirty Sprague Dawley rats weighing 200-250 g were equally divided into three groups. Group A – sham control, Group B – 2VO, and Group C – 2VO-E (treated daily with Vitamin E, 100 mg/kg, orally following 2VO). On the 8th week, all the rats were euthanized and the hippocampi were isolated. Viable neuronal cell count in the hippocampal CA-1 region was estimated. Results There was significant difference in neuronal cell death in 2VO group as compared to sham control group. In Vitamin E-treated 2VO (2VO-E) rats, the viable neuronal cell count of the hippocampal CA-1 region was significantly higher as compared to the untreated 2VO group. Conclusion Vitamin E is an effective neuroprotective agent in chronic cerebral hypoperfusion-induced neurodegeneration in rats and can be effectively utilized in the management of AD. The antioxidant activity of Vitamin E is in progress and will be evaluated by the measurement of Isoprostane F2 through Enzyme-Linked Immunosorbent Assay

Effect of Nigella sativa on chronic cerebral hypoperfusion-induced memory and learning impairment

Memory and learning impairment in elderly is becoming an increasing challenge especially in those with vascular risk factors. The fixed oil of Nigella Sativa NSO (black cumin) has revealed considerable antioxidant, anti-inflammatory and immune-modulatory effects which may prevent or arrest the deteriorating learning and memory brain function. Two vessel occlusion (2VO) in rats has been broadly used as a model for chronic cerebral hypoperfusion. The present experimental study was planned to use Morris water maze (MWM) test to compare the cognitive performance of rats with memory and learning deficits induced by 2VO surgery with that of a healthy Sham control animal group and orally treated with the NSO. 60 Sprague Dawley (SD) rats were equally divided into 2 main groups for long term memory (LTM) protocol and short term memory (STM) with (working memory) protocol of MWM. Each group was subdivided into 3 subgroups (n=10) – Group A, untreated 2VO; Group B, sham control and Group C, orally NSO treated 2VO. For LTM and STM Morris water maze test, both Sham control and NSO treated groups showed significantly lower escape latency time (p<0.01), total distance travelled (p<0.01), longer time spent in the target zone and a higher number of annulus crossings as compared to untreated 2VO group. Working Memory MWM test for both Sham control and NSO treated groups showed significantly lower escape latency time (p<0.01) and total distance travelled (p<0.01) as compared to untreated 2VO. The study suggests that the seeds of Nigella sativa may have potential memory and learning enhancing activity and may open the way for prophylactic use to patients with early signs of memory and/or learning deficits or even those who are at high risk for developing neurodegenerative diseases like Alzheimer’s disease

The effect of flaxseed ethanolic extract on the structure of the kidney and the endocrine pancreas in streptozotocin induced diabetic rats

Background: The present investigation has been designed to study the possible protective effect of flaxseed extract on the structures of the endocrine pancreas and kidneys of streptozotocin (STZ) induced diabetic rats for 30 days. Methods: Forty male Sprague-Dawley rats were randomized into five groups (n=8). Normal control group (NC); received distilled water orally, normal flaxseed group (NF); treated orally with (400 mg/kg) extract of flaxseed, diabetic control group (DC); treated with single intraperitoneal dose of STZ (60 mg/kg), diabetic flaxseed group (DF); diabetic rats treated with extract of flaxseed (400 mg/kg), diabetic glibenclamide group (DG); diabetic rats treated with (0.6 mg/kg) glibenclamide. Results: Histological observation of sections in pancreas in DC group revealed shrunken islets of Langerhans with degenerated and degranulated β-cells, vacuolations and congested capillaries while sections of kidneys showed shrinkage of some glomeruli and degeneration of others with wide urinary space and hydropic degeneration in some tubular epithelial cells, dilated tubules and cell debris scattered in tubular lumina. These pathological changes were ameliorated in the flaxseed extract and glibenclamide treated rats. Conclusions: It is concluded that flaxseed extract may represent a good alternative treatment for management of diabetes and its related complications such as diabetic nephropathy

Neuroprotective effect of black cumin oil against cerebrovascular hypoperfusion induced pyramidal cell loss in rats

Critically attained threshold cerebrovascular hypoperfusion (CATCH) hypothesis is believed to cause age related neurodegeneration. Such threshold was successfully achieved in rats by permanent bilateral common carotid artery ligation (PBCCAL) and the earliest neurons to undergo neurodegeneration were found to be the pyramidal cells of hippocampal CA1 region. Nigella sativa oil extract (NSO) was found to preserve viability of cell in cerebellar neurons culture in vitro putting forward its potential neuroprotective effect. Therefore, the current study was conducted to perform a quantitative histopathological assessment of neuroprotective effect of NSO on CA1 hippocampal pyramidal cells on rats with CATCH induced by PBCCAL. 30 rats were equally divided into three groups: sham control (operated without PBCCAL and no treatment received), untreated PBCCAL (operated with PBCCAL only) and NSO treated group (operated with PBCCAL and received daily oral NSO treatment). After the 10th postoperative week coronal sections of the dorsal hippocampus were stained with cresyl violet stain. The number of viable pyramidal neurons in 1mm horizontal distance of CA1 area on high power field (HPF)magnification power was calculated in all sections. Viable pyramidal neurons on HPF Light Microscopy appeared normal with well demarcated cell membrane and a distinct nucleus, while non-viable cells appeared shrunken with irregular outline and dark pyknotic nucleus. The average number of viable pyramidal cells within CA1 hippocampal region was significantly higher in sham control and NSO treated groups as compared to the untreated PBCCAL group (p<0.01). Furthermore, the difference was not significant when comparing the number of viable pyramidal cells for sham control and NSO treated groups (p>0.05). It can be concluded that NSO has the potential to protect hippocampal pyramidal cells from neurodegeneration induced by PBCCAL. This fact represent the doorway to use NSO to prevent age related neurodegeneration namely Alzheimer’s disease and its subsequent cognitive impairment